The Communal building supply is a flexible and low-bureaucracy model for using solar power directly in the building, without the electricity using the public grid. In contrast to the classic tenant electricity model, the operator here takes over not the role of a full-service provider. Instead, the PV electricity from a central plant (e.g., on the roof) is split and distributed to multiple tenants on a property. The remaining electricity will continue to be purchased through individual supply contracts.
The GGV was introduced in mid-2024 as an alternative to EEG tenant electricity – without tenant electricity subsidy, but with lower administrative effort. This model is particularly suitable for commercial properties, multi-family buildings, or owner associations. It allows for cost savings through Avoided grid fees as well as on-site CO₂ reduction.
Fundamentals of Communal Building Services
In contrast to the classic Tenant electricity model entfällt bei der Gemeinschaftliche Gebäudeversorgung die spezifische EEG-Förderung durch den Mieterstromzuschlag. Stattdessen profitiert das Modell von simplified regulations for internal power distribution in buildings. It is regulated by § 42b Paragraph 6 of the EnWG as well as by the Solar package I of May 8, 2024.
The core principle of communal building supply is Voluntariness. The tenant is free to decide whether or not to participate in the GGV. Tie bar prevents lease agreements from being terminated if a tenant wants to leave or is not participating at all. Also when choosing the Standby current suppliers is every tenant free. The GGV merely supplements this supply contract with a „building electricity share“ from local generation.
This applies, as with the tenant electricity model, the spatial limitation. Electricity generation and consumption must therefore take place within the same building or building complex, area, or neighborhood, without using the public grid. Distribution and billing will be carried out via dynamic or static Distribution key with maximum 2 years term. PV surplus electricity can be EEG feed-in tariff sold to the public grid.
Additionally relevant is the Metering Point Operations Act (MsbG) for the Messing infrastructure and grid operator requirements for registration. Only in this way can the GGV bypass many supplier obligations such as balancing group management or electricity tax liability. Therefore, the technical measurement concept implementation is essential here.
Technical Implementation of Shared Building Supply
In the technical implementation of the Communal Building Supply (GGV), the system can be divided into four levels. These are: Generation, Measurement concept, Datenverarbeitung/Abrechnung and Interface to the public network.
The PV system will be installed behind the house connection, feeds into the internal building distribution, and is connected via its own Generation meter captured. There is also a common Summation counter (Building Network Connection Point) and individual apartment/Commercial meter. These are equipped with modern measuring devices or intelligent metering systems (iMSys) so that load flows can be balanced on a quarter-hourly basis.
The core of the GGV measurement concept is a computational division of the generated PV electricity among the participating units. In a static model e.g., a fixed distribution key (based on usable area, connected load, or agreed quota) is applied per month or year to the measured consumption of the participants. In a dynamic model The simultaneous quarter-hourly consumptions of the participants are reconciled with the respective PV generation. The available PV electricity is distributed algorithmically proportionally until it is either completely consumed or depleted. The remaining demand is automatically covered by the respective supplier. Technically, this is done via a gateway (iMSys backend or energy data platform) that collects all meter readings, assigns PV quantities, and generates billing-relevant data records.
For the Network connection It is crucial to clearly distinguish between building power (internal distribution within the customer's system) and grid power. The total meter at the grid connection point measures the net amount of power drawn from or fed into the public grid. Any surplus from the PV system that is not consumed by the participating end consumers within a quarter-hour period, according to the GGV model, is automatically fed back in as feed-in and is billed according to EEG. At the same time, the participants' metering points must be integrated in such a way that their suppliers can continue to balance accurately; from the supplier's perspective reduced a GGV in the result merely the network-related power consumption its customers, without him having to be part of the internal distribution system.
At the operational level, technical implementation requires a clear division of roles. A Plant operator (e.g., owner, homeowner association, cooperative, or service provider) operates the PV system and, if applicable, the storage system, a metering point operator provides the iMSys and the communication connection, and a GGV Service Provider or Billing service settles the building's electricity quantities against the participants. In practice, this means: early coordination with the grid operator and metering point operator, well-planned metering concepts (single-line diagrams and meter plans), and an IT solution that reflects both energy industry requirements (quarter-hourly values, market communication) and consumer-friendly invoices.
Advantages of GGV
Communal building supply offers a significant advantage in considerably lower energy industry complexity compared to the classic tenant electricity model. The operator becomes not to a Energy supplier with balancing group and electricity tax obligations, but rather it is an internal distribution model where the tenants' supply contracts remain in place. This means reduce liability risks and Fixed costs for landlords, homeowners' associations, or developers, while still covering a relevant portion of consumption with inexpensive PV electricity from the roof.
In addition, a visible contribution to the decarbonization of the building, the better marketability „green“ and modern commercial spaces or apartments. The main factor, however, is the direct financial benefit for participating tenants compared to pure grid electricity procurement. They avoid grid fees and surcharges on the building's electricity share.
Disadvantages of GGV
Since there is no tenant electricity subsidy, the economic viability should be calculated based on the avoided grid fees, electricity costs, or feed-in tariffs. The GGV is legally and technically subject to conditions, such as smart metering systems and quarter-hourly Data collection and relative short contract terms (maximal two years), the technical and organizational effort is somewhat higher than with a classic tenant electricity model.
One disadvantage or. Uncertainty factor For the operators, it is the non-mandatory participation of tenants. If parties want to leave or switch, the calculated self-consumption rate and thus the project's economic viability can worsen. Especially smaller housing cooperatives or landlords without service providers in the background quickly reach their limits, meaning that GGV often only pays off in practice with standardized solutions or specialized partners.
Conclusion & Outlook
Community building energy supply offers an efficient middle ground between individual self-sufficiency and tenant electricity. It is easy to implement without full utility obligations and with clear economic benefits for operators and tenants. It strengthens the attractiveness of buildings, reduces operating costs, and enables visible CO₂ savings that can be directly passed on to tenants and users.
The only challenge lies in technically sound metering infrastructure, which, however, is becoming increasingly simpler due to the growing rollout of intelligent metering systems. Future adjustments in the Solar Package II and the further development of the EnWG are likely to further enhance the model's clarity and attractiveness. This makes the GGV a practical standard for modern commercial and residential properties.