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Glossary · Energy industry & energy transition

Collective building supply (Gemeinschaftliche Gebäudeversorgung)

collective building supply tenant electricity photovoltaics Self-Consumption prosumer multi-family house electricity supply

Collective building supply (Gemeinschaftliche Gebäudeversorgung, GGV) is a distinct model in Germany under § 42b of the Energy Industry Act (Energiewirtschaftsgesetz, EnWG). Several final consumers in a building use electricity from a shared solar installation. The law calls this installation a building electricity installation (Gebäudestromanlage). Under the definition in § 3 EnWG, it is a generation installation in, on or at the building or an associated ancillary facility that generates electricity from solar radiation. The model is therefore limited to solar power, in practice to photovoltaics on the roof, on the façade, on a garage or on a carport. Other generators such as combined heat and power plants are not covered. The rules were introduced in 2024 with the Solar Package I (Solarpaket I). They are aimed at multi-family buildings, condominium owners' associations, commercial buildings and mixed-use buildings.

Statutory requirements

Under § 42b (1) EnWG, a final consumer may use electricity from a building electricity installation within the GGV if four conditions are met together:

  • The electricity is used without being routed through a grid, and specifically in the same building or an ancillary facility of the building on which the installation is installed.

  • The electricity comes directly from the installation or from a storage unit that is likewise installed at this building or an associated ancillary facility.

  • The final consumer's electricity consumption quantities are measured every quarter of an hour.

  • The final consumer has concluded a building electricity use contract (Gebäudestromnutzungsvertrag) with the operator of the installation. Only then is the consumer a participating final consumer within the meaning of the law.

The building electricity use contract contains three things: the right to use the solar power including the allocation key, whether and in what amount a fee in cents per kilowatt-hour is paid, and rules on the operation, maintenance and servicing of the installation. If a community of condominium owners operates the installation, a resolution under the Condominium Act (Wohnungseigentumsgesetz) can replace the contract. The other requirements then apply accordingly.

Allocation in 15-minute intervals

The core of the model is the allocation on paper. The solar power is not collected over the year but distributed for each 15-minute interval. In each case, the smaller of two quantities is allocated: the solar power generated in that quarter of an hour, or the total consumption of all participants in that time. The distribution follows the agreed allocation key. If nothing clear has been agreed, all participants receive equal shares. No one can be allocated more solar power in a quarter of an hour than they themselves consumed in that time. The operator reports the allocation key to the body responsible within electronic market communication.

An example: Between 12:00 and 12:15 the installation generates 4 kWh. Two participating apartments each have a key of 50 percent. Apartment A consumes 3 kWh in this time, apartment B only 0.5 kWh. On paper, each apartment is entitled to 2 kWh. However, B is allocated at most 0.5 kWh, A receives 2 kWh and draws 1 kWh through its own electricity supply contract. The remainder goes into the grid as feed-in. Whether unused shares are redistributed to other participants depends on the chosen key. A dynamic key is based on actual consumption, a static one uses fixed quotas. Physically, it is not possible to trace which kilowatt-hour flows into which apartment. The allocation results solely from measured values and billing rules.

Because measurement must take place every quarter of an hour, in practice intelligent metering systems (smart meters) are usually needed at all metering points involved. According to industry reports, grid operators and metering point operators have not implemented these metering concepts promptly everywhere. Implementation therefore depends heavily on the local metering point operator.

Not a full supplier: distinction from tenant electricity

The most important difference from tenant electricity (Mieterstrom) under § 42a EnWG: with tenant electricity, the provider generally delivers the entire supply, including residual electricity from the grid. With the GGV, the operator expressly does not have to ensure the comprehensive supply of the participants. At the start of the contract, however, the operator must point out to them that the installation cannot cover their demand completely and not at all times. For the remaining consumption they therefore need their own electricity supply contract. This contract with an electricity supplier of their choice may not be restricted in the building electricity use contract. If the installation is out of operation for a longer period for reasons other than weather or time of day, the operator must provide timely information, and likewise when it resumes operation.

For this reason, many supplier obligations do not apply. §§ 40, 41 (1) to (4), (6) and (7) as well as § 42 (1) EnWG do not apply, including the requirements on invoice contents, on contract design and on electricity labelling. The billing provisions of §§ 40a and 40b apply accordingly. However, monthly, quarterly or half-yearly billing does not have to be offered. From the tenant electricity rules, § 42a (2) and (3) apply accordingly, with the exception of individual sentences. The price cap for tenant electricity in § 42a (4) is not referenced. According to the wording of the law, there is therefore no statutory price limit for the GGV. In addition, § 42b expressly excludes § 21 (3) EEG. As a result, there is no tenant electricity surcharge (Mieterstromzuschlag) for the GGV.

The GGV also differs from classic self-consumption. With self-consumption, the operator uses the electricity itself. With the GGV, operator and user are separate: the landlord, owners' association or a service provider operates the installation, and the participants use the electricity. The GGV is distinct from energy sharing via the public grid because it expressly works without routing through a grid. As soon as electricity flows through the public grid, different rules apply (see Energy Sharing).

Technical implementation and limits

Technically, the solar installation, a possible storage unit and the participating consumption points are located behind a common grid connection point. Anyone who does not participate remains an entirely ordinary grid customer in the building. Participation is voluntary and requires a contract. Surpluses go into the grid and are remunerated or marketed according to the rules applicable at the time.

The GGV does not mean self-sufficiency. At night, in winter and at high simultaneous demand, electricity comes from the grid. In summer, surpluses often arise at midday. A battery storage system in the building can increase the locally used share because it shifts energy by a few hours. It does not compensate for longer dark periods or seasonal differences. The degree of self-sufficiency of a building is therefore a different indicator from the installed capacity of the installation. How much solar power is actually used in the house also depends on whether consumption can be shifted in time. This concerns, for example, water heating, heat pumps or charging points, if they are controllable and there are incentives for flexibility.

Economically, the model is worthwhile because solar power used in the building replaces more expensive grid electricity. The system is nevertheless not free of charge: the installation, metering technology, billing and maintenance cost money. The grid connection and residual electricity supply remain necessary. For residents, the model is only attractive if the price per kilowatt-hour is below their normal electricity purchase and the conditions are understandable. Participation here means first and foremost a right of use and a price advantage, not automatically ownership or a say in decisions.

Legal uncertainty after the customer installation ruling

In November 2024, the Court of Justice of the European Union ruled that the German definition of the customer installation (Kundenanlage) is not compatible with EU law. The Federal Court of Justice (Bundesgerichtshof) subsequently interpreted the term narrowly in its decision of 13 May 2025 (EnVR 83/20). The EnWG amendment of late 2025 brought a temporary transitional rule for existing customer installations. How this affects the GGV is assessed differently. Some expert contributions see the GGV as also affected. Others state that the framework for the GGV remains unchanged. There is broad agreement that concepts spanning several buildings or plots of land are primarily affected. For new projects, the legal classification of the cable network in the building should therefore be examined on a case-by-case basis (as of November 2026).

Assessment

The GGV is intended to make solar power usable on multi-party buildings without the operator having to become a full supplier. In this way, tenants and condominium owners without a roof of their own can also become prosumers. Properly understood, it is a model that allocates solar power on paper: spatially limited to one building, dependent on the simultaneity of generation and consumption in 15-minute intervals, and still integrated into the grid, metering and residual electricity supply. It does not replace the public grid.

Sources

Related glossary entries

Edited by eCMS on 12.11.2026 05:05

© 2026 Erik Schmidt. All rights reserved. Quotations with a link to the source are welcome.