Photovoltaics glossary
In the large Photovoltaics glossary for commercial photovoltaic systems, you will find all important and significant technical terms and abbreviations simply explained. Stay up to date with the solar lexicon from CUBE CONCEPTS. From "A" for acceptance guarantee to "Z" for bidirectional meter.
CUBE CONCEPTS will be happy to answer any further questions you may have about commercial photovoltaic systems.
The big photovoltaic glossary from A to Z
A
The so-called 7,000-hour rule grants large electricity consumers in Germany that consume at least 10 GWh at 7,000 full-load hours per year discounts of up to 90 % on grid fees. The main beneficiaries are around 580 companies from industry, which will save a total of 1.5 billion euros in 2024. The reductions start at 80 % and increase in stages. This regulation has been criticized as it restricts flexibility in electricity consumption and makes it more difficult to use green surplus electricity.
More about the 7,000-hour rule
An electricity purchase guarantee is a contract between an electricity producer and an electricity consumer that regulates the conditions for the supply and purchase of electricity. Essentially, the electricity consumer undertakes to purchase a certain amount of electricity at an agreed price, while the electricity producer undertakes to supply this amount of electricity.
An electricity purchase guarantee is generally advantageous for the electricity producer, as it gives them a certain degree of planning security and enables them to obtain financing for their systems. At the same time, it can also be advantageous for the electricity consumer, as they can secure the price of electricity over a longer period of time and are thus protected from short-term price fluctuations on the electricity market.
In some countries, there are special support programs that provide for the conclusion of electricity purchase guarantees for electricity from renewable energies. These programs are intended to promote the expansion of renewable energies and provide electricity producers with better planning security.
It is important that all terms and conditions of the power purchase guarantee are carefully reviewed to ensure that they are fair to both parties and that the delivery and purchase of the electricity goes smoothly. Important aspects that should be regulated in an electricity supply guarantee include the duration of the contract, the quantity and price of the electricity, the delivery conditions, the payment conditions and the conditions for terminating the contract.
The shading of solar cells is an important factor that can influence the performance and efficiency of solar power systems. If a solar cell is partially or completely covered by shade, this can lead to a reduction or even complete failure of the cell's performance.
This is because solar cells are designed to absorb sunlight and convert it into electrical energy. However, if part of the solar cell is covered by shade, this part of the cell array cannot absorb enough light to generate the same amount of energy as the uncovered part of the cell. This can result in the current flow in the cell being disrupted and the entire system becoming inefficient.
It is important to note that shading can be caused not only by buildings or trees, but also by other solar cells in the system itself. If one solar cell is shaded, this can have an impact on the entire system, as solar cells are connected in series and a shaded cell can reduce the current flow in the entire chain.
Special technologies can be used to minimize the effects of shading on solar cells. For example, so-called bypass diodes can be used to divert the current flow around the shaded cell and thus minimize energy loss. In addition, intelligent control systems can be used to automatically find the optimum operating point for the system and thus minimize energy loss due to shading.
Overall, the shading of solar cells is an important factor that should be taken into account when planning and installing solar power systems. However, the use of suitable technologies and controls can ensure the efficient use of solar energy even in shaded environments.
AC or alternating current is a type of electric current in which the direction and strength of the current changes periodically. In contrast, the current in direct current (DC) flows constantly in the same direction.
AC is normally used in electrical grids and appliances as it is more efficient and cost effective to transmit electrical energy over long distances. This is because the current can be transformed by transformer and induction coils to increase or decrease the voltage, which reduces resistance and energy loss.
The frequency of the AC current varies from country to country, but it is usually either 50 or 60 Hertz (Hz).
The AC rated power is the maximum power that an electrical device or electrical system can deliver under normal operating conditions with alternating current. It is also referred to as rated power or rated current.
The rated AC power depends on various factors, such as the voltage and frequency of the alternating current, the efficiency of the appliance or system, the temperature and the environment. It is normally specified in watts (W) or kilowatts (kW).
It is important to know the power rating of an appliance or system to ensure that it is compatible with the power supply and will not be overloaded. If an appliance or system is overloaded, it can cause damage or failure and even pose a fire risk.
Amortization refers to the process of gradually reducing or paying off debt or investments over a period of time. In general, amortization is used to describe the repayment of debt or the depreciation of assets. Today, the amortization period for photovoltaic systems is around 7-8 years.
For debt, amortization means that a borrower makes regular payments to repay the borrowed amount and interest until the debt is fully repaid. The regular payments consist of a portion of interest and a portion of principal repayments, with the principal portion gradually increasing with each payment, while the interest portion decreases.
For investments or assets, amortization means that their costs are spread over a period of time and depreciated gradually. This is usually applied to assets such as buildings, machinery or software in order to spread their costs over their useful life and more accurately reflect the company's profit and book value.
Ampere is the unit for the electrical current in an electrical circuit. It is named after the French physicist André-Marie Ampère, who made a significant contribution to the development of the electromagnetic field concept.
An ampere is defined as the strength of a constant current that generates a force of 2 × 10^-7 newtons per meter of conductor length when flowing through two parallel, infinitely long and thin-walled conductors in a vacuum at a distance of one meter from each other.
The unit is represented by the symbol "A" and is one of the seven base units of the International System of Units (SI). Electrical currents are usually measured using a measuring device called an ammeter.
The system operator of a solar energy system is the person, company or organization that owns, operates and is responsible for the generation of solar energy. The system operator can be a private homeowner who has installed a small solar system on their roof or a company that operates a large solar system on a ground-mounted or building roof.
As the system operator, you are responsible for the proper installation, maintenance and repair of the solar system. It is also the system operator's responsibility to ensure that the system complies with the applicable legal requirements and has received all necessary permits and registrations. Furthermore, the system operator is responsible for the sale or use of the solar energy generated.
Every photovoltaic system is as individual as your company and must therefore be planned anew for every project. At CUBE CONCETPS, this is done in nine steps:
- Analysis meeting
- Indicative offer, planning & design
- Mandating
- Detailed measurement for the bill of quantities
- Invitation to tender
- Contract award
- Construction / Installation
- Operational management
- Monitoring
A Plant certificate for a PV system is a document that confirms that the system meets the technical and regulatory requirements for connection to the grid. It is particularly necessary for larger systems that are connected to the medium or high-voltage grid. It ensures that the system complies with the applicable grid connection guidelines, such as the VDE-AR-N 4110/4120 in Germany. It also proves that the PV system fulfills important functions such as reactive power control and behavior in the event of grid faults (fault ride-through). The certificate, which is issued by an accredited test center, also includes the testing of central components such as inverters and protective relays to ensure grid stability.
The anti-reflective layer is a coating on the surface of solar modules that serves to reduce the degree of reflection of light. This enables greater light transmission and therefore greater efficiency in the conversion of sunlight into electricity.
When light hits the surface of a solar module, some of the light may be reflected instead of absorbed. This can lead to a loss of energy and efficiency. The anti-reflective layer reduces the degree of reflection by increasing the refraction of the light, which means that more light can penetrate the module.
The anti-reflective coating is usually made from a thin layer of materials such as silicon dioxide or titanium dioxide. It is an important component of solar modules to ensure that they can absorb as much solar energy as possible and convert it into electricity.
The Atypical grid usage describes a special type of electricity use in which companies manage their energy consumption in such a way that they avoid peak load times in the electricity grid. By shifting their electricity consumption to times with lower grid loads, these companies benefit from significantly reduced grid charges. This measure helps to increase grid stability and reduce grid expansion costs by achieving a more even utilization of the electricity grid. Prerequisites include ensuring that the maximum load during defined peak load time windows is sufficiently far away from the absolute annual maximum load and that there is a minimum shift potential of 100 kW.
Rooftop systems are PV systems on large commercial and industrial roofs. Large commercial and industrial roofs in particular are ideal for generating electricity cheaply and ecologically using solar systems, as they are usually unshaded and the energy produced is consumed directly on site. Photovoltaics on roof surfaces produce green and cheap electricity on a permanent basis and significantly reduce a company's electricity costs. In addition, they reduce the carbon footprint, ensure constant electricity prices for a company in the long term and increase the value of the property.
Rooftop mounting is a type of solar system installation in which the solar panels are attached to a roof. The solar modules are attached to roof beams or supports, which in turn are mounted on the roof surface.
Rooftop mounting is one of the most common installation methods for photovoltaic systems. It offers several advantages, including
Space-saving: Solar panels are installed on the existing roof without requiring additional space.
Inexpensive: Roof-mounted installation is generally cheaper than other types of installation, such as free-standing installation.
Simple installation: Installing solar modules on a roof is generally easier and quicker than other types of installation.
Low impact on the environment: As the solar panels are installed on the roof, they have no negative impact on the environment or landscape.
However, rooftop mounting is not always the best option. It depends on various factors, such as the type of roof, the roof pitch, the load capacity of the roof, the orientation of the roof to the sun and other local conditions. It is important that careful planning and calculation is carried out to determine the optimum mounting method for each specific situation.
An elevation is a mounting structure that is used to set up solar panels and align them at an angle to the sun. It is a metal or aluminum structure on which the solar panels are mounted and which is then fixed to a foundation or roof.
Elevation enables the solar modules to be optimally aligned with the sun in order to achieve maximum solar energy yield. The alignment depends on various factors, such as the width and length of the site, the geographical location and the inclination of the terrain.
An elevation can be either single-axis or dual-axis adjustable. With a single-axis adjustable mounting, the inclination of the solar module can be changed to adapt it to the position of the sun. A two-axis adjustable mounting also offers the option of adjusting the azimuth direction (i.e. the alignment in relation to the cardinal points) of the solar module.
Elevation is particularly useful if the roof pitch or roof orientation is not optimal for a good solar energy yield. It can also make it easier to clean solar installations in areas with a lot of snow in winter.
Azimuth is a term used in astronomy, geodesy and navigation and refers to the orientation of an object in relation to the cardinal points. In general, azimuth refers to the horizontal angle between a particular direction and true north.
In the solar industry, the azimuth is an important parameter for the planning and installation of photovoltaic systems, as it indicates the direction in which the solar panels must be aligned in order to obtain maximum solar radiation. Azimuth is often measured in degrees from 0° to 360°, with 0° corresponding to true north and 180° to true south.
The azimuth angle depends on various factors, such as the geographical location, the time of year and the time of day. To determine the optimum orientation for solar panels, you need to calculate the azimuth for the specific location and time and then adjust the orientation of the solar modules accordingly.
More about the ideal alignment of PV systems in our report.
To achieve self-sufficiency through solar power, you need to install a large enough solar system that produces enough electricity to meet your needs. Here are some steps you can take:
Determine your electricity requirements: Check your average electricity consumption in kilowatt hours (kWh) per day to find out how big your solar system should be. This value is usually indicated on your electricity bill.
Determine your location: The amount of electricity your solar system can produce depends on your location. Make sure you know the number of hours of sunshine in your region.
Plan your solar installation: The size and output of your solar installation will depend on your electricity requirements and your location. A solar installer can help you plan a system that is suitable for your needs.
Apply for the necessary permits: Depending on the location and size of your solar installation, you may need planning permission or other permits from the local authorities.
Install your solar system: Once you have received the permits, your solar system can be installed. A professional solar installer can help you with this process.
Connect your system to the grid or install an electricity storage unit: If you do not want to feed the surplus electricity into the grid, you can also install an electricity storage unit to store the electricity produced and use it later.
With a well-planned and installed solar system, you can cover your electricity needs by using renewable energy and thus become self-sufficient. However, please note that the cost of such a system can vary depending on its size and location, and it may also require further investment in the energy efficiency of your property.
E
The EEG is the German Renewable Energy Sources Act, which came into force in 2000 and has been continuously developed since then. It is the central control instrument for the expansion of renewable energies. The aim of the EEG is to restructure the energy supply and increase the share of renewable energies in the electricity supply to at least 80 percent by 2050. The expansion of renewable energies is particularly in the interests of climate and environmental protection to develop a sustainable energy supply. It currently envisages that Germany will become climate-neutral by 2045 and that 80% of its total electricity requirements will come from renewable energies by 2030. Funding programs and other measures are enacted as part of the EEG.
EEG commissioning refers to the time after a photovoltaic system generates electricity for the first time. This has been defined by the EEG clearing office, as various deadlines for the operator of a PV system depend on this point in time. For example, the amount of the feed-in tariff also depends on this.
With the introduction of the EEG in 2000, the EEG levy, also known as the "green electricity levy", was also implemented. Among other things, it serves to finance the expansion of solar and wind power plants. It was charged to end customers via the electricity bill until 01.07.2022 and amounted to 3.72 cents per kilowatt hour at the time.
Self-consumption is the proportion of solar power that the operator of a photovoltaic system can consume themselves. The higher this is, the better or more economical a PV system is. Surplus solar power, which can be generated by a commercial PV system at weekends, for example, is usually fed into the public grid and the producer then receives a feed-in tariff.
The self-consumption rate is the percentage of solar power that an operator of a commercial photovoltaic system consumes themselves. If a PV system generates more electricity than the company needs, the surplus solar power can be fed into the public grid and the producer receives a feed-in tariff. If a company consumes more electricity than its own PV system with electricity storage can supply, it must purchase electricity from the public grid.
Feed-in management (also known as "grid management") is a method used by energy supply companies and grid operators to control the flow of electricity into the public electricity grid. Feed-in management becomes necessary when more electricity is generated from renewable energy sources than the electricity grid can absorb and transport.
Feed-in management is intended to prevent the electricity grid from being overloaded, which can lead to power outages. There are various methods of feed-in management, for example, electricity generators can be temporarily throttled to reduce electricity production and thus ensure grid stability.
In Germany, feed-in management is regulated by law under the Renewable Energy Sources Act (EEG). Grid operators are obliged to use feed-in management in the event of an impending grid bottleneck and to inform the affected electricity producers.
A feed-in point is a location where electrical energy is fed into the electricity grid by an electricity generator or a feeder. A typical example of a feed-in point is a solar power plant that feeds the electricity generated into the public grid.
A feed-in point can also be a building that has its own electricity generation system, such as a photovoltaic system or a combined heat and power plant, and feeds surplus electricity into the grid. As a rule, the feed-in takes place via a so-called grid connection point (also known as a feed-in point), at which the electricity grid is connected to the feeder.
Operators of feed-in points are generally obliged to register their systems with the responsible grid operators and to meet certain technical requirements in order to ensure a safe and reliable feed-in to the electricity grid.
The feed-in tariff is a state-guaranteed payment that operators of systems for generating electricity from renewable energy sources (such as solar, wind, hydropower or biomass systems) receive for the electricity fed into the electricity grid. The amount of the feed-in tariff is usually guaranteed for a certain period of time and can vary depending on the type and size of the system, the amount of electricity generated and the time of commissioning.
The feed-in tariff is intended to offer the operators of renewable energy systems planning security and create an incentive to invest in renewable energies. In many countries, including Germany, the feed-in tariff has been used as an instrument to promote renewable energies and has helped to accelerate the expansion of renewable energies.
However, feed-in tariffs have changed in some countries over time, for example through reductions or the introduction of tendering procedures. In some cases, the feed-in tariff has also been replaced by other instruments to promote renewable energies.
A feed-in meter is an electronic measuring device that records the electricity produced by a power generation system that is fed into the public electricity grid. The feed-in meter therefore measures the amount of electricity produced by the system that is fed into the electricity grid.
A feed-in meter is generally required by the operators of electricity generation plants in order to calculate the feed-in tariff for the electricity fed in and to ensure that the amount of electricity fed in corresponds to the amount of electricity actually produced.
Depending on the country and region, the requirements for feed-in meters and their installation location may vary. As a rule, feed-in meters are installed and maintained by the grid operators to monitor and ensure the proper feed-in of electricity from renewable energy sources.
The best electricity yield from solar modules is achieved with vertical irradiation from the sun. However, diffuse irradiation also leads to a good yield with modern solar panels. As a general rule, PV modules should ideally face south in order to achieve the highest energy yield. The so-called azimuth angle is 0°. In Germany, an orientation between south-east and south-west at an azimuth angle of 45° or -45° is still considered sensible and the optimum tilt angle is around 30°. However, other solutions also make sense in relation to the roof area and yield. Orientation to the east and west on a flat roof has the advantage that the modules can be installed in any direction.
This means that more modules can be installed on the same surface area.
Charging stations are electric charging stations where electric vehicles can be charged. They are an important part of the infrastructure for electromobility and can be installed in public places such as streets, parking lots, shopping centers or service stations.
Charging stations can have different charging capacities and plug types to serve different types of electric vehicles. There are AC charging stations, which provide alternating current (AC), and DC charging stations, which provide direct current (DC). DC charging stations can usually charge electric vehicles faster than AC charging stations as they offer higher charging capacities.
In some countries, such as Germany, there are government funding programs for the development of charging infrastructure to support electromobility. The number of charging stations is steadily increasing worldwide in order to meet the growing demand for electromobility and ensure a nationwide supply of charging facilities.
The electroluminescence process (EL process for short) is a process for generating light in semiconductor components such as diodes and displays. It is based on the emission of light through electrical excitation of semiconductors.
In the EL process, a voltage is applied to a semiconductor, which raises electrons to higher energy states. When these electrons return to lower energy states, light is emitted in the form of photons. The light emitted depends on the properties of the semiconductor and can be controlled by the choice of materials and the coating on the substrate.
The EL process is used to produce light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs), which are used in lighting, display and display technology. OLEDs have the advantage of being flexible, light and thin and can be used in various applications such as smartphone displays, televisions, lighting and wearables.
Electromobility / e-mobility refers to the movement of people and goods using electronic drives. This includes, for example, e-bikes, e-cars, electric commercial vehicles and trains. In the course of the transport transition, however, this also includes the necessary charging infrastructure. Electric mobility as a whole is an important component of a sustainable and climate-friendly transportation system.
Energy payback is a concept that indicates how long it takes for a renewable energy source to produce enough energy to compensate for the energy used to manufacture, install and maintain the system.
Energy payback is an important factor in assessing the environmental impact of renewable energy technologies. It indicates how long it takes for the energy generated from renewable sources to compensate for the energy required to build and operate the plant.
In order to calculate the energy payback, various factors must be taken into account, such as the energy required to manufacture the system and the required infrastructure, the energy used for installation and maintenance, the expected service life of the system and the amount of energy produced during this time.
Energy payback is an important factor in assessing the sustainability of renewable energy technologies and can help to reduce the environmental impact of using renewable energy sources.
The Energy Efficiency Act aims to reduce energy consumption and improve efficiency. It can provide for measures such as energy audits, binding targets, support programs and reporting in order to achieve this goal.
Find out more in our report on the EnEfG.
The energy payback time (EPT) is the time required to compensate for the energy used to manufacture a particular technology or system.
In the renewable energy sector, energy payback time usually refers to the time it takes to produce the energy used during the manufacture, installation and maintenance of a particular technology. For example, the energy payback time indicates how long it takes for a photovoltaic system to produce enough energy to compensate for the energy required to manufacture the solar modules, mounting systems and inverters.
The energy payback time depends on various factors, such as the type of technology, the type of materials used and the energy source from which the required energy comes. A short energy payback time means that the technology produces energy quickly to compensate for the energy used to produce the equipment, which is an indicator of the sustainability and cost-effectiveness of the technology.
The energy payback time is an important factor in the evaluation of technologies and can help to assess the environmental impact and economic aspects of technologies.
An energy supplier usually refers to the public energy supplier that supplies a company with electricity from the public grid. The four largest energy suppliers in Germany are, for example, RWE AG, EnBW AG, E. ON SE and Vattenfall.
A Energy Management System (EMS) is a digital platform that helps companies to efficiently monitor, control and optimize their energy consumption. How the CUBE EfficiencyUnit an EMS collects energy data in real time, analyzes consumption patterns, identifies potential savings and enables the integration and control of renewable energy sources. With functions such as automated control, load management and reporting, an EMS helps to reduce energy costs, achieve sustainability targets and increase energy efficiency across the entire operation.
EMAS is an environmental management system for companies. In our contribution to EMAS to find out more about this topic.
Renewable energies or regenerative energies are energy sources that are inexhaustible or, unlike fossil fuels, are renewed relatively quickly. They include bioenergy, geothermal energy, hydropower, ocean energy, solar energy and wind energy. They stand for a sustainable energy supply and are fixed components of the energy transition.
The harvest factor provides information on how much electricity a photovoltaic system can produce over its entire service life. It has steadily increased in recent years as solar modules have become more and more effective and durability has increased. PV systems are now expected to have a life cycle of 30 years or more. The harvest factor therefore goes beyond the key figure of energy amortization.
Backup power for solar systems or a backup power supply is when no more electricity flows from the solar system and the local consumers are supplied from an electricity storage system or the public grid. This changeover is automatic and occurs, for example, in the dark, in the event of a fault or if more electricity is required than the PV system can produce.
The Yield of a PV system refers to the amount of electrical energy produced by the system over a certain period of time. The level of yield depends on various factors, such as the size of the system, the number and efficiency of the solar cells, the orientation and inclination of the modules, the intensity and duration of the solar radiation, the air temperature and shading.
The yield of a PV system is usually measured in kilowatt hours (kWh) and can be calculated for different time periods, such as a day, a week, a month or a year. The yield is usually recorded by an inverter and can be monitored in real time by a monitoring system.
The level of yield is an important factor when assessing the economic viability of a PV system. A higher yield means that the system produces more energy and can therefore offset the costs of installing and operating the system more quickly. In addition, a higher yield can help to reduce CO2 emissions and reduce dependence on non-renewable energy sources.
Calculating the yield of a PV system is complex and depends on many factors. A professional solar technician can plan and install the system in such a way that an optimum yield is achieved.
See also "Yield". In the yield forecast, various factors such as system size, orientation, terrain categories or the solar atlas are set in relation to each other and a forecast for the profitability calculation is created. The yield forecast is an important part of planning a photovoltaic system and is prepared by CUBE CONCEPTS before every PV project.
ESG stands for environmental, social and governance and refers to the three main categories of factors considered by companies and investors to assess their sustainability and social impact. These are environmental factors, social aspects and aspects of corporate governance.
Find out more about ESG on our ESG strategy consultings-side.
An overview of certifications, standards and norms can be found in our blog post Sustainability & ESG.
The European efficiency (also referred to as "module efficiency" or "standard efficiency") is a characteristic value for the efficiency of a photovoltaic (PV) system and indicates the ratio between the electrical power produced by the system and the irradiated solar energy.
In contrast to cell efficiency (which indicates the efficiency of an individual solar cell), European efficiency refers to the efficiency of the entire PV module (including all cells and the module electronics).
The European efficiency is usually given as a percentage and typically lies between 15% and 20%, depending on the type and quality of the solar cells used, the design and size of the module and other factors such as temperature and solar radiation.
European efficiency is an important factor when selecting PV modules and calculating the expected output of a PV system. The higher the efficiency, the more energy can be produced by the system, which leads to higher yields and faster amortization of the investment costs.
M - N
The maximum power point (MPP) is the point on the current-voltage curve of a solar cell or photovoltaic system at which the maximum power (in watts) is generated.
The MPP voltage depends on various factors, such as the intensity of the sunlight, the temperature and the condition of the photovoltaic module. In order to obtain the maximum power from a photovoltaic system, it is necessary to control the operation of the system so that it always works close to the maximum power point. This is achieved using special devices known as power optimizers or maximum power point trackers (MPPT).
The Market Master Data Register is a comprehensive official register for the German electricity and gas market, which is managed by the Federal Network Agency. It is abbreviated to MaStR and is used by authorities and market players. The MaStR is primarily used to register master data on electricity and gas generation plants. The master data of plant operators, grid operators and energy suppliers must also be registered there.
Medium-voltage systems are electrical systems that transmit and distribute energy at medium voltage levels. As a rule, the voltage level is between 1 kV and 36 kV. Medium voltage is generally used to supply electricity to urban areas, commercial and industrial facilities and larger public buildings.
Medium-voltage systems consist of various components such as switchgear, transformers, cables and protective devices. The switchgear is the central element of the medium-voltage system and is used to control and protect the power supply. Transformers are used to transform the voltage to a higher or lower level, while cables transport the electrical energy from the switchgear to the consumers. Protective devices such as overcurrent protection relays, overvoltage protection relays and protective relays for earth faults are used to protect the system from faults or damage.
Medium-voltage systems are used by energy supply companies, industrial companies and public institutions. They play an important role in the energy supply of cities and regions and are of great importance for the infrastructure of modern societies.
The frequency and type of cleaning of solar modules depends on various factors, such as the location of the modules, the environment in which they are located, air pollution, precipitation levels and other climatic conditions. In general, however, solar modules do not need to be cleaned often, as rain and wind are sufficient to keep them clean in most cases.
However, if cleaning is required, solar modules should be cleaned carefully and with suitable cleaning agents to avoid damage. As a rule, they can be cleaned with water and a mild detergent, such as washing-up liquid. High-pressure cleaners or abrasive cleaning agents should be avoided as they can damage the surface of the modules.
The cleaning of solar modules should ideally be carried out by a specialist to ensure that the modules are not damaged and that electrical safety is guaranteed. It is recommended to have solar modules cleaned every 1-2 years to maintain their performance. In areas with high levels of dust or dirt, more frequent cleaning may be required.
A module string is a group of solar modules that are connected in series to achieve a higher voltage and output. As a rule, module strings consist of 8 to 20 modules that are connected together. A module string is one of the basic components of a photovoltaic system.
Module efficiency is a measure of how efficiently a solar module converts sunlight into electrical energy. It indicates the ratio of the electrical power generated by the module to the incident radiant power of the sunlight and is expressed as a percentage.
Photovoltaic monitoring refers to the continuous monitoring of a PV system using specially developed software. The cloud-based platform CUBE Vision PHOTOVOLATAIC - MONITORING® specially developed by CUBE CONCEPTS offers many other useful features in addition to cross-company and cross-location monitoring of new and existing photovoltaic systems, making it easier to deal with the entire topic of sustainable energy and power generation.
A monocrystalline solar cell is a solar cell that is made from a single crystal of silicon. The crystal is cut from a block of high-purity silicon and then sawn into thin slices called wafers. These wafers are then processed into solar cells.
Monocrystalline solar cells are characterized by their high efficiency, as they have a higher energy conversion efficiency than other types of solar cells due to their uniform crystalline structure. They also have a characteristic black color and rounded corners, which are created by sawing the silicon block.
Monocrystalline silicon is a high-purity form of silicon that is used in the production of monocrystalline solar cells. It is also known as Czochralski silicon, as it is produced using the Czochralski process.
Depending on the type of system, different mounting systems are used for the solar modules. The mounting systems are used to install the solar modules securely on roofs, open spaces or solar carports and to adjust them precisely. They are usually made of metal and are selected and installed on a project-specific basis.
A maximum power point tracker (MPP tracker) is an electronic circuit used in photovoltaic inverters and solar battery charge controllers. It is designed to extract the maximum power from the solar modules by automatically determining and maintaining the optimum operating point voltage of the solar module.
The MPP Tracker constantly monitors the output voltage of the solar module and adjusts the load impedance so that it always operates at the maximum power point (MPP) of the solar module, i.e. where the solar module generates its maximum power. The MPP Tracker uses algorithms and measurements to determine the optimum operating point voltage of the solar module and adjusts the load impedance accordingly.
Multicrystalline silicon is a frequently used material for the production of solar cells. In contrast to monocrystalline silicon, it consists of several small crystallites that grow together and form a larger crystal structure. This results in lower efficiency compared to monocrystalline silicon, but it is significantly cheaper to produce.
MWh stands for megawatt hour and is a unit for the amount of energy. One megawatt corresponds to an output of one million watts, while one hour is a unit of time. A megawatt hour therefore corresponds to the amount of energy generated when an output of one megawatt is maintained for one hour.
MWh is often used to measure the consumption or production of energy, e.g. the energy production of a solar system, the electricity consumption of households or the total amount of energy produced by a power plant.
MWp stands for megawatt peak and is a unit for the nominal output of photovoltaic modules or systems. The nominal output of a solar module or solar system indicates how much electrical power can be generated under standard test conditions (STC).
The standard test conditions include an irradiation of 1000 W/m², a module temperature of 25 °C and an air mass of 1.5. The unit MWp indicates the maximum output that a module or system can generate under these conditions.
In PV systems, tracking refers to the automatic adjustment of the solar modules according to solar irradiation in order to always ensure maximum electricity yield. Special mounting systems are used for this purpose and a distinction is made between single-axis and dual-axis control. On average, yield advantages of between 30 and 45% can be achieved. Tracking systems are mostly used in solar parks and mean higher investment costs and require more space. They are also prone to faults and entail higher maintenance and repair costs.
The optimum angle of inclination for solar modules in Germany is around 30°. In relation between surface area and
yield, however, other solutions also make sense. Orientation to the east
and west on a flat roof, for example, has the advantage that the modules do not shade themselves at any time of year, meaning that more modules can be installed on the same area. Find out more in our report "Tilt angle for solar modules“.
The rated output of a photovoltaic system (PV system) refers to the maximum output that a solar system can generate under standardized test conditions (STC). These conditions include an irradiance of 1000 W/m², a cell temperature of 25°C and an air mass of 1.5.
The nominal output of a PV system is usually specified in watt peak (Wp) or kilowatt peak (kWp). The rated output is an important parameter for comparing and selecting the output of solar modules and photovoltaic systems. It indicates how much power the solar system can generate under optimum conditions.
However, it is important to note that the actual output of a PV system depends on various factors, such as the intensity and duration of solar radiation, the temperature, the angle and orientation of the modules and other environmental influences. Therefore, the actual output of a PV system may deviate from the rated output in practice.
More about Rated power and Wp for solar modules.
The grid connection point (Grid connection point) for PV systems is the point at which the photovoltaic system is connected to the electricity grid. This connection point is important as it determines how the solar energy generated is fed into the grid and which rules and regulations must be observed.
Most PV systems are grid-connected and feed the solar energy they generate into the public grid. The grid connection point is the location where the PV system's electricity meter is installed and where the flow of electricity into the public grid is monitored and regulated.
The grid operator is a company that is responsible for the operation, maintenance and monitoring of the electricity grid in a specific geographical area. The main task of the grid operator is to ensure that the electricity grid is stable and reliable and that the electricity demand of consumers is covered at all times.
The grid operator is usually an independent company that is licensed by the state or regulatory authorities and complies with the regulations and laws relating to the operation of the electricity grid. In some countries, the grid operator is also referred to as the electricity supply company.
In Germany, a distinction is made between around 900 regional distribution system operators (DSOs) and the four large transmission system operators (TSOs).
A grid feed-in device (also known as a feed-in inverter) is an electrical device used in photovoltaic systems to convert the direct current (DC) generated by the solar modules into alternating current (AC) and feed it into the public grid.
The grid feed-in device has the task of adapting the output of the solar system to the power supply of the public grid and ensuring that the electricity is fed into the grid in accordance with the regulatory requirements of the grid operator. The device constantly monitors the power quality and grid voltage and adjusts the power production accordingly to ensure a stable and reliable power supply.
Grid fees are charges incurred for the use of electricity grids. They cover the costs of operating, maintaining and expanding the electricity transmission and distribution grids. These grids transport the electricity from the producer to the consumer. The grid fees are charged by the grid operators and make up a significant part of the electricity price. They vary depending on the region and grid operator and are passed on to the end consumer. There are no grid fees for PV systems for own use. More on this topic in our report Electricity grid fees are rising rapidly.
The grid impedance is the electrical resistance of the power grid, including all cables, lines, switchgear and transformer stations. It is measured in ohms and describes the resistance that an electric current can experience in the grid.
The grid impedance influences the voltage and current flow in the power grid and is an important factor in the planning and operation of electrical grids. A high grid impedance can lead to higher losses in the grid, lower voltages and reduced efficiency.
Grid connection or grid-connected photovoltaic systems refers to the connection of a photovoltaic system to the public electricity grid. This means that the direct current generated by the solar modules is converted into alternating current by the inverter and fed into the public grid.
Grid coupling makes it possible to use the electricity generated by the PV system and feed surplus electricity into the grid if the PV system produces more electricity than is needed. If required, the electricity can then be drawn from the grid again.
Grid feed-in refers to the feeding of electricity from renewable energy sources such as photovoltaic or wind power plants into the public electricity grid. The direct current generated by the renewable energy sources is converted into alternating current by an inverter and fed into the grid.
Feeding renewable energies into the grid is an important step towards a sustainable energy supply and the reduction of CO2 emissions. By feeding renewable energies into the grid, they can be integrated into the public electricity network and the electricity demand of consumers can be covered.
Grid compatibility refers to the ability of electricity generators to integrate their generated electricity into the public grid without compromising the stability, reliability or efficiency of the grid. Grid compatibility is often discussed in the context of renewable energies such as photovoltaic or wind power plants, which can pose challenges for grid integration due to their volatile and intermittent power generation.
Grid compatibility depends on various factors, such as the type of power generation technology, the grid structure, grid control and the regulation of grid feed-in devices. Grid operators must ensure that the power generated by electricity generators meets the requirements of the grid code and does not have a negative impact on grid stability. This can be achieved through regulations such as the feed-in tariff, incentives for the use of battery storage or the use of smart grid technologies.
Good grid compatibility is crucial for a safe, reliable and efficient power supply and an important step towards a sustainable energy supply.
The grid compatibility test (NVP) is a procedure that is generally used in the field of energy supply, particularly in connection with the expansion of electricity grids. The aim of the grid compatibility test is to assess the impact of new energy generation plants or large consumers on the existing electricity grid.
Various factors are taken into account, such as the stability of the grid, the security of the energy supply, the integration of renewable energies and the economic viability of the grid expansion. The assessment is usually carried out by the grid operators or the relevant authorities and can cover various aspects, from technical analyses to environmental impact assessments.
The aim is to ensure that new systems or consumers can be integrated into the existing electricity grid without negative effects, while at the same time guaranteeing a reliable and efficient energy supply.
Find out more in our article: Grid compatibility test (NVP) for large-scale PV systems
There are various reasons why an emergency shutdown can be carried out on a system. In connection with photovoltaic systems, emergency shutdowns occur in the following cases, for example:
If a PV system is overloaded or overheated: If the system is overloaded or overheated, this can lead to an emergency shutdown to prevent damage to the system.
In the event of a power failure in the grid: If there is a power failure in the public grid, an emergency shutdown of the system may be necessary to prevent electricity from being fed into the grid and endangering workers working on the grid.
During maintenance work on the PV system: During maintenance work on the system, it may be necessary to switch off the system briefly to ensure the safety of maintenance workers.
In the event of a fault in the system: If a fault occurs in the system, an emergency shutdown may be necessary to prevent further damage to the system or to prevent electricity from being fed into the grid that does not meet the specified requirements.
Emergency power refers to the power supply in emergencies or power outages. This means that an alternative power supply is available to keep important systems or devices running if the public power grid fails or is unavailable.
PV systems always supply electricity regularly and reliably. If they are also equipped with storage systems, this electricity can also be used as emergency power if the public grid should fail.
Otherwise, emergency generators are also often a source of emergency power. These generators can run on either fossil fuels such as diesel or gas.
T - V
The diurnal cycle describes the course of solar energy during the day. Solar energy varies throughout the day due to the movement of the sun in the sky and other factors such as weather conditions.
Solar energy typically reaches its peak at midday, when the sun is at its highest. At this time, the angle of the sun's rays is most favorable for generating maximum energy. Before and after midday, however, solar energy can vary depending on location, season and weather conditions.
Tandem solar cells are a type of solar cell that consists of several layers of semiconductor materials. In contrast to conventional solar cells, which only have one layer of semiconductor material, tandem solar cells have two or more layers that are stacked on top of each other and electrically connected.
The idea behind tandem solar cells is that each layer is able to absorb a certain range of the solar spectrum more efficiently than a single layer. By combining several layers, each of which is optimized for different wavelength ranges, the efficiency of the solar cell can be increased. Tandem solar cells can therefore achieve higher efficiencies than conventional solar cells.
There are various approaches to producing tandem solar cells, including the use of different semiconductor materials in each layer or the use of multiple layers of the same material with different doping levels. The development of tandem solar cells is an active field of research and there are many promising advances in this area.
The EU taxonomy is a set of rules developed by the European Union as part of the "Action Plan on Financing Sustainable Growth". It defines uniform criteria and standards for classifying economic activities in terms of their environmental impact. The main objective is to support investors and companies in identifying sustainable activities and directing investments into these areas. The taxonomy covers six environmental objectives, including climate change mitigation, climate change adaptation and biodiversity protection. Companies, banks, insurance companies and funds are obliged to disclose the sustainability characteristics of their activities. The EU taxonomy will be introduced gradually and will become part of transparent sustainability reporting for larger companies. By complying with CSR reporting requirements and investing in sustainability, companies can gain a competitive edge and make it easier to raise capital.
More on the topic EU taxonomy in our report.
TCFD stands for Task Force on Climate-related Financial Disclosures. It is a working group set up by the Financial Stability Board (FSB), which was established in 2015. The TCFD aims to develop uniform standards for the reporting of climate-related risks and opportunities in financial reports.
TCFD reporting refers to the disclosure of information on the impact of climate change on a company's financial performance. This reporting includes aspects such as the analysis of climate risks, the integration of climate scenarios into the corporate strategy, the disclosure of greenhouse gas emissions and measures to adapt to climate change.
By companies publishing TCFD reports, investors and other stakeholders can better understand how well prepared a company is for the risks and opportunities associated with climate change. This can help to better assess long-term financial risks and make investment decisions that take climate change into account.
Find out more in our report on TCFD reporting.
The temperature coefficient for solar modules describes the change in the output of a solar module as a function of temperature. In general, the output of solar modules decreases at higher temperatures.
The temperature coefficient is normally given as a percentage per degree Celsius (°C). A negative temperature coefficient means that the output of the solar module decreases as the temperature increases. A typical value for the temperature coefficient of the output of a solar module is between -0.3 %/°C and -0.5 %/°C.
It is important to take the temperature coefficient into account when planning and installing solar modules, as high temperatures can affect the performance of solar modules. A higher operating temperature of the solar module can lead to a lower yield, especially in regions with high temperatures.
A thermoelectric generator (TEG) is a device that converts heat into electricity. In solar cells, a TEG is typically used to exploit the temperature difference between the front and back of a solar cell to generate additional electricity. However, the principle also works with the temperature fluctuation between day and night. It is based on the so-called Seebeck effect, named after the German physicist Thomas Johann Seebeck. This effect occurs when two different metals are joined together and there is a temperature difference between the two joints. In this case, a voltage is created between the metals that is proportional to the temperature difference.
To utilize the Seebeck effect in solar cells, several solar cells are usually connected in series and connected to a TEG. The solar cells generate heat on the front and release it on the back. The TEG utilizes the temperature difference between the two sides and generates additional electricity.
There are various types of TEGs based on different materials and technologies. However, the efficiency of TEGs is still relatively low and their use is often limited to special areas of application, such as space travel, military applications or surveillance systems.
The GHG quota is a government regulation that serves to reduce greenhouse gas (GHG) emissions and increase the use of renewable energies. It is a mandatory quota for the use of biofuels in traffic and transportation.
The GHG quota obliges oil companies to place a certain quantity of biofuels on the market and reduce the amount of greenhouse gases emitted. The quota usually increases annually and is set by the respective national legislators.
The introduction of the GHG quota is intended to reduce CO2 emissions and increase the use of renewable energies in the transport sector. It should also help to reduce dependence on fossil fuels and reduce environmental pollution.
In photovoltaics, TMY refers to representative weather data that simulates an average year for a location. This data, based on long-term weather records, includes parameters such as solar radiation, temperature and wind speed. They are used to plan and forecast the yield of solar installations, as they realistically represent typical climatic conditions.
Load reserves refer to the difference between the actual load and the maximum permissible load of a component or structure. These reserves are important to ensure that a component or structure does not fail under unforeseen or exceptional loads.
Load reserves are usually taken into account in the design and calculation of components and structures to ensure sufficient safety and reliability. This is particularly important in areas such as construction, aerospace or the automotive industry, where the safety of human life depends on the reliability and load-bearing capacity of components and structures.
The load reserves are often expressed as a ratio between the actual load and the maximum permissible load. For example, a safety factor of 2 means that the maximum permissible load is twice as high as the actual load.
Disconnectors are safety devices in photovoltaic (PV) systems that are used to interrupt the circuit of the PV modules. They make it possible to disconnect the modules from the rest of the electrical system, for example for maintenance or repair purposes. Disconnectors can be operated manually and offer a simple way to safely shut down the PV system. They are an important part of the safety equipment in PV systems to prevent electrical accidents and carry out maintenance work safely.
More about Disconnectors in our report.
The Technical Connection Conditions (TAB) for photovoltaic systems in Germany define the minimum requirements for connecting photovoltaic systems to the electricity grid. They serve as a guideline for grid operators and installers to ensure the safe and reliable integration of PV systems into the electricity grid.
The TAB contain technical specifications for the design, connection and operation of PV systems. These include requirements for protective devices, voltage frequency monitoring, grid and system protection and connection to the public grid.
Compliance with the TAB is mandatory for connecting the PV system to the electricity grid and must be checked by an expert. The costs for the inspection and the necessary adjustments to the system may vary depending on the federal state and grid operator.
Overvoltage protection for photovoltaic systems (PV systems) is an important part of the protection concept for the system and serves to protect the connected devices and components from overvoltages that may occur during operation of the system.
Overvoltages in a PV system can be caused by various factors, including lightning strikes, inverter malfunctions or switching operations in the power grid. These surges can cause PV system components to be damaged or destroyed, leading to downtime and expensive repairs.
To avoid this, overvoltage protection is required for PV systems. This protection can be installed in the form of lightning protection systems, surge arresters or other devices that are integrated into the PV system. These devices discharge the excess voltage from the PV system and thus protect the connected components.
The amount of VAT for solar system operators depends on various factors, including the type of system, the location and size of the system and the way in which the electricity is marketed.
In general, income from the sale of solar power by the operator is subject to VAT of currently 19% in Germany. However, various regulations are currently being discussed as part of the Renewable Energy Sources Act, the climate targets and the electricity price brake to reduce the tax rate for systems of different sizes.
If the operator runs a photovoltaic system for their own use, no VAT is due, as self-supply is exempt from VAT. In this case, however, the operator must bear the investment costs of the system and cannot receive any remuneration for the electricity fed into the grid.
It is important to note that VAT regulations may vary depending on the country and region and it is advisable to consult a tax advisor or a specialist tax lawyer to obtain accurate information.
Choosing the right substructure is crucial, as it influences the stability and safety of the system. There are different types of substructures, such as on-roof, in-roof and free-standing systems. These must withstand various loads, such as gravity, wind, snow and temperature. The choice of substructure also influences the roof load, which must be taken into account when installing PV systems. Other factors such as site conditions, aesthetics and budget also play a role. Careful selection ensures a safe and efficient PV roof system.
More about suitable substructures in our report.
A UPS (uninterruptible power supply) is an electrical device that is used to protect critical electrical loads in companies, data centers or private households from power failures, voltage fluctuations and other power problems.
A UPS typically consists of a battery and an inverter that converts the battery's DC voltage into AC voltage. In normal operation, the power from the socket is used, but if there is a fault in the power grid, the UPS automatically switches to the power supply from the battery and supplies the connected devices with power.
The aim of a UPS is to ensure that the connected devices continue to be supplied with power even in the event of a power failure in order to ensure smooth operation and protection against data loss or damage to sensitive devices.
The size and capacity of a UPS depends on the user's requirements, such as the number of devices to be protected, the required power capacity and the expected duration of power outages. UPS systems can also be equipped with additional functions such as automatic diagnostics and maintenance, monitoring of power consumption and protection against overload and overheating.
In the context of photovoltaics and energy storage systems, valley filling refers to the period of low consumption when an energy storage system is refilled with cheap PV electricity. Basically, it is the opposite of peak shaving.
VDE stands for "Verband der Elektrotechnik Elektronik Informationstechnik e.V." and is a leading technical-scientific organization in Germany that deals with the promotion and development of electrical engineering, electronics and information technology. The association has its headquarters in Frankfurt am Main and has several regional and international branches.
The activities of the VDE include the development of norms and standards for electrical engineering, the certification and testing of electrical and electronic devices, the education and training of specialists, the promotion of research and development and the support of innovations in electrical engineering and electronics.
Vehicle to Grid (V2G) refers to the technology that enables an electric vehicle to feed electricity back into the grid when it is not in use, thus becoming a source of energy for the grid.
This technology enables electric vehicles not only to consume electricity, but also to act as mobile energy storage units. When an electric vehicle is connected to the power grid and not in use, it can feed excess energy back into the grid. This allows the grid to be stabilized when needed and electricity demand to be covered.
V2G is a promising technology that has the potential to facilitate the integration of renewable energies into the electricity grid and to make the electricity grid more efficient and flexible.
Further information in our article Vehicle to Grid (V2G) & bidirectional charging
The connection point (also known as the connection point or grid connection point) for PV systems refers to the point at which the PV system is connected to the electricity supplier's electricity grid. The connection point is therefore the transition point between the PV system's own electricity generation and the public electricity grid.
Shading on solar modules occurs when the solar cells are partially or completely covered by shade. Shading can impair the efficiency of solar cells or entire photovoltaic systems, as it reduces the amount of sunlight that reaches the cells and thus reduces electricity production.
If one or more solar cells of a photovoltaic system are shaded, this significantly reduces the electricity production of the entire system, as the shaded cells form a resistance and reduce the electricity production in the other, unshaded cells. In order to minimize the effects of shading on the electricity production of a photovoltaic system, so-called optimizers or power optimizers are often used, which can monitor and optimize each solar module separately.
Although photovoltaic insurance is not compulsory in Germany, it is extremely useful in the commercial sector, as it covers not only repairs but also loss of income or operating losses in the event of damage. Typical causes of damage are hail, storms, lightning strikes, theft, vandalism and technical faults. The insurance covers damage to solar modules, inverters, cabling, energy storage systems and other components of the PV system. It also covers yield and operating losses as well as additional costs during the repair period. The premiums for photovoltaic insurance are relatively low in relation to the potential damage and investment costs and are therefore worthwhile for companies.
More on the topic Insurance for photovoltaics in our article.
Volatile energy sources are energy sources whose availability fluctuates and is unpredictable. This means that their production is not constant and can fluctuate depending on weather conditions or other factors. Examples of volatile energy sources are wind energy and solar energy, as their production depends on factors such as wind strength, solar radiation and cloud cover.
Other energy sources such as coal, oil and gas are relatively constant and reliable compared to volatile energy sources, as they can produce continuously regardless of environmental conditions. This is one of the reasons why integrating volatile energy sources into the energy system is a challenge, as the fluctuating production of wind and solar energy is often not synchronized with the constant demand for energy. To overcome this challenge, energy storage systems and intelligent power grids (smart grids) are used to store the surplus energy and retrieve it when needed.
Full feed-in is a term used in the field of photovoltaics and refers to the direct feed-in of all the solar power produced into the public electricity grid. This means that all the energy generated by the photovoltaic system is fed into the grid and remunerated.
With full feed-in, the electricity produced by the photovoltaic system is not used to cover your own electricity requirements, but all the electricity is fed into the grid and remunerated. The electricity supplier remunerates the electricity fed into the grid depending on the feed-in tariff or current market prices.
Full feed-in is one way in which the operator of a photovoltaic system can generate income and contribute to the promotion of renewable energies. However, it is also possible to use some or all of the solar power you produce yourself in order to cover your own electricity requirements and thus reduce your electricity costs.
VSME sustainability reports are reports from very small and medium-sized enterprises (VSMEs) that document their sustainability practices and performance. They contain information on environmental, social and economic aspects of corporate governance and show how these companies contribute to sustainable development.
Find out more in our report on LSME and VSME sustainability reports.
B
A backsheet is an important component of solar cell modules and is a protective layer on the back of the solar panel. It protects the sensitive electrical components of the panel, especially the solar cells, from environmental influences such as moisture, UV radiation and extreme temperatures.
The backsheet is usually made of a durable plastic material such as ethylene vinyl acetate (EVA), polyvinyl fluoride (PVF) or polyethylene terephthalate (PET). These materials are durable, waterproof and resistant to the environmental influences that affect solar installations.
There are also different types of backsheets that can be selected depending on the requirements and conditions of the installation. For example, some backsheets can be thermally reinforced to improve temperature tolerance and durability, while others contain an additional layer of aluminum foil to prevent moisture ingress.
Overall, the backsheet is an important component of a solar panel that helps to ensure that the solar system works efficiently and reliably for many years.
A ballast system is a special form of elevation and is used for flat roofs. A major advantage of the ballast system is the fact that the roof cladding does not have to be penetrated. Instead, a substructure is created, which can be weighted down with stones or concrete slabs, for example. The solar modules can then be installed on this substructure - without further drilling or fastening.
The band load is a constant load and is maintained by band current. Both terms are used in the energy and electricity industry and apply to constant consumption and constant electricity generation. They are not identical to the terms "base load" or "base current". These only describe the minimum electrical load or base load.
More about Strip load & strip current
Battery storage systems offer a wide range of benefits to industry. They make it possible to reduce expensive peak loads by using electricity from the storage system instead of from the grid when demand is high. They also contribute to grid stability by providing balancing energy at short notice. Another benefit is the optimization of self-consumption: surplus electricity from own renewable sources such as solar energy can be stored and used later, which reduces the need to purchase additional grid electricity. Battery storage systems also serve as an emergency power supply to maintain important processes in the event of grid failures. These advantages lead to cost savings, greater security of supply and also support the energy transition. You can find an overview on our page Large-scale battery storage.
Only with a battery inverter can power storage units be integrated into the entire operational power grid. This is necessary because batteries or power storage units can only store DC currents or direct current. As a rule, however, power grids are AC systems and supply machines and all power consumers with alternating current.
A battery management system is a battery monitoring system that controls key operating parameters during charging and discharging such as voltages and currents as well as the internal and ambient temperature of the battery. The monitoring circuits usually provide inputs to protection devices that trigger alarms or disconnect the battery from the load or charger if any of the parameters are outside the limits.
A BMS is essential for the energy or plant engineer who is responsible for the emergency power supply and who uses the battery against a power outage, a telecommunications network failure or simply for operational peak shaving. Such systems include not only monitoring and protection of the battery, but also methods by which it can deliver full power when required, as well as methods to extend its life. This ranges from controlling the charging process to scheduled maintenance.
Entire EMS (energy management systems) such as the CUBE EfficiencyUnitare also able to control large battery storage systems.
Individual solar modules and entire commercial photovoltaic systems must pass various load tests before they are connected to a power grid. In the case of modules, these load tests are carried out by the TÜV before the modules are placed on the market and in the case of individual PV systems, a test is carried out in accordance with DIN EN 62446-1 and VDE 0126-23-1.
With operational management or technical management, a commercial photovoltaic system is "handed over". This means that the company's employees receive onboarding for the entire PV system to ensure that smooth and efficient operation is guaranteed. Of course, CUBE CONCEPTS is available to answer any questions the client may have afterwards.
BESS are battery storage systems that go beyond the mere storage of electricity. At the very least, they are characterized by battery management systems and regulate energy flows in companies. Find out more in our article: BESS as a smart solution for energy systems.
The reference meter is the counterpart to the feed-in meter. It measures the amount of electricity that is fed into the company grid from the public grid.
Bifacial solar modules are photovoltaic modules that can convert solar radiation into solar power on both sides. On the one hand on the side facing the sun and on the other on the shaded side. The indirect and diffuse light should also be used. The level of additional yield depends on the module properties as well as the type of installation and the surroundings of the PV system.
More about bifacial PV modules in our report.
Lead-acid batteries are electricity storage devices in which the electrodes are made of lead or lead dioxide and the electrolyte is diluted sulphuric acid. They were state of the art in the past, are relatively inexpensive and reliable for several years. However, they are heavy and the energy density is not particularly high. Today, more modern lithium-ion batteries or long-life LiFePO4 batteries are used, the prices of which have fallen sharply in recent years and are generally considered to be safer and more powerful.
Reactive current refers to the current that flows in an electrical circuit without any electrical power (in the form of work or energy) being transferred. It occurs when an alternating voltage is applied to an inductive or capacitive load. These loads can generate magnetic fields (inductances) or electric fields (capacitances) that influence the current flow without any work being done. The reactive current and the associated reactive power are important for calculating the total power in an electrical network, especially when it comes to efficiency, power factor and the design of circuits.
Read more in our report Reactive current for PV systems.
Lightning can damage PV systems, which is why they must be protected from lightning strikes. This is done using lightning conductors and at the same time by earthing the frames and mounting racks. DIN EN 62305-3 Supplement 5 and VDE 0185-305-3 Supplement 5 must be observed and, according to VdS 2031, there must be a sufficient separation distance between the DC cable and the lightning protection system.
The Balance of System (BOS) is a type of bill of quantities and includes all components of a photovoltaic system other than the photovoltaic modules, including cabling, switches, a mounting system, one or more solar inverters, a battery bank, a battery charger, etc.
Other optional components include the reference and feed-in meters, battery inverters, GPS solar trackers, energy management software, solar radiation sensors, anemometers or task-specific accessories developed to meet a system owner's specific requirements.
For large photovoltaic power plants or solar parks that are installed on the ground, components and installations such as grid connections, offices and concrete are also required. This is also considered as part of the bill of quantities.
The Federal Network Agency is an independent federal authority in Germany responsible for regulating telecommunications, energy, postal services and railroads. It is also responsible for promoting the expansion of renewable energies. It is responsible for the approval and monitoring of renewable energy plants such as solar and wind power plants and ensures a secure and stable power supply.
The Bundesverband Energiespeicher Systeme e.V. (BVES) is an association of companies and institutions active in the energy storage sector. BVES was founded in 2012 and now represents over 200 members from various sectors, including manufacturers, project developers, system integrators and research institutions.
The BVES aims to promote the market development of energy storage systems in Germany and Europe and to represent the interests of its members. To this end, the association is involved in various areas, such as political lobbying, public relations and the promotion of research and development.
One focus of the BVES's work is the creation of framework conditions for the use of energy storage systems that support the expansion of renewable energies and the increase in energy efficiency. To this end, the association advocates an effective and technology-open energy policy and works closely with political decision-makers, associations and other stakeholders.
The bypass diode is a semiconductor diode that ensures that the current continues to flow between the solar modules even when no current is flowing in a solar cell. It therefore redirects the current. This happens when individual modules are dirty, shaded or defective. If no bypass diode is used, a hotspot can occur at these points and result in the entire PV system hardly producing any electricity or individual modules being damaged.
With bidirectional charging, the electric car's power storage unit is not only used for e-mobility, but also serves as an energy supplier for internal stationary consumers. The batteries of the e-vehicles are therefore used as buffer storage for the entire company. This technology makes perfect sense as a peak-shaving tool in combination with photovoltaic systems, although there are currently hardly any suitable cars, wall boxes or charging infrastructures. In addition, the legal regulation has not yet been defined and there are no standards and regulations yet.
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Large commercial and industrial flat roofs in particular are ideal for generating electricity cheaply and ecologically using solar systems, as they are usually unshaded and the energy produced is consumed directly on site. Flat roofs are very suitable for PV systems, actually have a gradient of at least 2 % and are usually bitumen or foil roofs. They are often filled with gravel or
greened. Under the bitumen, PVC or FPO foil, they are usually insulated with polystyrene or rock wool. As with all roof types, existing
properties with flat roofs, a structural analysis must first be carried out.
The area efficiency of renewable energies refers to how effectively renewable energy sources can generate energy on a given area. It is a measure of how much energy can be generated per unit area.
Space efficiency varies depending on the type of renewable energy source. Some renewable energy sources, such as solar and wind energy, can generate large amounts of energy on relatively small areas, while others, such as biomass, may require more area to generate the same amount of energy.
For example, solar systems have a high area efficiency as they can be installed on roofs or open spaces and can convert sunlight into electricity. Wind turbines also have good space efficiency, as they can be placed on relatively small plots of land and can convert wind into electrical energy.
Land efficiency is an important factor in the evaluation and planning of renewable energy projects, as it helps to select the best sites and technologies to maximize the energy yield from the available land.
To our contribution Area efficiency of PV systems in comparison.
The surface load for roofs refers to the maximum load that a roof can bear without being damaged or collapsing. The surface load depends on the type and load-bearing capacity of the roofing material and is usually specified in kilograms per square meter (kg/m²).
When installing solar systems on roofs, the surface load is an important factor, as the additional weight of the solar panels and mounting systems can increase the load limit of the roof. Too high a surface load can lead to structural damage and damage the roof or even the entire building.
The surface load can vary depending on the location and roof type. In regions with high snowfall or heavy rainfall, the surface load must be higher than in regions with a mild climate. The load-bearing capacity of the roof also depends on the pitch, the age and condition of the roof and the type of construction.
It is important that when installing solar panels on roofs, the distributed load is carefully calculated to ensure that the roof can support the additional load. A professional solar engineer can calculate the surface load and select suitable mounting systems to ensure the stability and safety of the solar installation and the roof.
Flexible solar modules are the right choice for slightly curved surfaces, or if you really want to save every gram of weight. As a rule, they are not used in commercial photovoltaic systems that are intended to provide reliable solar power for decades. A common application is, for example, use on mobile homes or campers.
A foil roof usually consists of bitumen, PVC or FPO foil and is usually insulated with polystyrene or rock wool. Foil roofs are usually flat roofs and are therefore well suited to installing photovoltaic systems on them, as the flat surface means that they are not exposed to the sun.
side of the roof and the solar modules can be optimally aligned using an appropriate elevation. With flat roofs, the entire roof surface is usually available for a PV project.
Various subsidies are available for commercial photovoltaic systems, whether rooftop, ground-mounted or carport systems. This also applies to all investments in e-mobility for companies. Although investing in a PV system is always extremely economical, even without subsidies, all subsidy options should be checked and individually evaluated in advance. This is not always easy, as there are many different regional subsidy programs for renewable energies in Germany. CUBE CONCEPTS will be happy to advise you on all questions regarding funding opportunities.
Photovoltaics on open spaces are also known as solar parks. This allows companies to use their unused land extremely economically and profitably. This not only saves energy costs and reduces the carbon footprint, but also ensures sustainable climate and environmental protection. Studies have shown that these highly efficient PV systems are also very worthwhile from an ecological perspective, as they provide habitats and retreats for plants and animals and promote the biological regeneration of the soil.
A radio ripple control receiver is a device used in the energy industry to control the output of decentralized generation systems. The radio ripple control receiver receives commands from a central control system via a radio signal, which can increase or decrease the output of the generation system.
The use of radio ripple control receivers is particularly relevant in the context of grid stabilization measures such as the redispatch procedure. Here, grid operators can temporarily limit or increase the output of decentralized generation plants in order to avoid bottlenecks in the electricity grid. The use of radio ripple control receivers enables grid operators to quickly and flexibly adjust the output of decentralized generation plants without the need for direct access to the plants.
Radio ripple control receivers are used, for example, in photovoltaic systems, wind turbines or combined heat and power plants. They are generally easy to install and operate and can help to increase grid stability and facilitate the integration of renewable energies into the power grid.
The generator that connects the PV system to the power grid is installed in the generator connection box. The generator junction box serves as an interface between the generator and the electrical network that distributes the electrical energy.
The generator connection box can have different functions, depending on the requirements of the respective grid operator or customer. As a rule, it contains switching and protection components, such as circuit breakers, overcurrent protection, voltage regulators or power meters.
The generator connection box is important to ensure a safe and reliable connection between the generator and the network. It also helps to monitor the power quality and ensure that the generator is operating within the specified limits.
The Building Electromobility Infrastructure Act (GEIG) is a ground-breaking legal regulation that promotes the expansion of the electric mobility infrastructure. Charging infrastructure for electric vehicles in German buildings in accordance with the European Buildings Directive EPBD 2018 through a mandatory charging infrastructure. More on the topic in our article here GEIG charging infrastructure obligation for companies.
Production costs are the costs incurred for the production of a unit of energy (e.g. one kilowatt hour of electricity). They include all expenses such as investment costs, operating costs, fuel costs and maintenance. The production costs are an important factor in comparing the profitability of different energy sources, such as wind power, solar energy or fossil fuel power plants.
You can find an overview of the various prime costs in our report PV electricity generation costs in comparison or Production costs for PV battery systems.
Direct current (DC) is an electric current that flows in one direction and whose current and voltage are constant. In contrast, with alternating current (AC), the direction of the current changes periodically.
Direct current is used in many applications, such as batteries, accumulators and solar modules. Electronic devices that are powered by batteries, such as cell phones or laptops, use direct current. Electric motors and electric vehicles can also be powered by direct current.
Direct current has the advantage that it is easy to generate and control. It is often considered to be more stable and safer than alternating current as it has no voltage peaks. However, the disadvantage of direct current is that its constant current flow makes it unsuitable for transportation over long distances, as it loses energy due to the electrical resistance in the lines. In such cases, alternating current is used as it can be brought to a higher voltage with the help of transformers and can therefore be transmitted more efficiently.
In photovoltaics (PV), global radiation refers to the amount of sunlight that hits a certain area on the earth's surface. It is made up of direct solar radiation and scattered diffuse radiation.
Direct solar radiation reaches the earth's surface in a straight line and is not scattered or absorbed by the atmosphere. It depends on the position of the sun in the sky and is influenced by the formation of shadows. Scattered diffuse radiation, on the other hand, occurs when sunlight is scattered by the atmosphere and distributed over the earth's surface.
Global radiation is an important parameter in the planning and operation of PV systems, as it measures the amount of available sunlight on the earth's surface. PV systems convert sunlight into electrical energy, whereby the power yield of the system depends on the amount of incident radiation. The higher the global radiation, the more energy the PV system can produce.
Global radiation is usually measured in watts per square meter (W/m²) and can be recorded by measuring devices such as pyranometers. The measured values of global radiation are often transmitted in real time to control and monitoring systems of PV systems in order to optimize the energy production of the system and to react to changes in radiation.
In energy supply, the base load refers to the minimum energy requirement that must be continuously covered by an electricity grid or a specific consumer. This minimum requirement is independent of fluctuations in electricity demand and is covered by a specific type of consumer, such as heating systems, cooling systems or lighting systems. The base load can fluctuate depending on the time of day or year, day of the week or public holiday, but it remains within a certain range. More about the Base load in our article.
GWh stands for gigawatt hour. It is a unit of electrical energy used to measure large amounts of electricity generated, transmitted or consumed in a given period of time. One GWh corresponds to one billion watt hours.
A watt is a unit of power that indicates how much energy is consumed or generated per second. One watt corresponds to one joule per second. A watt-hour (Wh) is a unit of energy that is produced when one watt is used or generated for more than one hour. A kilowatt-hour (kWh) is equal to 1000 watt-hours and is often used to measure the electricity consumption of a household or small business.
GWh is often used to measure the electricity production of power plants or the electricity supply of entire countries. For example, total electricity generation in Germany in 2020 amounted to around 510 GWh. The GWh is also an important unit in the planning of renewable energy projects such as wind farms or solar plants, as it indicates the amount of electricity generated that can be fed into the grid.
A semiconductor is a material whose electrical conductivity is between that of a conductor (such as copper) and a non-conductor (such as glass). Semiconductors are important materials in the electronics industry and are used in many electronic devices, such as transistors, diodes and solar cells.
Semiconductors are usually made up of elements from the third to the fifth group of the periodic table, such as silicon, germanium, arsenic and gallium arsenide. A semiconductor has a specific electrical resistance that lies between that of a conductor and a non-conductor. By introducing impurities (doping), the conductivity of the semiconductor can be specifically increased (p-doping) or decreased (n-doping).
The electrons in a semiconductor can be excited by an external energy source (e.g. a voltage source) to jump from the valence band to the conduction band. In doing so, they leave a gap (hole) in the valence band. In a p-doped semiconductor, the holes move through the crystal, while in an n-doped semiconductor the electrons flow through the crystal. This behavior allows semiconductors to be used in electronic components such as transistors, which act as switches and amplifiers.
The properties of semiconductors have led to numerous developments in the electronics industry and play an important role in many areas of everyday life.
Modern heating systems such as heat pumps or infrared heaters can be operated using inexpensive PV electricity. Both variants have advantages and disadvantages. A good overview is provided in our article "Heating with photovoltaics“.
Guarantees of origin for green electricity, also known as "green certificates" or "guarantee of origin systems", are documents that prove that a certain amount of electricity has been generated from renewable energy sources. Each guarantee of origin corresponds to one megawatt hour (MWh) of renewably generated electricity.
These guarantees of origin serve to prove the origin and ecological added value of the electricity generated. Companies that use or want to sell green electricity can purchase these guarantees to ensure that the electricity they use or sell actually comes from renewable sources. The use of guarantees of origin enables companies to label their electricity consumption as "green" and prove to their customers that they are contributing to the promotion of renewable energy.
Guarantee of origin systems vary depending on the country and region, but their purpose is to create transparency and trust in the origin of green electricity and to support the expansion of renewable energies.
More about trading Guarantees of origin and how energy producers benefit from it.
The purpose of rear ventilation of solar modules is to increase the performance and durability of the modules and to reduce heat generation.
If solar modules are installed in direct contact with a roof or other surface, heat can accumulate under the modules. If the modules become too hot, their performance may decrease or they may even be damaged. In addition, a high temperature can reduce the service life of the electrical components.
The rear ventilation ensures that air circulates between the modules and the surface below. This dissipates the heat generated by the modules and keeps the module temperature lower. A lower operating temperature of the modules generally leads to higher efficiency and a longer service life of the electrical components.
Rear ventilation can be realized in various ways. One option is to place the solar modules on special mounting systems that create a ventilation layer between the modules and the surface below. Another option is to integrate air ducts into the mounting system to improve air circulation. Rear ventilation can also be taken into account when planning solar power plants, for example by leaving gaps between rows of solar modules to allow effective ventilation.
A hotspot is a problem that can occur with solar modules if part of the module is not sufficiently exposed or fails while the rest of the module continues to generate electricity. This can happen if one or more cells in the module are damaged or blocked, for example due to soiling, shading or wiring faults.
If a cell is blocked or damaged, the current produced by the other cells in the module can be diverted to this cell, which can lead to the cell overheating. If the overheating is high enough, this can lead to destruction of the cell, which can reduce the performance and service life of the entire module.
A hotspot can be detected by regular inspections of the solar panels using an infrared camera to detect hot spots. To avoid hotspots, it is important that solar panels are carefully installed and maintained to ensure that they are evenly exposed and free from blockages and defects. It is also important to choose high-quality solar panels that are less likely to develop hotspots, as well as to use reliable inverters and monitoring systems to detect and fix problems quickly.
A hybrid inverter is a device that is used in solar power systems and combines the functions of conventional solar inverters and battery inverters. Hybrid inverters enable solar power to be stored in batteries and the stored power to be used when required.
Hybrid inverters can be used in grid-connected or off-grid systems. In grid-connected systems, the surplus solar power is fed into the public grid, while in off-grid systems, all the solar power is stored in batteries and used when required.
A hybrid inverter can control the flow of electricity by storing solar power in the batteries when demand is low and releasing the stored power when demand is high or the sun is not shining. This enables maximum use of the solar power generated and can help reduce electricity consumption and reduce dependence on fossil fuels.
Hybrid inverters are usually equipped with intelligent control systems that can monitor and regulate battery power and grid connection power. Some hybrid inverters also offer functions such as emergency power supply, which can enable the operation of certain devices in the event of a power failure, as well as integrated chargers for electric vehicles.
The official commissioning date of a solar energy system is the date on which the system is fully installed and operational. This is the time at which the system can generate electricity and feed it into the grid if it is a grid-connected solar system.
See also roof integration. In-roof mounting of photovoltaic systems refers to the installation of solar cells into the roof structure of a building. Instead of installing separate solar cells on a roof or on a free-standing frame, the solar cells are integrated directly into the roof cladding to create a more aesthetic and seamless solution.
A solar island system is an independent photovoltaic system that is not connected to the power grid but acts as a self-sufficient power supply. It is also referred to as an off-grid system. Such a system usually consists of photovoltaic modules, a charge controller, batteries and an inverter to convert the direct current from the batteries into alternating current that can be used to operate electrical appliances.
Intersolar is the leading trade fair for the solar industry and all partners aiming to actively promote the development of solar technology. Under the motto "Connecting Solar Business", manufacturers, suppliers, wholesalers, service providers, project developers and planners as well as start-ups from all over the world meet annually in Munich to discuss the latest developments and trends, experience innovations at first hand and exploit business potential.
An inverter is an electronic device that converts direct current (DC) into alternating current (AC). Inverters are used in many applications, including solar power systems, wind turbines, UPS systems, power supplies and electric motors.
DIN EN ISO 50001 is an international standard for energy management systems that helps companies to improve their energy efficiency, cut energy costs and reduce their environmental footprint. The standard defines requirements for an energy management system, including the development and implementation of an energy policy, setting energy targets and continuous improvement processes. ISO 50001 certification offers companies several advantages, including exemption from the energy audit obligation under the Energy Services Act (EDL-G) and increased competitive advantages through a positive image. Smaller companies can also benefit from certification by increasing their energy efficiency and reducing costs. Other benefits include compliance with legal guidelines, promotion of sustainability, image improvement and facilitation of cooperation with customers and suppliers.
More about ISO 50001 in our article.
The term "annual variation" refers to the seasonal fluctuations in a company's energy consumption and energy costs. This seasonal variation is an important aspect of energy efficiency and energy management in companies. The analysis and management of a company's seasonality are important steps in reducing energy costs, minimizing environmental impact and increasing operational efficiency. Companies can achieve this by introducing energy-efficient technologies, monitoring energy consumption patterns and adapting their energy procurement strategies to the annual cycle.
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An off-grid system is a stand-alone system. This refers to a PV system that is not connected to the public power grid. The solar power is consumed directly on site. Off-grid systems are generally used in private and smaller environments, such as in vacation homes, mountain huts, boats or mobile homes. Large commercial photovoltaic systems are usually on-grid systems and have a fixed connection to the public electricity grid.
On-grid PV systems are solar installations that are connected to the public grid. Commercial photovoltaic systems are usually always connected to the existing public grid, as they also feed electricity into the grid when it is not being consumed during operation. On-grid systems are therefore always equipped with an inverter and are able to feed surplus electricity into the public grid at weekends, for example, when the company's consumers are switched off.
Oil cables are still used today, although their use has been reduced in recent years with the introduction of alternative cable types such as gas-insulated and polymer-insulated cables. Oil cables are generally used in situations where high power densities and long distances are required, such as long-distance and underwater power transmission.
In some countries, oil cables are also used for special applications such as in industry or for high-voltage direct current (HVDC) transmissions. However, more environmentally friendly alternatives are becoming increasingly popular, as the use of oil cables can be associated with high costs for maintenance, disposal and environmental pollution.
They are often replaced today for safety and environmental reasons. Oil cables consist of an insulated conduit filled with a liquid such as oil to improve insulation and aid the transmission of electrical current. Although oil cables are effective, they can leak if damaged or malfunction and pose a risk to the environment. If oil leaks into the environment, it can pollute soil and water bodies and have a negative impact on the environment and human health.
In addition, oil cables can require longer maintenance in the event of a power failure than other types of cables, as the oil leakage must be eliminated and the system refilled before it can be put back into operation. Modern cable types such as gas-insulated cables or polymer-insulated cables therefore offer a safer and more environmentally friendly alternative to oil cables.
In the solar industry, PAC stands for "Power Availability Factor". This value indicates the ratio between the actual available power of a solar system and the theoretically possible power that could be generated under optimal conditions. A high PAC value indicates that the solar system is working reliably and effectively and produces a high availability of electricity.
A parallel connection in photovoltaics refers to the way in which several solar modules are connected together in order to achieve a higher output. In a parallel connection, the positive connections of all solar modules are connected together and the negative connections of all solar modules are also connected together. This creates a common circuit with several parallel paths, which increases the total current of the circuit. This parallel connection keeps the voltage constant while increasing the current. This means that the total output of the circuit is proportional to the number of solar modules in the parallel circuit. A parallel connection is often used to increase the output of a solar system or to ensure that a failure or malfunction of one module does not affect the entire solar system.
Peak Shaving (Peak load smoothing is a concept used in the energy supply industry to reduce electricity consumption during periods of high demand. During these times, also known as peak load times, the demand for electricity usually rises sharply, which can lead to higher electricity requirements and higher electricity prices.
Peak shaving refers to reducing electricity demand by reducing peak load. This is achieved through the use of energy storage or other technologies that automatically reduce electricity consumption by storing energy at times of low demand and then releasing it at times of high demand.
By implementing peak shaving, energy supply companies can better manage demand during peak load times and thus achieve greater efficiency. At the same time, this can help to improve the stability of the electricity grid and reduce electricity costs for consumers.
The performance ratio (PR) is a key figure used in the photovoltaic industry to evaluate the efficiency of a solar system. It is the ratio between the energy actually generated by the system and the theoretical energy that can be generated under optimal conditions.
The formula for calculating the performance ratio is as follows:
PR = (energy actually generated) / (installed output x yield factor x module area)
The installed output refers to the nominal output of the system, the yield factor takes into account the specific climatic conditions and the module area refers to the total area of the installed solar modules.
A PR of 1.0 would mean that the system is operated under optimal conditions and generates the maximum theoretical energy. A PR of less than 1.0 would mean that the system is operating below its theoretical capabilities and improvements are required to increase efficiency.
Perovskite solar cells are a type of solar cell manufactured on the basis of perovskite materials. Perovskites are crystalline materials that have a structure similar to that of the natural mineral perovskite. These materials have special optoelectronic properties that make them promising candidates for solar cell technology.
Perovskite solar cells are able to achieve higher efficiencies than the best silicon solar cells. They are also comparatively easy and inexpensive to produce, which increases their potential for widespread use in solar energy. However, there are still some technological challenges that need to be overcome in order to improve their performance and stability.
The photoelectric effect is a fundamental physical phenomenon that plays an important role in photovoltaics (PV). The photoelectric effect refers to the fact that electrons can be released from a material by irradiating it with light.
In photovoltaics, this effect is used to convert solar energy into electrical energy. In the production of solar cells, materials are used that are capable of releasing electrons when they are struck by light. When sunlight hits the solar cell, some of the light's energy is absorbed by the electrons, causing them to be released from the material.
The solar cell is designed so that the released electrons flow in a certain direction and generate a current voltage. This current can then be used to generate electricity. The amount of electricity generated depends on various factors, such as the intensity of the light, the type of material used and the structure of the solar cell.
The photoelectric effect is therefore an essential component of photovoltaic technology and enables solar energy to be converted into electrical energy.
Photovoltaics refers to the technology used in solar systems to convert sunlight directly into electrical energy. Photovoltaic technology is based on the photoelectric effect, in which electrons can be extracted from a material by absorbing light.
A typical solar panel consists of an array of solar cells made from materials such as silicon that are capable of releasing electrons when hit by sunlight. The solar cells are connected together and mounted in a frame to protect them and collect the energy.
When sunlight hits the solar cells, the electrons released are directed in a specific direction, thereby generating an electric current. The electricity generated then flows through electrical cables and can be used to power electrical devices or to feed into the power grid.
The performance of the solar system depends on the intensity of the sunlight that hits the solar cells, as well as other factors such as the type of solar cells and the size of the system. Photovoltaic systems are often used to power buildings, streetlights, traffic signals and other applications where an independent and environmentally friendly energy supply is required.
There are several photovoltaic subsidy programs in Germany that are specifically aimed at trade and industry. Some of the most important funding opportunities are listed here:
KfW promotional program "Renewable Energies - Standard" (program number 270/271): This program offers low-interest loans and repayment grants for investments in renewable energies such as photovoltaic systems. It is aimed at companies and self-employed persons based in Germany who wish to install photovoltaic systems with an output of up to 10 MWp.
Federal funding for energy efficiency in the economy (program number 2020-11): This program supports investments in energy efficiency measures, including the installation of photovoltaic systems. It is aimed at small and medium-sized companies based in Germany.
EEG levy exemption: Companies that use self-generated electricity from renewable energy sources such as photovoltaic systems can be exempt from the EEG levy (a tax to promote renewable energy) under certain circumstances. However, the requirements and conditions for the EEG levy exemption are complex and should be checked by an expert.
Subsidy programs of the federal states: Some federal states offer their own subsidy programs for photovoltaic systems, which are aimed at companies and tradespeople. The conditions and funding amounts vary depending on the federal state.
It is advisable to seek advice from an expert when looking for funding opportunities for photovoltaic systems to ensure that all available options are considered.
A photovoltaic module is an electronic component that converts sunlight into electrical energy. It is the basic component of a photovoltaic system and consists of an array of solar cells mounted in a frame and covered with a glass or plastic surface.
A typical solar cell is made of a semiconductor material such as silicon, which is capable of releasing electrons when hit by sunlight. The solar cells in a photovoltaic module are interconnected and connected in series to generate a higher voltage that can be used to power electrical devices or feed into the grid.
A photovoltaic module is usually rectangular or square in shape and can be available in different sizes and power classes. The output of a module is given in watts (W) and depends on the size and number of solar cells. Typically, photovoltaic modules have outputs of 100 to 400 Wp (watt peak).
Photovoltaic modules can be used in a variety of applications, from small solar chargers to large solar power plants. They are often used to power buildings, streetlights, traffic signals and other applications where an independent and environmentally friendly energy supply is required.
In Germany, there is no general Photovoltaic obligation for building owners or developers. However, there are some federal states and municipalities that require or promote photovoltaic systems on certain buildings. For example, since 2020, the state of Baden-Württemberg has issued a regulation stating that at least 15 percent of the roof area of new non-residential buildings with a usable area of more than 1,000 m² must be used to generate electricity from renewable energy sources. Other federal states have introduced similar regulations or are planning to do so in the future. However, there are various subsidy programs that can provide companies with financial support for the installation of photovoltaic systems. In addition, some federal states have set up their own subsidy programs for companies wishing to invest in photovoltaic systems. For example, the state of North Rhine-Westphalia has set up the "Photovoltaics on open spaces" funding program, which supports companies in setting up photovoltaic systems on open spaces.
Polycrystalline solar cells are a type of solar cell used in photovoltaic technology. In contrast to monocrystalline solar cells, polycrystalline solar cells consist of several crystallites that are aligned differently and therefore have an irregular structure.
The production of polycrystalline solar cells is simpler and less complex than monocrystalline solar cells, which means that they are generally more cost-effective. However, they also have a lower efficiency than monocrystalline solar cells and are generally less efficient.
Polycrystalline solar cells have a bluish color and are generally somewhat smaller than monocrystalline solar cells. However, they are able to generate electricity even with less sunlight and are therefore also suitable for locations with slightly poorer light conditions.
Overall, polycrystalline solar cells are a cost-effective and practical choice for generating solar power.
A Power Purchase Agreement (PPA) is a contract between a power producer and a power purchaser under which the power producer supplies power to the purchaser at an agreed price and for a specified period of time. PPAs are often used by companies, government agencies or other organizations to meet their renewable energy needs and reduce their energy costs.
The electricity can come from different energy sources, such as solar energy, wind energy or hydropower. By concluding a PPA, the electricity consumer can ensure that it receives a reliable supply of electricity at a predictable price, while the electricity producer has a long-term buyer for its electricity and can thus secure the financing of new power plants or renewable energy projects.
More about PPA in our report.
A photovoltaic module is a unit consisting of several interconnected solar cells that are capable of converting sunlight into electrical energy. Most photovoltaic modules consist of 60 or 72 solar cells and measure around 1.6 x 1 meter. They are usually installed on the roofs of buildings, in open spaces or in other suitable locations to generate solar power.
The solar cells in a photovoltaic module are made of silicon, a semiconductor material that is able to generate electrons when it is hit by sunlight. Each solar cell consists of a layer of n-doped silicon and a layer of p-doped silicon separated by a boundary layer. When sunlight hits the solar cell, electrons are released from the boundary layer and driven through an electric field in the solar cell. This generates a direct current, which is usually converted into alternating current to be used as a power supply.
A photovoltaic module usually consists of an enclosure made of an aluminum frame and glass or other transparent materials. This frame protects the solar cells from the weather and ensures that the sunlight can reach the solar cells unhindered. There is a connection box on the back of the photovoltaic module that enables the connection between the module and the inverter. The inverter converts the direct current into alternating current, which is used for electricity consumption in the building or for feeding into the public grid.
Photovoltaic modules are an important component of solar systems and make it possible to generate clean, renewable energy from sunlight.
A pyranometer is a measuring instrument for determining the global horizontal radiation on a surface that is aligned perpendicular to the solar radiation. It therefore measures the solar radiation on a horizontal surface, regardless of the direction from which the light is coming.
A pyranometer consists of a flat disk covered with a sensitive solar cell that converts the incident sunlight into electricity. The solar cell is usually surrounded by a glass body that protects the solar cell from environmental influences. The instrument is designed to provide an accurate measurement of solar radiation by measuring the entire visible and infrared light spectrum.
Pyranometers are often used in the photovoltaic industry and in solar power plant planning to measure the available solar energy at different locations. The measurements can be used to estimate the output of solar installations and also to determine hours of sunshine or to monitor weather conditions.
In summary, a pyranometer is a measuring instrument that measures solar radiation on a horizontal surface and is used to assess solar radiation at various locations in the photovoltaic industry and in solar power plant planning.
Redispatch for PV systems refers to the adjustment of electricity production from photovoltaic systems (PV systems) due to grid bottlenecks or grid overloads. If the electricity grid is overloaded or a bottleneck occurs, the grid operator can request the operator of PV systems to reduce or increase electricity production in order to balance the power supply in the grid and ensure grid stability.
This adjustment of electricity production is known as "redispatch" and there may be financial compensation for the PV system operator who carries out this adjustment. Redispatch is an important part of the electricity market design to ensure that the electricity supply is maintained and that renewable energies, such as PV systems, can make their contribution to grid stability.
Further information can be found in our Article.
Reflected radiation in photovoltaics refers to the part of the incident solar radiation that is not absorbed by the solar cell but is reflected by the surface of the photovoltaic module. Reflection occurs when the sunlight hits the surface of the module and is reflected back without penetrating the solar cells.
The reflection of sunlight on the surface of a photovoltaic module is an important factor that can influence the efficiency of photovoltaic systems. If too much sunlight is reflected, some of the energy that could otherwise be used to generate electricity is lost. This can lead to a reduction in the output of the photovoltaic system.
In order to reduce the reflection of sunlight, special coatings are usually applied to the surface of the photovoltaic modules. These coatings are formulated to better absorb and reflect sunlight, resulting in higher efficiencies of the photovoltaic modules. In addition, other technologies such as anti-reflective coatings can also be used to minimize reflected radiation and thus increase the energy yield of photovoltaic systems.
In summary, reflected radiation in photovoltaics refers to the part of the incident solar radiation that is reflected by the surface of the photovoltaic module. In order to increase the efficiency of photovoltaic systems, special coatings are applied to the surface of the modules to reduce the reflection of sunlight.
Reflection losses in photovoltaics occur when part of the incident solar radiation is reflected on the surface of the photovoltaic module and therefore cannot be absorbed by the solar cells. These losses can reduce the efficiency of photovoltaic systems as they lead to less electricity being generated.
The reflection losses depend on various factors, such as the type of surface of the photovoltaic module, the angle of the solar radiation and the wavelength of the light. A smooth and shiny surface, for example, tends to have higher reflection losses than a matt or rougher surface. The angle of the solar radiation can also play a role, as more light is reflected at flat angles than at steeper angles.
Various measures can be taken to minimize reflection losses. One possibility is the use of special coatings on the surface of the photovoltaic modules, which absorb sunlight better and thus reduce reflection losses. Another possibility is the use of anti-reflective coatings, which can reduce the reflected light and thus increase the amount of solar energy absorbed by the solar cells.
To summarize, reflection losses in photovoltaics occur when part of the incident solar radiation is reflected on the surface of the photovoltaic module and cannot be absorbed by the solar cells. To minimize the losses, special coatings or anti-reflective coatings can be used on the surface of the modules.
Control energy is energy that is used at short notice to compensate for fluctuations in the electricity grid and keep the grid frequency stable at 50 Hertz. If electricity supply and demand do not match exactly, balancing energy intervenes to compensate for shortfalls or surpluses in the grid and thus prevent outages. There are different types of balancing energy, depending on the reaction time and duration: primary, secondary and minute reserve. Operators of battery storage systems can use balancing energy to generate additional income. You can read how this works in our report Control energy: additional income through electricity storage.
Series connection is a method of connecting photovoltaic modules. Several solar cells are connected in series to generate a higher voltage. In series connection, the positive electrodes of the solar cells are connected to the negative electrodes of the next cell. In this way, the individual voltages of the solar cells add up to a total voltage.
In the series connection, the same current flows through each solar cell, while the voltages of the cells add up. For example, if three solar cells with a nominal voltage of 0.5 volts are connected in series, the total voltage is 1.5 volts (0.5 V + 0.5 V + 0.5 V).
Series connection can be used to increase the output voltage of photovoltaic modules and generate higher voltages that are suitable for operating electrical devices or charging batteries. However, it is important that all solar cells deliver the same current when connected in series, otherwise the weakest cell will limit the current and thus reduce the overall output. Therefore, the solar cells within a module must be carefully selected and matched to ensure optimum performance.
In summary, series connection is a method of connecting photovoltaic modules by connecting several solar cells in series to generate a higher voltage. Series connection increases the output voltage of the modules, but requires careful selection and matching of the solar cells to ensure optimum performance.
The return on investment in photovoltaics refers to the ratio between the expected profits and the investment costs in a solar system. The return is usually expressed as a percentage and indicates what percentage of the investment costs will be recouped through electricity generation over a certain period of time.
The return on investment for photovoltaics depends on various factors, such as the size of the solar system, the orientation and inclination of the roof, the location of the system, the price of the electricity that is fed into the grid and the operating and maintenance costs of the system. A higher return is usually achieved through higher electricity generation and lower operating costs.
The return on investment for photovoltaics is usually calculated over the service life of the solar system, which can be between 20 and 30 years depending on the system and manufacturer. An example: If a solar system with investment costs of 50,000 euros generates a profit of 10,000 euros per year, the return is 20 percent.
The return on investment for photovoltaics is generally higher than for other investments, as energy costs are expected to rise in the future and investing in a solar system can help to reduce energy costs or create an additional source of income. However, returns on photovoltaics can vary depending on location and other factors, so careful planning and analysis of costs and returns is necessary before making an investment.
Repowering of PV systems refers to the replacement or modernization of obsolete or inefficient photovoltaic modules in order to increase energy production and improve performance.
This can be achieved by replacing old modules with more modern, efficient modules that enable higher energy production. In addition, repowering can also include the installation of more advanced mounting systems, inverters and other components that can further improve the efficiency of the plant.
Repowering can make sense for PV systems when older modules lose their performance due to ageing or damage or when more modern technologies become available that enable higher energy production. Repowering can extend the service life of the PV system and at the same time improve energy production and profitability.
Residual load is a term used in the energy sector, particularly in the context of electricity supply. It refers to the difference between the actual demand for electricity (consumption) and the available electricity generation at a specific point in time. More detailed information on Residual load in our article.
An RLM meter, also known as a recording load meter, is an electronic energy meter that is able to record energy consumption in real time. "RLM" stands for "recording load profile measurement". In contrast to conventional Ferraris meters, which only record total consumption over a certain period of time, RLM meters enable more detailed recording of energy consumption. They record data such as instantaneous power consumption, voltage, current and time, thus providing a more accurate analysis of energy consumption. RLM meters are often used in commercial and industrial environments where accurate tracking of energy consumption is important, for example for billing purposes or to optimize energy efficiency.
W - Z
A wafer in PV systems (photovoltaic systems) is a thin slice of crystalline silicon that serves as the basis for the production of solar cells. The wafers are cut from silicon blocks, which are produced from the raw material silicon. They typically have a thickness of around 200 micrometers (0.2 mm) and a diameter of 15 to 20 cm.
The wafers are usually cleaned and etched using special processes to improve the surface structure and then treated with dopants such as boron or phosphorus to achieve certain electrical properties. They are then converted into solar cells by covering them with layers of materials such as silicon dioxide, aluminum oxide and silicon nitride and fitting them with special conductors and contacts to generate electricity from solar energy. The solar cells are finally assembled into PV modules or PV panels to produce electrical energy from sunlight.
Detailed information on Wafers in photovoltaics in our article.
A wallbox, also known as an electric vehicle charging station, is a stationary charging station for electric cars and plug-in hybrid vehicles that is typically mounted on a wall or pole. A wallbox is used to supply electric vehicles with electricity to charge their batteries.
Wallboxes are designed to deliver power safely and quickly to reduce the charging time for electric vehicles. They are equipped with an integrated electricity meter to record power consumption and charging costs, and can often be controlled via a mobile app or web portal to start, stop or program the charging process.
Wallboxes are available in various power levels, ranging from 3.7 kW to 22 kW.
A converter in a PV system (photovoltaic system) is an electronic device that converts the direct current (DC) from the solar cells into alternating current (AC) in order to feed the generated energy into the power grid or supply it directly to a consumer.
Solar system maintenance intervals and procedures may vary depending on the type and size of the system as well as the operating conditions and environmental factors, such as climate, location, degree of soiling and age. In general, however, it is recommended that solar systems should be inspected and maintained regularly, usually once a year, by a professional solar specialist or installer.
Here are some of the most important maintenance tasks that should be carried out on a solar system:
Visual inspection: Visually inspect all parts of the system, including the modules, cabling and inverter, for visible damage such as cracks, holes, corrosion or loose connections.
Cleaning: Clean the solar panels regularly to maximize the performance of the system. Depending on the location and environment, cleaning may be necessary once a year or more often.
Check the power: Measure the actual power of the system with a power meter to ensure that it corresponds to the expected values.
Check the cabling: Check all connections and cables for damage, wear and corrosion and replace them if necessary.
Check the inverter: Check the inverter for error codes or alarms that could indicate problems and replace it if necessary.
Battery maintenance (if available): If your solar system has a battery bank, check the charge level, the condition of the batteries and replace them if necessary.
It is important to note that proper maintenance of the solar system not only improves the performance and lifespan of the system, but also ensures safety and minimizes potential damage or malfunctions.
Find out more in our article Maintenance of PV systems.
Watt peak (Wp for short) is a unit of measurement for the rated power of photovoltaic systems. The rated power refers to the maximum possible power that a solar cell or photovoltaic system can generate under standard test conditions (STC). The STC include a radiation intensity of 1000 W/m², a cell temperature of 25°C and an air mass of 1.5.
An inverter is an electronic device that converts the direct current (DC) from a power source into alternating current (AC). Inverters are used in many applications, including photovoltaic (PV) systems, to convert the direct current generated by the solar cells into grid-compliant alternating current suitable for connection to the public grid or for direct consumption in the company. Read more in our article The dimensioning factor for inverters.
Alternating current (AC) is a form of electrical energy that periodically changes its direction and strength. In contrast to direct current (DC), which always flows in the same direction, the direction of alternating current changes at regular intervals. The most common form of alternating current has a sine wave form in which the current passes through a positive and negative range.
Alternating current is used in most households and in industry to supply electricity, as it can be transported efficiently over long distances. Most power grids in the world work with alternating current. Alternating current is also used in many electronic devices that require alternating current to function, such as electric motors and air conditioning systems.
The wind load on PV systems refers to the force exerted by the wind on the system components, such as solar modules, mounting systems and cabling. This force depends on the wind speed and the orientation of the system and can cause the system to move or be damaged.
The calculation of the wind load is an important factor in the planning and installation of PV systems, as it must ensure that the system can withstand the loads. The required stability can be achieved through suitable anchoring, design of the mounting systems and fastening elements.
In addition to the wind load, other loads, such as snow loads, must also be taken into account to ensure that the PV system can be operated safely and reliably.
Active power limitation for PV systems refers to the limitation of the maximum active power that can be generated by the system. This limitation may be necessary if the grid infrastructure has a certain capacity or if the grid stability is impaired by the feed-in of too much electricity.
Active power limitation is normally realized by a power limiter, also known as a "power limiter". This can be implemented in the form of electronic components such as thyristors or transistors, which can limit the power of the system as required.
Another reason for limiting the active power may be to be able to take advantage of the feed-in tariff. In some countries, grid operators can offer certain feed-in tariffs if the system does not exceed a maximum output limit.
Active power limitation is an important issue in the PV industry, as it ensures that PV systems can be operated safely and reliably and that the power grid is not impaired.
The efficiency of PV systems refers to the ratio between the electrical power generated by the system and the amount of solar energy that reaches the system. The efficiency is usually given as a percentage and indicates how efficiently the system can convert solar energy into electrical energy.
There are various factors that influence the efficiency of a PV system, such as the quality of the solar modules, the orientation of the system, the intensity of the solar radiation and the temperature. The higher the efficiency, the more electricity can be generated by the system and the more profitable the system becomes.
Most commercial PV modules have efficiencies between 15% and 20%, while newer, more advanced modules can achieve efficiencies of up to 25%. Improving the efficiency of PV modules is an important area of research as it can help reduce the cost of solar energy and improve the profitability of PV systems.
Further information is available here.
Solar modules usually consist of several layers of materials that fulfill different functions in order to convert sunlight into electrical energy. There are two main types of solar modules: crystalline silicon modules and thin-film modules.
An overview of efficiencies and solar cell types can be found in our Contribution.
The cell efficiency (also known as solar cell efficiency) indicates how effectively a solar cell can convert incoming sunlight into electrical energy. It is given as a percentage and is based on the ratio of the electrical power generated to the incoming solar energy.
The efficiency of solar modules depends on many factors, such as the type of materials used, the design of the cell and the conditions under which the cell is operated. The best crystalline silicon solar cells can achieve an efficiency of over 25%, while the best thin-film solar cells can achieve an efficiency of up to 22%. In practice, however, the average efficiency of solar modules is usually between 15% and 20%.
ZEREZ is the central register for unit and component certificates in Germany. It is used to collect, store and provide evidence of the electrical properties of generation units and components. From February 1, 2025, the use of ZEREZ will be legally mandatory for manufacturers, system operators and grid operators in order to enable grid connection. Find out more in our article Certificate register ZEREZ.
A bidirectional meter, also known as a bi-directional meter, is an electronic measuring device that can measure the electricity consumption of a commercial operation both when energy is drawn and when it is fed into the electricity grid. In contrast to a conventional single-direction meter, which only measures the customer's electricity consumption, a bidirectional meter can also measure and record the flow of electricity in the other direction when the customer feeds self-generated energy from renewable sources such as solar or wind power into the grid.
C - D
CBAM stands for Carbon Border Adjustment Mechanism. It is a political measure of the European Union (EU) that aims to ensure that imported products manufactured in countries that have less stringent environmental standards than the EU bear a similar carbon price to products manufactured in the EU.
The CBAM is intended to prevent EU companies from being disadvantaged in international competition by being subject to stricter environmental regulations, while foreign products do not have to meet the same standards. The CBAM is therefore intended to create incentives to reduce greenhouse gas emissions and at the same time ensure fair competition on the global market.
The exact details and implementation of the CBAM may vary depending on EU policy decisions, but in general it aims to provide for the introduction of a carbon price on imported goods to ensure that they meet the same standards as products manufactured in the EU.
Find out more in our report on the CBAM.
The EEG Clearing House is a neutral institution for resolving disputes and application issues relating to the EEG and is operated on behalf of the Federal Ministry for Economic Affairs and Climate Protection. It is the energy industry's central point of contact for all matters relating to the EEG and settles disputes between PV system operators, grid operators, direct brokers or metering point operators.
The carbon footprint refers to the amount of carbon dioxide (CO₂) emitted by a company, product, process or event during its entire life cycle. The balance includes both the direct and indirect emissions of CO₂ and other greenhouse gases caused by the activity.
The carbon footprint is often used as a measure of the environmental impact of activities, as the emission of greenhouse gases such as CO₂ contributes to climate change. A positive carbon footprint means that more CO₂ is emitted than can be absorbed or offset, resulting in a net increase in greenhouse gas emissions and therefore global warming. A negative CO₂ balance, on the other hand, means that more CO₂ is absorbed or offset than is emitted, which contributes to a reduction in greenhouse gas emissions.
It is important to monitor and reduce the carbon footprint in order to minimize the impact of activities on the environment and combat climate change. Companies and governments can take various measures to improve their carbon footprint, such as using renewable energy, improving energy efficiency and switching to greener technologies and processes.
CO₂ certificates are trading instruments that are used to limit and reduce greenhouse gas emissions, in particular carbon dioxide (CO₂). They are also known as emission certificates or climate certificates.
CO₂ certificates are part of emissions trading systems set up by governments and international organizations to regulate and reduce greenhouse gas emissions. Companies that cause greenhouse gas emissions must purchase CO₂ certificates in order to maintain or reduce their emissions to a certain level. One certificate entitles the holder to cause one ton of CO₂ emissions.
The aim of emissions trading is to create incentives for companies to reduce their emissions by limiting their emissions and selling surplus certificates to other companies that are unable or unwilling to limit their emissions. This creates a financial motivation for companies to reduce their emissions by either improving their production processes or investing in renewable energy sources.
CO₂ certificates are also used by governments to finance climate protection projects. Companies can buy certificates generated by climate protection projects to offset or compensate for their emissions.
The Corporate Sustainability Due Diligence Directive (CSDDD) is an EU proposal to oblige companies to fulfill human rights and environmental due diligence obligations along their supply chains. The aim is to ensure that companies identify, prevent, mitigate and report on potential negative impacts of their business activities on human rights and the environment.
Find out more in our report on the CSDDD.
CSRD is the Corporate Sustainability Reporting Directive, which obliges companies to report.
More on the topic CSRD.
With PV contracting a third party invests and the client bears no economic risk. The client saves up to 30% in electricity costs, without any financial or personnel costs of their own. Fully financed by an investor, the PV system produces low-cost solar power on a roof or open space and the company becomes more climate-neutral - with a system that is perfectly tailored to individual electricity consumption. It is the easiest way to achieve a low-cost electricity supply, while the client simply continues to concentrate on its core business.
As a general rule, PV modules should ideally face south in order to achieve the highest energy yield. The so-called azimuth angle is 0°. In Germany, an orientation between south-east and south-west at an azimuth angle of 45° or -45° is still considered sensible and the optimum tilt angle is around 30°. However, other solutions also make sense in relation to the roof area and yield. Orientation to the east and west on a flat roof has the advantage that the modules do not shade themselves in any season and therefore more modules can be installed on the same area. However, it is important to note that other factors such as the degree of shading and the ambient temperature can also have an influence on energy generation. CUBE CONCEPTS plans and installs all PV systems taking into account the specific conditions on site so that maximum yields are always guaranteed.
With a roof penetration, the solar modules or the mounting systems of the solar modules are connected or screwed directly to the roof so that the roof cladding is damaged and then has to be sealed again. The PV roof systems installed by CUBE CONCEPTS generally do not require roof penetration.
The net roof area is decisive for the calculation of a PV system. This is the roof area without overlaps. When a roof is covered with solar modules, the areas for skylights, skylight domes, lightning conductors, ventilation shafts or smoke and heat protection systems are also deducted.
You can find out whether your roof is suitable for a PV system in our Whitepaper.
Roof hooks are special fastening devices that are only used when mounting solar modules on tiled roofs. They connect the roof to the solar modules directly or to the mounting systems.
Roof integration of photovoltaic systems refers to the installation of solar cells into the roof structure of a building. Instead of installing separate solar cells on a roof or on a free-standing frame, the solar cells are integrated directly into the roof cladding to create a more aesthetic and seamless solution.
The integration of solar cells into the roof requires careful planning and cooperation between the building owner, the roofer and the solar specialist. The solar cells can be integrated into various roof materials such as roof tiles, slate, metal or bitumen. However, this requires a special design of the roof construction and the integration of inverters that convert the direct current generated by the solar cells into alternating current that can be fed into the building's electricity grid.
The roof pitch indicates the angle of inclination of a roof surface. The optimum angle of inclination of a roof in Germany is approx. 30° in order to be able to install an effective photovoltaic system directly on a roof. The roof should face due south. As this is rarely the case, mounting systems for PV systems are used so that the solar modules can be perfectly aligned. A roof pitch of at least 10° has the advantage that solar modules are self-cleaning due to rain and snow.
The DC rated power refers to the maximum power that can be generated by the solar modules in a photovoltaic (PV) system under standard test conditions. This rated power is usually expressed in watts (W) or kilowatts (kW).
The DC rated power indicates how much energy the solar cells can deliver under optimum conditions without any losses due to other components such as inverters or cabling. Standard test conditions normally include an irradiance of 1000 watts per square meter, a cell temperature of 25 degrees Celsius and an air mass factor of 1.5.
As the DC rated power depends on the specific design of the solar modules, it is usually specified by the manufacturer and is indicated on each solar module. The DC rated power is an important factor when selecting solar modules, as it influences how much energy a PV system can generate. A higher DC rated power value means that the module can generate more energy under the same conditions than a module with a lower rated power.
However, it should be noted that the actual performance of PV systems depends on many factors, including climatic conditions, the orientation and tilt of the solar module, cleaning and maintenance of the system, and the quality of the components used. Therefore, the DC rated power is normally used as a reference value and is not necessarily a guarantee of the actual performance of the PV system.
A data logger is an electronic device used in photovoltaic (PV) systems to monitor and record data. It collects information about the performance and operation of the PV system and stores it in a digital file or cloud platform.
The data logger is usually connected to the PV system's inverters to collect data such as current and voltage values, yield data, weather conditions and other operating parameters. Some data loggers can also be connected to sensors to measure environmental conditions such as temperature, wind speed and irradiation.
The collected data is used to monitor the PV system and optimize energy production. By analyzing the data, the owner or operator of the PV system can evaluate the performance of the system and identify deviations from the expected values that may indicate a potential problem. The data logger can also be used to troubleshoot and maintain the system.
Some data loggers can be connected wirelessly or via an Ethernet connection to a computer or mobile device to enable real-time monitoring and reporting on PV system performance. Other data loggers have local storage or send data directly to a cloud platform where it can be accessed from any device with an internet connection.
Overall, the data logger is an important tool for monitoring and analyzing PV systems to ensure that they operate efficiently and reliably and achieve the highest possible yield.
DC (Direct Current) is a type of electrical current in which the current flows in only one direction. This means that the electric current always flows in the same direction, in contrast to alternating current (AC), where the direction of the current is constantly changing.
Direct current is often used in batteries, solar cells and electronic devices that require direct current to function. For example, the current generated by a solar cell is called direct current because it only flows in one direction. Direct current is also used in vehicles with electric motors, particularly hybrid and electric vehicles.
As a rule, devices and systems that use direct current must also be a direct current source, such as a battery or a power supply unit, to provide the current. Direct current can also be generated by converting alternating current, for example by using an inverter that converts the alternating current into direct current.
Compared to alternating current, direct current is considered easier to control and regulate and can also be transmitted more efficiently over longer distances. However, there are also disadvantages of direct current, for example its lower effectiveness in transmitting large amounts of power over long distances, which is why it is usually used for local and decentralized power supply systems or in electronic devices.
Degradation refers to the slowly decreasing efficiency of solar modules. Modern monocrystalline solar modules with the highest efficiency currently available have a long service life. At present, for example, the guaranteed remaining output after 20 years is 90%.
Degression refers to the annual reduction in the EEG feed-in tariff for photovoltaic systems. It is calculated from a fixed basic regression and a variable percentage, which is based on the increasing overall share of PV electricity in Germany and therefore varies from year to year. Since the amendment to the EEG for 2023, the different feed-in tariff levels vary for system outputs from 100 kWP to 1 MWP. The remuneration rates for direct marketing under the EEG have been increased for new solar installations smaller than 1 MWP. However, photovoltaic systems with a nominal output of more than 1 MWP are subject to tendering. Here, the remuneration rates are not fixed, but are determined via a tendering system.
Depot charging refers to a charging strategy in which electric vehicles are charged at a central depot. This method is particularly suitable for fleet operators who operate vehicles according to fixed routes. The advantages are the efficient use of the charging infrastructure and the ability to charge cheaply overnight. As environmental regulations become stricter and electric commercial vehicles are more economical in the long term, this strategy is becoming increasingly important. Requirements for depot charging include an efficient charging infrastructure, intelligent charging systems and a sufficiently dimensioned grid connection.
Find out more in our article: Depot charging - e-mobility for commercial vehicles
The DGVU is the "German Social Accident Insurance" and V3 refers to "Regulation 3". This accident prevention regulation governs the handling of electrical systems and equipment. One of the principles is: The employer must ensure that electrical systems and equipment are only installed, modified and maintained by a qualified electrician or under the direction and supervision of a qualified electrician in accordance with the electrotechnical regulations. Regular testing is prescribed here for PV systems.
Diffuse radiation refers to the light that is scattered by the sun in all directions and does not hit the surface of a solar module directly. In contrast, direct radiation refers to the light that falls directly on the surface of the solar module.
Diffuse radiation is caused by the influence of clouds, haze and air pollution, which scatter the sunlight and thus produce a more even, softer light. It is also present when the sunlight is reflected from the surface, as is the case with snow, water or light-colored surfaces, for example.
The efficiency of PV systems depends on the amount of direct and diffuse radiation they receive. While solar modules respond most effectively to direct radiation, diffuse radiation can still contribute to electricity generation.
Modern solar modules are designed in such a way that they can achieve a higher energy yield from diffuse radiation. These modules are designed to capture sunlight from all angles and achieve a higher energy yield, even in weak or scattered light. The ability of a solar module to absorb diffuse radiation is referred to as diffuse radiation sensitivity and is an important factor in evaluating the performance of solar modules.
DIN EN 16247 defines standards for independent energy audits that help companies to improve their energy efficiency and reduce costs. It was first introduced as a mandatory requirement for non-SMEs in 2015 as part of the EDL-G and must be repeated every four years. Companies with more than 250 employees, an annual turnover of more than €50 million and a balance sheet total of more than €43 million are affected. The audits serve to analyze energy consumption, identify potential savings and improve energy-related processes. SMEs can carry out voluntary energy audits in order to benefit from tax relief and cost savings. The standard sets out the procedure and standards for carrying out the audits, including the assessment of the cost-effectiveness of proposed measures. Companies must report the results to BAFA and implement the proposed measures if the net present value is positive. Energy audits are an important instrument for increasing operational energy efficiency and are increasingly being used in legislation.
More on the topic DIN EN 16247 in our article.
DIN EN 17463, also known as VALERI, is a standard for the evaluation of energy-related investments that was developed by the European Union and various banks. It serves as a standardized tool for calculating the profitability of energy efficiency measures and is embedded in various pieces of legislation, such as the Energy Financing Act and the EU ETS electricity price compensation. The standard is relevant for companies with a total annual energy consumption of more than 10 GWh and for those that have introduced energy management or environmental management systems. It defines standards for collecting and calculating information and for evaluating investments in order to support decisions on energy efficiency measures. Energy officers, energy management teams, energy consultants and auditors use the standard to evaluate the cost-effectiveness of investments and justify decisions. The standard is also used to meet legal requirements such as the EnSimiMaV, which obliges companies to implement energy-saving measures if the net present value is positive after 20 % of the term.
More about the DIN EN 17463 in our report.
Direct marketing of solar electricity refers to the process whereby operators of photovoltaic systems sell the electricity they generate directly to end customers or on the electricity exchange instead of selling it to the grid operator at a fixed tariff.
Direct marketing enables operators of solar installations to increase their income by achieving higher prices for their electricity than they would receive if they fed it into the public grid. However, it also requires a certain amount of expertise and resources to market the electricity effectively and achieve the right price.
Direct marketing can be carried out using various models. One model is the sale of electricity to end customers, for example to companies that want to obtain their energy requirements from renewable sources. Another model is to sell to electricity traders or on the electricity exchange. In some countries, there are also special direct marketing platforms that make it easier for solar plant operators to sell their electricity.
The direct marketing of solar power can also help to improve the integration of renewable energy into the electricity grid, as it helps grid operators to forecast and control the feed-in of electricity into the grid. By marketing solar power, operators of solar installations can also help drive the energy transition and support the transition to a more sustainable energy supply.
Third-party volume deferral applies to companies that claim certain advantages in the energy sector, whether by producing energy themselves or by passing on electricity to third parties or end consumers. These companies must carry out a third-party volume deferral if they wish to continue to benefit from reduced taxes, levies, surcharges or favorable grid usage. These benefits only apply to the main consumer within their premises. As soon as the electricity they purchase or generate themselves is passed on to one or more end consumers, they are classified as electricity supply companies in accordance with the Renewable Energy Sources Act (EEG).
Find out more in our Blog article.
In the energy industry, a dark doldrums describes a weather situation in which there is little wind and little sunshine, which means that wind and solar systems hardly produce any electricity. This poses a challenge for energy systems that rely heavily on renewable energies. Energy storage solutions, backup systems such as gas or coal-fired power plants, flexible grid management measures and the import of electricity from other regions are used to cope with dark doldrums. We have published a detailed report on how to deal with a Dark doldrums and solutions.
A thin-film module is a type of solar module that is made from a thin layer of photovoltaic material applied to a substrate. In contrast, conventional solar modules are made of crystalline silicon, which is cast in thick slices and built up in several layers.
Thin-film technology uses materials such as amorphous silicon (a-Si), cadmium telluride (CdTe), copper indium gallium selenide (CIGS) or organic materials to create a thin layer, which is then applied to a substrate. Compared to conventional solar modules, thin-film modules have the advantage that they can be manufactured more cost-effectively, as less material is required and production is less expensive. Thin-film modules can also be more efficient in low light and at high temperatures.
However, thin-film modules generally also have a lower efficiency compared to crystalline solar modules. They are therefore often used in larger quantities in order to achieve a comparable energy yield. They are also often more flexible and lighter than conventional solar modules, which makes them suitable for use in certain applications such as mobile systems, roof integration and façades.
K - L
The calculation of the cable thickness for photovoltaic systems depends on several factors, including the maximum current that will flow through the cables, the cable length and the cross-section of the cable.
One way to calculate the cable thickness is to use the formula:
Cable strength = (maximum current x cable length x 2) / (cable cross-section x current-carrying capacity factor)
The maximum current depends on the size of the photovoltaic system and the inverter output. The cable length refers to the distance between the solar modules and the inverter. The cable cross-section and the current carrying capacity factor depend on the respective cable type.
It is important to calculate the cable thickness correctly to ensure that the cables can safely transport the current flowing through the system. If the cable thickness is too low, this can lead to a loss of power and a safety risk. It is therefore advisable to have the cable thickness calculated by an experienced electrician or a specialist in photovoltaic systems.
Cable losses occur due to the electrical resistance in a cable. When current flows through a cable, it does not flow through the material of the cable without resistance, but there is an electrical resistance that gives off energy in the form of heat. This energy is referred to as cable losses, as it leads to a loss of electrical energy.
The amount of cable loss depends on several factors, such as the length of the cable, the cross-section of the cable, the current flowing through the cable and the material of the cable. As a rule, the longer the cable, the higher the cable losses. The higher the current, the higher the cable losses. To minimize cable losses, you can use a cable with a larger cross-section, which reduces the electrical resistance.
Cable losses can play a role in the installation of PV systems, as they can lead to a loss of energy before the electricity is transported from the solar module to the inverter. It is important that cable losses are taken into account when planning and installing a photovoltaic system to ensure that the system functions optimally and energy efficiency is maximized.
A Capacity market is a mechanism in the energy market that ensures that sufficient electricity capacity is available at all times to meet demand. Operators of power plants or other energy sources receive payments not only for the energy actually supplied, but also for the fact that they can provide capacity and produce electricity when needed. The aim is to ensure security of supply and avoid blackouts by maintaining sufficient reserves.
A characteristic curve measurement is a type of test that is carried out on photovoltaic systems to collect information about the behavior of the system under different conditions. In a characteristic curve measurement, the current-voltage characteristic curve (I-V characteristic curve) of the solar module is recorded by measuring the current and voltage under different conditions.
Typically, a characteristic curve measurement is performed to obtain information about the performance of a solar module in different operating conditions. For example, a characteristic curve measurement can be performed to collect information on how the performance of a solar module depends on the intensity of sunlight, temperature or load.
A typical characteristic measurement can be carried out under standard test conditions (STC), where the module temperature is 25°C and the illuminance is 1000 W/m². However, such a measurement can also be carried out under actual operating conditions to determine the actual performance of the module.
The results of a characteristic curve measurement can be useful in the planning, installation and maintenance of photovoltaic systems, as they provide important information about the behavior of solar modules under different conditions.
Conversion areas are areas on which solar parks or ground-mounted photovoltaic systems can be installed in accordance with the EEG. This has also been possible on so-called disadvantaged areas since the 2017 law reform. This refers to areas in commercial and industrial zones as well as the extensive verges of freeways and railroad lines. This applies to operational storage and expansion areas or compensation areas of companies. However, disused landfills, gravel pits, quarries, sports facilities, former military areas or marshland and large areas of water are also conceivable.
A crystalline solar cell is a type of solar cell used in photovoltaics to convert solar energy into electrical energy. The crystalline solar cell is currently one of the most common types of solar cell on the market.
A crystalline solar cell consists of a semiconductor material, which is usually silicon. The silicon is formed into a wafer shape in a specific process and then cut into thin slices that serve as solar cells. The cell consists of several layers, usually of p-doped and n-doped silicon, to form a pn junction that enables charge separation.
Crystalline solar cells can be divided into two types: monocrystalline and polycrystalline. Monocrystalline solar cells consist of a single crystal, while polycrystalline solar cells consist of many crystals. Monocrystalline solar cells are generally somewhat more efficient than polycrystalline solar cells, but are also somewhat more expensive to produce.
Crystalline solar cells are highly efficient at converting solar energy into electrical energy, especially in direct sunlight. They are robust and durable and have a long service life. They are used in many different applications, including generating electricity for personal use, powering buildings and powering satellites in space.
The short-circuit current (Isc) is a term used in photovoltaics and refers to the maximum current that can be generated by a solar module or solar cell when the cell is short-circuited. This means that the connections of the solar cell are directly connected to each other so that the current can flow without load.
The short-circuit current is influenced by many factors, including illuminance, temperature and load. As a rule, the short-circuit current is measured under standard test conditions (STC), which specify an illuminance of 1000 W/m² at a cell temperature of 25°C.
The short-circuit current is an important parameter when evaluating the performance of solar cells and modules, as it represents the maximum achievable output of the cell or module under ideal conditions. However, the actual current generated by a solar cell or module depends on many factors, including irradiation and temperature, and can therefore vary under different conditions.
In practice, the short-circuit current is used to calculate the maximum power of solar cells and modules by integrating it into the I-V characteristic curve together with the open-circuit voltage (Uoc) and the maximum power point (MPP).
In photovoltaics, the unit "kVA" is often used to indicate the rated power of inverters. "kVA" stands for kilovolt ampere and is a unit of apparent power that measures the combined active and reactive power of an electrical system.
In photovoltaics, the rated power of an inverter is usually specified in kilovolt amperes (kVA) to indicate the maximum power that the inverter can convert. This rated power is often specified by the manufacturer and indicates the maximum amount of power the inverter can convert, regardless of the actual power of the connected photovoltaic modules.
More about the kVA unit in our report.
"kWh" stands for kilowatt hour and is a unit of energy. It is often used in connection with the consumption of electrical energy.
A kilowatt hour corresponds to the amount of energy consumed in one hour by an appliance with an output of one kilowatt (kW). For example, if an appliance with an output of 1 kW runs for one hour, it consumes one kilowatt hour of energy.
The kilowatt hour is a common unit on electricity bills that measure the energy consumption of households and businesses. It is also used in the energy industry to measure the production of electricity from power plants or renewable energy sources.
"kWp" stands for kilowatt peak and is a unit used in photovoltaics (PV) to measure the output of solar systems.
The output of solar cells and modules is usually measured in watts (W). However, as the output of solar modules is heavily dependent on ambient conditions such as irradiation and temperature, it is difficult to compare the output of solar modules operating under different conditions.
The unit "kWp" was therefore introduced to make it possible to compare solar systems under standard test conditions (STC). One kilowatt peak corresponds to the power generated by a solar module at STC, i.e. with an irradiation of 1000 watts per square meter and a cell temperature of 25 degrees Celsius.
A charge controller (also known as a solar regulator or solar charge controller) is a device used in photovoltaic (PV) systems to regulate the charging and discharging of batteries.
In a PV system, the inverter converts the direct current generated by the solar modules into alternating current in order to make it usable for household consumption. A charge controller ensures that the batteries used to store surplus electricity are not overcharged or deeply discharged, which would reduce their service life.
There are basically AC and DC charging stations. AC charging stations generally supply electricity with an output of 3.7 to 22 kilowatts (kW) and are suitable for charging electric vehicles with a lower output, such as electric cars for city traffic. DC fast charging stations, on the other hand, can supply power of up to 350 kW and make it possible to charge electric vehicles in a short time.
Charging stations (also called charging points or chargers) are facilities used to charge electric vehicles (EVs). They are usually installed in public places such as parking lots, shopping centers or gas stations and allow EV drivers to charge their vehicles when they are on the road. They are eligible for subsidies when purchased.
To be able to cut peak loads or prevent outages, it can make sense to use load management in the company. This measurement and control technology can be connected upstream of all consumers and automatically initiates defined processes if the load peaks become too high. In this case, the previously developed load shedding scheme intervenes. It serves to avoid costly changes to the company's infrastructure, keep manufacturing and production processes efficient and avoid downtimes.
The load profile is a graphical representation of electricity consumption patterns over a certain period of time. It typically shows the variation in electricity consumption over the course of a day, a week or a year and can be plotted as power (in kilowatts) over time (in hours).
Load profiles are important for the planning and management of electricity grids as they help to understand the load and demand for electricity and to allocate resources accordingly. They are often used by utilities, grid operators, regulators and other stakeholders in the energy sector to forecast and efficiently manage the demand for power generation, transmission and distribution capacity.
Electricity load can vary by region, season, day of the week and time of day and is influenced by various factors, including weather conditions, industrial activities, commercial use, household consumption, public holidays and other social and economic factors. Load profiles can therefore vary greatly and need to be updated regularly to reflect current consumption patterns.
More about the Load profile as a basis for calculation in our report.
A peak load occurs at a time when a company consumes an extremely large amount of electricity. This happens, for example, when various machines are started at the same time. A company's grid charges are based on the peak loads and are calculated by the electricity suppliers. Currently, grid charges account for around 25% of total electricity costs and are calculated using the maximum average power consumed within 15 minutes. Reducing these peak loads saves companies money. Cutting peak loads is also known as peak shaving.
The open-circuit voltage is the voltage measured at the terminals of an open voltage source. It is therefore the voltage on the output side when no load is connected and no current is flowing. As a result, no voltage drops across the internal resistance of the voltage source. The open-circuit voltage is also referred to as the original voltage.
A power optimizer is a device used in photovoltaic (PV) systems to ensure that each solar module within the system operates at maximum power.
In a typical PV system, the solar modules are connected in series so that the current must flow through each module before it is conducted to the inverter and finally to the power grid. However, if one module is not working optimally due to shading, dirt or other factors, this can affect the performance of the entire system.
By using power optimizers, each module can be operated independently of the other modules so that the output of each module is optimized. This ensures that the system as a whole operates as efficiently as possible, resulting in higher power generation and lower operating costs.
Power optimizers can also help to extend the service life of solar modules, as they offer the possibility of detecting and rectifying module performance problems at an early stage.
The power tolerance for PV systems refers to the range of permissible deviations from the nominal power of the solar modules. The nominal power indicates the maximum power that a solar module can generate under standard test conditions (STC). The power tolerance refers to the deviation from this nominal power under real operating conditions.
Typically, the power tolerance is specified as a percentage of the nominal power. For example, a solar module with a nominal output of 300 watts can have an output tolerance of +/- 3%. This means that the module can generate between 291 watts and 309 watts under real operating conditions.
The power tolerance is an important factor when planning PV systems, as it has an impact on the expected power generation. A solar module with a higher power tolerance may be more cost-effective, but there is also a higher risk of power losses. It is therefore important to consider the power tolerance when selecting solar modules and decide whether a higher price for solar modules with a lower power tolerance is justified.
An arc in PV systems refers to an electrical arc that can occur in a photovoltaic (PV) system. An arc is a discharge of electric current between two electrodes that are separated by an insulating medium, such as air. It occurs when a voltage difference between the electrodes is high enough to ionize the insulating medium and allow the current to flow.
In PV systems, arcing can be caused by various factors, such as
Faulty or damaged cables and connectors: If there is a cable break or damage to the connectors, an uncontrolled discharge of the current can occur, which generates an electric arc.
Dirt or moisture: Dirt, dust or moisture can impair the insulation capability of components in the system and thus increase the likelihood of arcing.
Overvoltages: Lightning strikes in the vicinity of the system can lead to overvoltages, which in turn can cause arcing.
Shading: Shading on the solar modules can affect the current flow and cause hotspots, which can also promote arcing.
An uncontrolled arc can lead to damage to the PV components, such as damaged cables, connectors or solar modules. It also poses a safety risk as it can cause fire. For this reason, PV systems are usually equipped with safety devices, such as circuit breakers or arc protection devices, which detect the arc and shut off the current flow to prevent damage. Such protective devices are important to ensure the reliability and safety of PV systems.
LiFePO4 stands for lithium iron phosphate and refers to a type of lithium-ion battery that is used in various applications due to its properties.
Lithium iron phosphate batteries have several advantages over other lithium-ion batteries such as Li-ion and Li-polymer. For example, they are safer, more stable and have a longer service life. They are also more environmentally friendly as they do not contain toxic cobalt, which is used in some other lithium-ion batteries.
LiFePO4 batteries are often used in applications such as electric vehicles, energy storage systems for solar installations, stationary power supplies and portable electronic devices. They are known for their high energy density, long service life, short charging times and low self-discharge.
Although LiFePO4 batteries are slightly more expensive compared to other lithium-ion batteries, they are a preferred choice in many applications due to their safety and service life.
A lithium-ion battery is a type of rechargeable battery that uses lithium ions as the electrochemical material to store and release electrical energy.
Lithium-ion batteries are used in a variety of applications due to their high energy density and the ability to charge and discharge them several hundred times. They are particularly useful in portable electronic devices such as smartphones, laptops, tablets and digital cameras.
Lithium-ion batteries consist of several cells arranged in a circuit. Each cell contains an electrolyte and a positive cathode material (usually lithium metal oxide) and a negative anode material (usually graphite or lithium titanate). When the battery is charged, a current flows through the cells, moving lithium ions through the electrolyte and between the cathode and anode materials. When the battery is discharged, the lithium ions flow in the opposite direction, generating electricity.
There are different types of lithium-ion batteries, including lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4) and lithium iron phosphate (LiFePO4). Each type has different properties and is preferred for certain applications.
LSME sustainability reports are reports produced by small and medium-sized enterprises (SMEs) to outline their sustainability practices and performance. These reports include information on environmental, social and economic aspects of the company and show how it contributes to sustainable development.
Find out more in our blog post on LSME and VSME sustainability reports for SMEs.
S
The SAIDI value stands for "System Average Interruption Duration Index" and is a key figure used in the electricity supply industry to indicate the average duration of power interruptions per customer within a certain period of time.
The SAIDI value is usually measured in minutes per customer per year. It indicates how long, on average, a customer is without power supply per year. The lower the SAIDI value, the more reliable the power grid is, as fewer power outages occur and these last for a shorter period of time.
The SAIDI value is an important indicator of the quality and reliability of the power supply of a grid operator or power supply system. A low SAIDI number indicates that the power grid is well maintained and measures have been taken to minimize power outages.
The Science Based Targets initiative (SBTi) is a global organization that supports companies in setting science-based climate targets to limit global warming to well below 2°C, ideally to 1.5°C. SBTi ensures that the targets set by companies are in line with the Paris Agreement and contributes to the reduction of greenhouse gas emissions.
Find out more in our SBTi Blog post.
Unbalanced load in PV systems refers to the uneven distribution of the load on the three phases of the electricity grid. If the load on one phase is higher than on the other two phases, this is referred to as unbalanced load.
This can be a problem for PV systems in particular, as they are usually designed as single-phase or three-phase systems and uneven load distribution on the individual phases can lead to an overload on the phase in question. An overload can lead to a reduction in the service life of the electrical components and an increased risk of power failures.
It is therefore important to monitor the unbalanced load in PV systems and ensure that the load distribution on the three phases of the electricity grid is balanced. This can be achieved through the use of intelligent control and load distribution as well as through suitable dimensioning and design of the system.
Snow load refers to the weight load that a snow cover can cause on a photovoltaic system. The snow load depends on various factors, such as the thickness and consistency of the snow cover as well as the construction and inclination of the photovoltaic module.
In regions with heavy snowfall, the snow load can become a problem for photovoltaic systems, as too high a load can damage the module or the entire system or even cause it to collapse. For this reason, manufacturers of photovoltaic modules and planners of photovoltaic systems in regions with snowfall must take the snow load into account and design the system accordingly.
The snow load is usually specified in kilograms per square meter (kg/m²) and is regulated in the building regulations. In Germany, for example, the snow load is between 50 and 200 kg/m², depending on the region and altitude.
To reduce the snow load, photovoltaic systems can be erected with a high inclination so that the snow cover slides off more quickly. Snow clearance by manually removing the snow cover from the modules or by switching on the heating for certain modules can also help to reduce the snow load.
It is important that the snow load is taken into account when planning, installing and maintaining photovoltaic systems in order to avoid damage to the system and hazards to the surrounding area.
The low-light behavior describes the behavior of photovoltaic modules under low irradiation conditions, such as diffuse radiation or cloudy skies. The performance of photovoltaic modules depends heavily on the intensity of the incident sunlight, so it is important to understand the behavior in low light.
Photovoltaic modules have a characteristic curve that shows the relationship between the current and the voltage under different irradiation conditions. In low light, the characteristic curve of the photovoltaic modules shifts downwards, which means that the power generated is lower than under optimum irradiation conditions. This also means that the voltage and current of the modules decrease in low light.
The reason for the low-light behavior lies in the physical properties of the solar cells. The electrons in the solar cells have a certain amount of energy to detach from the atoms and flow through the electrodes. In low light, however, fewer electrons have enough energy to exceed this threshold and therefore less electricity is generated.
Low light performance is an important factor in the planning and design of photovoltaic systems, especially in countries or regions with a high number of cloudy days. It is therefore important to select photovoltaic modules that perform well in low light conditions to ensure maximum energy yield. Furthermore, the use of additional optimization measures, such as microinverters or power optimizers, can reduce low-light performance.
Sector coupling connects the energy consumption sectors - electricity, heat, transport and industry - in order to use renewable energy more efficiently. In this way, surplus green electricity can be fed into other sectors, e.g. for heat generation or charging electric vehicles. The aim is flexible, low-emission energy use across all sectors. Find out more in our report Sector coupling - for holistic energy concepts.
Silicon is a semiconductor material most commonly used in the photovoltaic industry to manufacture solar cells. It is the second most common element in the earth's crust and is abundantly available, making it a cost-effective and reliable choice for the solar industry.
Most commercial solar cells consist of two layers of silicon, usually referred to as p-type and n-type silicon. P-type silicon has a shortage of electrons and is doped with atoms such as boron to create a positive charge. N-type silicon, on the other hand, has an excess of electrons and is doped with atoms such as phosphorus to create a negative charge.
When the p-type and n-type silicon layers are joined together, a p-n junction is created, which allows electrons to flow from the n-type silicon into the p-type silicon. This flow of electrons creates a DC voltage, known as the photovoltaic effect. The solar cell then converts the incident sunlight into electrical energy, which is usually output as direct current (DC).
Silicon is an ideal material for the production of solar cells due to its ability to conduct electrons and absorb photons. It is also a stable and reliable material that lasts a long time and is well suited for mass production. However, the development of new technologies and materials in the photovoltaic industry can help to increase the efficiency of solar cells and further reduce costs.
A smart meter, also known as an intelligent meter or digital meter, is an electronic device that measures the flow of electricity and automatically transmits the data to the utility company. Unlike traditional analog meters, which must be read manually, smart meters can provide data in real time and allow consumers to closely monitor and control their energy consumption.
Smart meters can also be used as part of a smart grid system, enabling utilities to better manage energy demand and optimize supply. They can also play an important role in integrating renewable energy sources such as solar or wind energy into the electricity grid, as they make it possible to better balance the electricity demand of consumers and producers and control the flow of electricity.
Further information can be found in our Blog post.
Snail trails is a term used in the solar industry to describe the phenomenon where dark lines appear on the surface of solar cells or photovoltaic modules. These lines can sometimes be arranged in spiral-like patterns, giving them the name "snail trails".
Snail trails are caused by a process known as electromigration. Electromigration occurs when electrons in the silicon of the solar cells or module accumulate metallic impurities as they migrate through the current flow. These impurities can come from various sources, such as the soldering of solar cells on a module carrier plate, contacting or metal connections.
Snailtrails can reduce the efficiency of solar cells and modules by increasing the reflection of sunlight, reducing the absorption of light by the solar cell or module and impairing energy production. In addition, the appearance of snail trails can be considered a quality defect.
To avoid snail trails, it is important to maintain a clean production environment and minimize the contaminants that lead to electromigration. The use of high-quality materials and processes can also help to reduce the risk of snail trails.
The cost of a solar system depends on various factors, such as the size of the system, the type of solar cells used, the type of installation (roof or ground-mounted), the number of inverters, the type and number of batteries (if any) and other factors.
The cost of installing solar systems has fallen considerably in recent years, making them an economically attractive option for private households and businesses. The price per watt peak (Wp) has fallen in recent years due to technological advances and higher efficiency of solar cells and modules. The Wp price is currently around EUR 0.40 - 0.70, depending on the size and type of solar cell.
It is also important to note that the cost of installing solar systems can be reduced through various funding programs and incentives. In Germany, for example, there is the KfW program for the promotion of renewable energies, which offers grants and favorable loans for the purchase and installation of solar systems.
It is advisable to seek advice from an experienced full service provider in order to obtain an accurate estimate of the cost of a solar installation.
Solar roof tiles, also known as solar roof tiles or photovoltaic roof tiles, are special roof tiles that contain integrated solar cells and can therefore be used to generate electricity. In contrast to conventional solar panels that are mounted on the roof, solar roof tiles can preserve the appearance of the roof and make it look more aesthetic.
Solar roof tiles are usually made of glass or ceramic and are installed in the same way as conventional roof tiles. They can be manufactured in different shapes, sizes and colors to meet the individual needs and requirements of the house or building.
The solar cells in the solar roof tiles convert sunlight into direct current, which is then converted into usable alternating current by an inverter. The electricity produced can either be used directly, stored in batteries or fed into the power grid.
Solar roof tiles offer many advantages over conventional solar systems, such as better aesthetics, a longer lifespan, greater durability and better integration into the roof. However, they are generally more expensive than conventional solar systems and often require specialized installation methods.
Solar irradiance refers to the amount of solar energy that reaches a certain area on the earth's surface. Irradiation can be measured in a horizontal or inclined position, depending on whether the solar panels are installed flat on the ground or on a sloping roof.
Irradiation depends on various factors, such as the geographical location, the season, the weather and the time of day. Irradiation is usually measured in kilowatt hours per square meter (kWh/m²) and indicates how much energy per unit area per time interval reaches the earth's surface.
Irradiation is an important factor in the planning and dimensioning of solar systems, as it determines the maximum output that can be obtained from the solar cells. Higher irradiation means higher output, while lower irradiation results in lower output. Therefore, countries or regions with higher irradiation are generally better suited for the use of solar energy.
A solar generator is a system that converts solar energy into electrical energy. It usually consists of solar cells mounted on a frame or panel, an inverter that converts the direct voltage of the solar cells into alternating voltage, a charge controller and a battery storage unit to store the energy generated.
The solar cells in the solar generator are usually made of silicon and convert solar energy directly into electrical energy when light falls on them. Depending on the size of the solar generator, it can produce a certain amount of electrical energy that can be used to power electrical appliances or as part of a power grid.
A solar generator can come in a variety of sizes and configurations, from small portable units to large, stationary installations. Solar generators are often used in remote areas or for outdoor activities where a power supply is not available. They can also be used as a backup power source in emergencies or as part of off-grid solar systems.
Solar cables are special cables used in the installation of solar systems to transport direct current (DC) from the solar cells to the inverters. Solar cables are characterized by high UV resistance and excellent weather resistance to withstand the harsh outdoor conditions.
They are usually double insulated to ensure they are protected from moisture and the elements. Solar cables can also be flame-retardant to minimize the risk of fire and are usually equipped with high-quality connectors that enable quick and safe installation.
Solar cables are available in different sizes depending on the size of the solar installation and the distance over which the electricity needs to be transported. It is important that solar cables are correctly sized to minimize losses and overheating and to ensure efficient power transmission.
Overall, solar cables are an important component in the installation of solar systems and help to ensure that solar power is transported safely and efficiently from the solar cells to the inverters.
More about the Wiring of PV modules in our report.
A solar cadastre is a database that contains information on the potential of building roofs or other areas for generating electricity from solar energy. It is often part of the efforts of municipalities, cities or communities to promote the use of renewable energies and reduce greenhouse gas emissions.
A solar cadastre can contain various types of information, such as
The size, orientation and inclination of roof surfaces or other potential solar surfaces
The annual solar radiation and the associated electricity generation on these areas
An assessment of the potential for generating electricity and reducing CO2 emissions through the installation of photovoltaic or solar thermal systems
Information on possible funding opportunities or tax incentives for the installation of solar systems
A solar cadastre can be useful for private individuals, companies or public institutions to determine the potential of their buildings or areas for generating electricity from solar energy and to estimate the profitability of a solar installation. It can also help to simplify and speed up the process of planning and installing solar systems by making it easier to find suitable locations and providing important information.
A solar collector is a technical device for converting solar energy into thermal energy. It is typically installed on the roofs of buildings and can be used to heat water, heat rooms or even generate electricity.
There are different types of solar collectors, but most consist of a flat, dark absorber surrounded by a transparent housing. The absorber is usually filled with a heat transfer medium that absorbs the heat energy from the sun and transfers it to a heat exchange system.
A well-known example of solar collectors are flat-plate collectors, which are mounted on the roof and can be used to heat water. These collectors consist of a flat absorber that is protected by a transparent cover that allows sunlight to penetrate. Under the absorber is a pipe system through which water flows to heat it.
Another type of solar collector is the tube collector, which is similar to a flat-plate collector but uses several glass tubes instead of a flat absorber to capture the sun's rays and transfer them to a heat transfer medium.
Overall, solar collectors are an effective way of harnessing renewable energy from the sun and generating heat energy. They can help to reduce energy consumption and environmental impact.
A solar module is a component of a photovoltaic system that consists of a large number of solar cells. It converts solar energy into electrical energy, which is then stored in a battery or fed directly into the power grid.
A solar module typically consists of a frame containing several solar cells. The solar cells are made of a semiconductor material, usually silicon, which generates electrical energy when illuminated by sunlight. The cells are fitted with connection cables, which are usually connected to an inverter that converts the direct voltage into alternating voltage that can be used in the power grid.
A typical solar module has a nominal output of 100 to 400 watts and an efficiency of around 15 to 20 percent. The size of the modules can vary depending on the manufacturer and requirements.
Solar modules can be installed on the roofs of buildings or in open spaces. They are durable, low-maintenance and can reliably generate electricity for decades. They are a clean and renewable source of energy and help to reduce greenhouse gas emissions.
A Solar park is a large system for generating solar energy that consists of a large number of solar modules and is usually installed on open spaces. The modules are arranged in rows or blocks and can have an output of several megawatts up to several hundred megawatts.
A solar park can be operated either by a single company or by a group of companies. In some cases, the solar park can also be operated by a city, a municipality or a government.
The solar modules in the solar park are typically connected to a network of inverters that convert the direct current generated by the modules into alternating current that can be fed into the electricity grid. The energy generated is either sold to the local electricity supplier or supplied directly to customers such as industrial companies or cities.
Solar parks have many advantages, including the ability to generate large amounts of clean energy.
Solar potential refers to the amount of solar energy available at a particular location that can be used to generate electricity. It depends on various factors, such as geographical location, climate, solar radiation and the nature of the landscape.
Various methods can be used to determine the solar potential of a location, including solar cadastres, solar maps and solar simulations. These tools use data on solar radiation and the topography of the terrain to calculate how much energy can be generated by solar installations.
Solar potential is an important factor in the decision to install solar, as it can affect the profitability and viability of the project. Locations with high solar potential can offer a high return on solar investment, while locations with lower solar potential may be less attractive.
Solar potential can also be used by state authorities and energy companies to determine the potential for renewable energy sources in a region and to develop plans for the expansion of solar energy.
A photovoltaic cell is the basic element of photovoltaic modules and converts sunlight directly into electrical energy. The photovoltaic cell consists of a semiconductor material, usually silicon, which is divided into two layers with different charges.
When sunlight hits the cell, some of the energy is absorbed and the electrons in the semiconductor layer are freed from their atoms and set in motion. The charge separation between the two layers creates an electric field that causes electrons to move from the negatively charged layer to the positively charged layer, generating a current.
A single photovoltaic cell can only generate a limited amount of electrical energy, so several cells are arranged in a module to generate more electricity. Depending on their size and configuration, modules can produce different amounts of energy.
Photovoltaic cells are an important technology for generating renewable energy and are used in a wide range of applications, from small portable devices to large solar installations.
Rafters are components of a building's roof truss to which the roof cladding is usually attached. When installing photovoltaic systems on a roof, the rafters must be taken into account as they form the supporting structure for the system.
Fastening photovoltaic modules to the rafters is a common method for installing solar systems on pitched roofs. The modules are attached to special mounting rails, which in turn are screwed to the rafters.
To ensure that the rafters can support the weight of the solar system, they must be carefully checked before the system is installed. In some cases, it is necessary to reinforce the rafters to cope with the additional load of the solar system.
When planning a photovoltaic system on a pitched roof, it is important to consider the positioning of the rafters and their load-bearing capacity to ensure that the system can be installed safely and no damage is caused to the roof.
Standard Test Conditions (STC) are a standardized method for measuring the performance of photovoltaic modules. The STC define the conditions under which the performance of photovoltaic modules is measured to enable a comparison between different modules.
The STC include a solar radiation of 1000 watts per square meter, a cell temperature of 25 degrees Celsius and an air mass of 1.5. The air mass refers to the length of the sunbeam through the earth's atmosphere before it hits the solar cell. An air mass of 1.5 means that the sunbeam covers a distance that is 1.5 times longer than the direct distance from the sun to the earth.
The STC conditions serve as a reference standard for evaluating the performance of photovoltaic modules. The output of a module under STC conditions is referred to as the nominal output and is measured in watt peak (Wp). The rated power indicates how much power a module can produce under STC conditions.
It is important to note that the STC conditions do not always correspond to the real conditions under which a photovoltaic system is operated. The actual performance of a photovoltaic system depends on many factors, including the intensity of the solar radiation, the temperature, the air mass, the inclination and orientation of the solar cells and the module as well as the condition of the system.
The radiation spectrum in photovoltaics describes the spectral composition of the solar radiation that hits the solar cell and thus influences the electrical power generated. Solar radiation consists of different wavelengths, which are described by the spectrum of electromagnetic radiation. The radiation spectrum is usually divided into three ranges: the ultraviolet (UV) range, the visible range and the infrared (IR) range.
Most commercially available solar cells are most efficient in the visible range, where most photons can be absorbed with the right energy to create electron-hole pairs. The amount of radiation in the visible range varies depending on weather conditions and location, so it is important that solar cells perform well in different radiation spectra.
A string in photovoltaics refers to a group of solar cells connected in series to produce a higher voltage. The solar cells are usually arranged in modules or panels, and multiple modules can be connected together to form a solar array. Within each module, the solar cells are arranged in strings and these strings are usually connected in parallel to allow maximum current flow.
A string can consist of any number of solar cells, but all solar cells in the string must be identical so that they can be connected in series. If a solar cell is damaged or defective, this can affect the performance of the entire string. By using strings, photovoltaic systems can be designed to generate a higher voltage and thus reduce energy loss due to cable resistance.
The term "electricity cloud" refers to a platform or service that enables the trading of electricity from renewable energy sources such as photovoltaic systems. This is a digital platform that enables providers of renewable energy such as photovoltaic systems to sell the electricity they generate directly to customers without having to rely on conventional energy supply companies.
Via an electricity cloud, owners of photovoltaic systems can sell their surplus electricity to other users, who can use this electricity directly or feed it into their electricity grid. These platforms enable consumers to purchase electricity directly from producers, which can lead to lower costs and greater transparency regarding the origin of the electricity. At the same time, the use of electricity clouds can facilitate the integration of renewable energy into the electricity grid and help reduce carbon emissions.
In a photovoltaic system, the current flow describes the path that the electric current takes from the solar cells through the inverter into the power grid or into a battery. The current flow begins when sunlight hits the photovoltaic modules and releases electrons in the solar cells, which are then moved in a certain direction by an electric field. The DC voltage generated is then fed via the cable connections to an inverter, where it is converted into AC voltage. The energy generated is then either fed into the public grid or stored in a battery for later use.
The flow of electricity within the photovoltaic system depends on various factors, such as the intensity of the solar radiation, the temperature of the solar cells, the resistance in the cable connections and the settings of the inverter. Proper installation and maintenance of the photovoltaic system is therefore important to ensure a smooth flow of electricity and maximum energy yield.
Levelized cost of electricity (LCOE) is a measure of the cost per kilowatt hour (kWh) of electricity generated. The LCOE takes into account the investment costs for the construction and maintenance of an electricity generation plant, the fuel or raw material costs, the operating costs and the expected electricity production.
In the case of photovoltaics, the electricity generation costs take into account the costs for the solar cells, the solar module, the inverter, the mounting system as well as the installation and maintenance costs. As solar energy is free and available in unlimited quantities, the fuel costs for photovoltaics are zero.
The LCOE is an important factor when deciding which type of power generation system is the most economical. Due to falling prices for photovoltaic modules and improvements in technology, the LCOE of photovoltaics is also falling continuously, making it more competitive compared to other power generation systems.
The price of electricity in Germany is made up of three main components: electricity procurement and distribution costs, which account for around 20-25 % and cover the purchase and distribution of electricity; grid fees for the operation and expansion of the electricity grids; and government levies and taxes such as the EEG levy, electricity tax and VAT, which make up a large proportion of the end consumer price. Together, these components determine the price that consumers pay. You can find an overview in our report Electricity price components 2025.
The electricity price brake is a political measure in Germany aimed at limiting the rise in electricity prices and ensuring a socially fair distribution of the costs of the energy transition. The electricity price brake limits the amount of the EEG surcharge (Renewable Energy Sources Act surcharge) that consumers have to pay on their electricity bills to finance renewable energies. The EEG surcharge is stabilized by various mechanisms, such as limiting subsidies for new renewable energy plants or exempting energy-intensive industries from paying the surcharge.
The electricity price brake was introduced in 2014 and has been adjusted several times. The aim of the measure is to keep the costs of the energy transition affordable for consumers and at the same time drive forward the expansion of renewable energies in Germany.
Electricity storage systems for photovoltaic systems are used to store the surplus electricity generated from solar energy so that it can be used later when there is little or no solar radiation. Electricity is stored using batteries or other storage technologies such as pumped storage plants or hydrogen storage.
The size of the electricity storage system depends on the electricity consumption of the household or business. The larger the storage unit, the more solar energy can be stored, resulting in greater independence from the electricity grid.
The advantage of using electricity storage systems is that the self-generated electricity does not have to be fed into the grid, which has the advantage that you have to pay less or no charges and taxes to the grid operator. In addition, the self-generated electricity can be used when it is needed, which reduces dependency on the electricity grid and can therefore also reduce the electricity bill.
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