(Updated April 2026) Modernity Solar cells achieve in practice today Efficiency levels of approximately 20–23% for standard modules. However, the actual output of a photovoltaic system depends not only on the cell itself, but also on what is known as the performance ratio (PR). In modern systems, this typically ranges between 80 and 90%, and indicates the proportion of the theoretically possible energy that is actually generated.
The most important thing in brief
- Standard modules (monocrystalline): approx. 20–23% efficiency
- Performance ratio of modern systems: approx. 80–90 %
- Biggest Losses: Temperature, Inverter, Shading
- Space efficiency is crucial for economic viability
- Efficiency alone is not decisive for the yield
What does efficiency mean for solar cells?
The efficiency describes how much of the incident solar energy is converted into electrical energy.
Example:
An efficiency rating of 20 % means that 20 % of solar energy is converted into usable electricity.
Important: The efficiency refers only on the solar cell, not on the entire plant.
What is the Performance Ratio (PR)?
The performance ratio is the Key performance indicator for the overall performance of a PV system.
She describes the relationship between:
- generated electricity
- theoretically possible current under ideal conditions
Modern systems achieve today: approx. 80–90 % Performance Ratio
Losses arise, among other things, from:
- Inverter (~2–4 %)
- Cabling (~1–2 %)
- Temperature losses
- Pollution
- Shading
How have efficiency ratings evolved?
- 1980s: approx. 10–15% cell efficiency
- 2000s: approx. 15–18 %
- today (standard modules): approx. 20–23 %
- High-end modules: up to approx. 24 %
In the lab:
- Tandemzellen: >30 %
- Mehrfachzellen: >40 %
Important for practice: these high values are not economically available for serial production.
Which types of solar cells are relevant today?
Monocrystalline solar cells (standard in commercial use)
- Efficiency: approx. 20–23 %
- highest area efficiency
- Standard for Industrial and Commercial Facilities
Polycrystalline solar cells (hardly relevant anymore)
- Efficiency: approx. 17–20 %
- largely crowded out of the market today
Thin-film modules
- Efficiency: approx. 10–13 %
- Advantages: lightweight, flexible
- Use: Special applications (e.g. Building-integrated photovoltaics)
What factors influence efficiency in practice?
1. Temperature (very important)
- Performance degradation: approx. 0.3–0.4 % per °C
- High module temperatures = lower yield
Therefore, facilities in temperate climates are very efficient.
2. Shading
- Even small shadows can cause big losses
- Crucial in planning (simulation, string sizing)
3. Pollution
- Typical losses: 2–5 %
- significantly higher with flat roofs
A regular Photovoltaic cleaning enhances efficiency and value retention.
4. Degradation
- modern modules: approx. 0.3–0.5 % per year
- After 20 years, it typically still delivers ~85–90 % of power
With regular maintenance and, if necessary, replacement of the modules, the Degradation of PV systems relatively low according to the latest studies.
5. System Losses
- Inverters, wiring, etc., add up to a total loss of approximately 5–10 % in yield
How important is efficiency for companies with a PV system, really?
In short: The Efficiency is important – but not solely decisive.
Much more important for economic efficiency are:
- Share of own consumption
- Electricity price level
- System Size
- Load profile
- Integration into the energy system (e.g. Large-scale battery storage)
Space efficiency: How much power fits on the roof?
Typical guidelines:
- monocrystalline: approx. 5–6 sqm per kWp
- polycrystalline: approx. 6–7 m² per kWp
- Dünnschicht: >15 m² pro kWp
Modern modules increase surface efficiency and have 420–600 W per module today.
Is repowering worthwhile due to improved efficiencies?
A Repowering PV systems are sometimes worthwhile – but not automatically. It can be worthwhile if:
- the facility is older than 10-15 years
- the performance ratio is between ~75 and 80 %
- Roof renovations are pending
- new modules deliver significantly more power per area
It often doesn't make sense if:
- the system still works well
- Feed-in tariff is high (old plants)
Conclusion
The efficiency of solar cells has significantly improved in recent decades. However, for the economic viability of a photovoltaic system, not only the cell efficiency is decisive, but also the interplay of system efficiency, location, usage, and integration into the energy system.
Companies should therefore not only focus on efficiency but also strategically optimize the entire system and its utilization.
Energy Newsletter
Always stay up-to-date!
Your advantages:
✓ Latest news on renewable energies
✓ Updates on energy law & subsidies
✓ Expert knowledge on PV and sustainability topics