Collective self-supply (gemeinschaftliche Eigenversorgung) · Glossary

Collective self-supply (gemeinschaftliche Eigenversorgung) is a collective term for supply models in which several final consumers draw electricity from a jointly used generation installation. They often also have a storage unit. Typical cases are a photovoltaic installation on an apartment building, a rooftop installation operated by a homeowners' association, or an installation whose electricity is shared with neighbours, municipalities or small businesses. The term does not describe a specific technology. It describes how generation, consumption, metering, billing and responsibility are divided among several participants.

In German law, collective self-supply is not a legal term in its own right. Anyone using the term should therefore state which specific model is meant. In Germany, there are mainly three models: tenant electricity supply under § 42a EnWG, collective building supply under § 42b EnWG, and shared use via the public grid under § 42c EnWG. In the EU context, one speaks of jointly acting self-consumers or of collective self-consumption. The precise requirements are set in each case by national law.

Distinction from individual self-supply

In classic self-supply, the same person or the same legal entity operates the installation and consumes the electricity itself. One example is a homeowner with a solar installation on their own roof. In collective models, the operator and the consumers are no longer the same person. Tenants of a building do not become self-suppliers merely because an installation is on the roof. A commercial tenant in the neighbourhood is not one merely because the installation is nearby. From a legal perspective, there is usually an electricity supply or a contractually regulated use. The obligations and costs depend on which model is chosen. The term self-supply is therefore meant here only colloquially. It does not automatically carry the privileges that the law provides for self-supply in the narrow sense.

The three German models at a glance

Tenant electricity supply (§ 42a EnWG): The installation operator or a service provider supplies the residents with solar electricity and, as a rule, also the residual electricity from the grid. The provider thereby largely takes on the role of an electricity supplier. For electricity from solar installations on residential buildings, a tenant electricity surcharge under § 21 paragraph 3 EEG may be available.
Collective building supply (§ 42b EnWG): Participants receive a calculated share of the electricity from the building electricity installation. They obtain their residual electricity from a supplier of their choice. The tenant electricity surcharge under § 21 paragraph 3 EEG is expressly excluded for a building electricity installation.
Energy sharing (§ 42c EnWG): Electricity from renewable energies is shared with other final consumers via the public distribution grid. Since 1 June 2026, distribution system operators have been required to make this possible within their balancing area.

Collective building supply: the rules in detail

§ 42b EnWG was introduced with the Solar Package I. The model has narrow requirements. The electricity must not be routed through a grid. It must be used in the same building or in an ancillary facility of the building on or at which the installation is installed. A storage unit is permitted if it is also located there. Each participant's electricity consumption must be metered every quarter of an hour. In addition, each participant concludes a building electricity use contract with the operator. In it, both agree on an allocation key, a possible charge in cents per kilowatt hour, and rules on the operation, maintenance and servicing of the installation.

The allocation is a calculation; it does not move any electricity. In each 15-minute interval, only the smaller of two quantities is distributed: the quantity of electricity generated or the total consumption of all participants. No participant can be allocated more than they themselves consumed in the same interval. If the contract does not clearly provide otherwise, the allocation is made in equal shares. The operator does not have to ensure comprehensive supply. However, it must point out to the participants that additional electricity from the grid remains necessary. The contract may not restrict the free choice of supplier for this residual electricity. Several supplier obligations of the EnWG apply only to a limited extent. In buildings with condominium ownership, a resolution of the owners' association can replace the individual contract.

Energy sharing via the public grid

§ 42c EnWG implements EU requirements on the shared use of renewable energy. The provision entered into force on 22 December 2025. Since 1 June 2026, distribution system operators have been required to enable energy sharing within their balancing area. Later, shared use is also meant to become possible across directly adjacent distribution grids. Such an installation may be operated by natural persons and certain partnerships or legal entities. Their shareholders or members must be final consumers or public-law bodies. Businesses may participate as customers only if they are small, medium-sized or micro enterprises.

Energy sharing requires two contracts: an electricity supply contract and a contract on shared use. The model is therefore a supply with facilitations and not self-supply in the narrow sense. For small installations, obligations under §§ 5 and 40 to 42 EnWG do not apply. This applies if a household customer operates an installation of no more than 30 kilowatts. In multi-unit buildings, the limit is 100 kilowatts for an installation operated by residents of the same building. Because the electricity flows through the public grid, the grid and balancing remain involved. According to the available sources, § 42c does not regulate whether lower grid charges apply to shared electricity. Specialist articles from 2026 report on pilot projects and open questions in market communication.

Customer installation and grid boundary

How local a model is depends legally on the boundary between the building's internal installation and the grid. Consumption within the same building is something different from consumption via a customer installation (Kundenanlage) spanning several buildings. Both, in turn, are different from using the public distribution grid. On 28 November 2024, in Case C-293/23, the Court of Justice of the European Union ruled that the German definition of the customer installation then in force is not compatible with the EU concept of the distribution system. The Federal Court of Justice (Bundesgerichtshof) adopted this in May 2025. Accordingly, supply within a single building continues to be regarded as largely unproblematic. For neighbourhood solutions across several plots of land, however, the legal situation has become uncertain. The legislator has meanwhile redefined the customer installation in the EnWG. A further judgment of the Court of Justice from September 2026 on direct lines is currently being examined for what it means for neighbourhood projects.

Metering and allocation

Electricity physically flows according to the electrical conditions of the lines. It does not flow to where a contract provides. Who economically receives which electricity is therefore determined solely by measured values and allocation rules. For this reason, § 42b and § 42c require metering in quarter-hours. In practice, this requires smart metering systems and virtual metering points. Metering point operation is therefore a central building block. If there is no reliable metering concept, disputes arise over shares, residual electricity and the feed-in of surpluses.

Economic viability, flexibility and limits

A model is economically worthwhile above all when generation and consumption coincide in time. Participants can save on price components of grid electricity, provided the electricity volumes stay within the building. Surpluses generate revenue from feed-in. In addition, part of the electricity price becomes predictable over the long term. Set against this are costs for metering, billing, administration and contract design. With few participants, frequent tenant turnover or low consumption, a project can therefore become uneconomical. A battery storage system can shift solar electricity from midday to the evening. Heat pumps or charging points can shift part of their demand into the generation hours. However, this flexibility depends on control, comfort requirements and tariffs. It is not available without limit.

Collective self-supply does not make participants independent of the electricity system. Photovoltaics generates little electricity in winter and at night. The grid connection, the supply of residual electricity and balancing therefore remain necessary. § 42b EnWG even expressly requires that participants be informed of this limit. Politically, the term is linked to the aim that tenants and other people without a roof of their own can also share in affordable local generation. Whether this succeeds depends on a balancing of interests. The obligations must not overburden small projects. But they must also not fall so far that consumer protection, cost transparency or a fair distribution of grid costs suffer.

Sources

§ 42b EnWG – Gemeinschaftliche Gebäudeversorgung — Bundesministerium der Justiz / Bundesamt für Justiz (gesetze-im-internet.de); unbekannt (aktuelle Fassung, abgerufen 11.11.2026). § 42b Abs. 1 bis 6 EnWG
§ 42c EnWG – Gemeinsame Nutzung elektrischer Energie aus Anlagen zur Erzeugung von Elektrizität aus erneuerbaren Energien — Bundesministerium der Justiz / Bundesamt für Justiz (gesetze-im-internet.de); unbekannt (aktuelle Fassung). § 42c Abs. 1, 2 und 7 EnWG (Auszug im Suchergebnis)
Energy Sharing: Wenn der Strom vom Nachbarn kommt — BDEW Bundesverband der Energie- und Wasserwirtschaft; unbekannt (2026). Abschnitte „Seit wann gibt es Energy Sharing“ und „Wer kann mitmachen“
Energy Sharing under § 42c EnWG: A legislative milestone, framework conditions and next steps — Forschungsstelle für Energiewirtschaft (FfE); unbekannt (2026). Einleitung und Fazit
EuGH klärt Direktleitung und stärkt Kundenanlagen — Haufe; unbekannt (ca. Oktober 2026). Abschnitte zur Kundenanlage und zum EuGH-Urteil vom 17.9.2026

Related glossary entries

Edited by eCMS on 12.11.2026 05:05