Collective Self-Consumption · Glossary

Collective self-consumption means that several consumers jointly use locally generated electricity. They do not have to own the generation plant themselves. In most cases this involves electricity from a photovoltaic system on a building. This electricity is allocated, in accounting terms, to several households, businesses or institutions. In German it is often called gemeinschaftlicher Eigenverbrauch. EU law speaks of jointly acting renewables self-consumers. This refers to a group of at least two renewables self-consumers in the same building or multi-apartment block.

The term extends classic self-consumption. In that case, a person or company generates electricity and consumes it themselves, for example with a PV system on their own roof. In collective self-consumption, by contrast, several final customers use the same local generation. Typical examples are multi-apartment buildings, condominium owners' associations and mixed-use buildings with apartments and commercial units. In the narrower legal sense, the term is tied to a single building. Sharing across several buildings, a neighbourhood or the public grid is usually regulated separately, for example as energy sharing or within the framework of energy communities.

Measurement is in kilowatt-hours. Generation and consumption are recorded as energy quantities and assigned to time intervals. An annual balance is not sufficient for this. Whether locally generated electricity counts as collectively self-consumed depends on whether generation and consumption occur in the same time interval. In Germany, for collective building supply, this is expressly the quarter-hour. A PV system that generates a lot of electricity at midday therefore does not supply a household in the evening from its own generation, as long as no storage lies in between. The installed capacity of a plant therefore says little about what share of its electricity can be used on site at the same time.

Legal framework in the EU and in Germany

At EU level, the Renewable Energy Directive (EU) 2018/2001, also called RED II, regulates the subject in Article 21. Member States must ensure that self-consumers in the same building, including in multi-apartment blocks, may jointly generate, use, store or sell renewable electricity. They may also exchange the electricity generated on site among themselves. Network charges and other charges and levies may still apply. The plant may be owned or operated by a third party. If self-consumers feed electricity into the grid, they are to bear an appropriate share of the overall system costs. The directive must be transposed into national law. The design therefore differs from country to country.

In Germany there is no uniform legal term "collective self-consumption". Several models exist side by side. Building-related models are above all tenant electricity (Mieterstrom) under § 42a EnWG and collective building supply (gemeinschaftliche Gebäudeversorgung) under § 42b EnWG. For collective building supply, several conditions must be met. The electricity is used in the same building or an ancillary facility without being transmitted through a grid. It comes directly from the building electricity system or from a storage unit at the same building. Electricity consumption is measured every quarter-hour. In addition, a building electricity use contract (Gebäudestromnutzungsvertrag) with the plant operator must exist.

The building electricity use contract sets an allocation key. It also regulates whether a fee in cents per kilowatt-hour is paid for the electricity and who takes care of operation and maintenance. Unless otherwise agreed, the electricity is distributed in equal shares. In each quarter-hour, each party may be allocated at most as much as it itself consumed in that quarter-hour. In total, at most the smaller of the quantity generated and the total consumption of all participants can be allocated.

The operator does not have to supply the participants completely with electricity. However, the operator must point out to them that they need additional electricity from the grid. They are free to choose the supplier for this residual electricity. Several supplier obligations do not apply here. The tenant electricity surcharge under § 21(3) EEG is excluded. If a condominium owners' association operates the plant, a resolution of the owners (WEG resolution) can replace the individual contract.

Energy sharing under § 42c EnWG goes beyond the building. Since 1 June 2026, final customers may also jointly use electricity from renewable plants via the public distribution grid. This applies within the balancing area of a distribution system operator. A supply contract and, in addition, a contract on joint use are required. Here the electricity flows through the public grid. Network charges and levies therefore do not automatically fall away. Industry and research sources currently still regard practical implementation as difficult. The reasons are metering infrastructure and market communication.

Delimitation from self-consumption, tenant electricity and energy community

Collective self-consumption differs from individual self-consumption in the number of parties involved: there are several consumers. It differs from mere electricity sales in its local reference. The focus is on local generation and the local allocation of energy quantities. It is therefore not just about a supply contract. What matters is how locally generated electricity is used within a defined spatial and organisational framework.

Tenant electricity is a related model. Here, electricity from a solar plant on or at a residential building is supplied to the residents. The plant operator generally also takes over the residual electricity and thus the obligations of a full supplier. In return, the operator can receive the tenant electricity surcharge under certain conditions. With collective building supply, it is the other way round. The operator supplies only the proportionate solar electricity. Each party buys the residual electricity itself from a supplier of its choice. This reduces the effort for the operator, but no subsidy is available for it.

An energy community is likewise not the same as collective self-consumption. An energy community can organise generation, consumption, storage and joint investments and in doing so go beyond a single building. Collective self-consumption describes more narrowly the process of locally generated electricity being used jointly. The term prosumer describes someone who both generates and consumes energy. In collective self-consumption, this role is organised collectively. This is socially significant because many people have no roof of their own and no investment capital.

Why local allocation is complicated

Physically, electricity does not follow contracts. The PV system feeds into the building's electrical installation, and all connected consumers draw electricity from this shared system at the same time. How the electricity is distributed depends on network impedances and instantaneous loads, not on billing. Collective self-consumption therefore needs metering, allocation and rules. Only these determine which kilowatt-hours count as locally consumed, which are fed into the public grid and which count as grid withdrawal.

Metering infrastructure is central to this. Meters are needed that record generation and consumption in sufficiently fine time resolution. Examples are smart metering systems that measure every quarter-hour, summation and sub-meters, or accounting by software. Without clear metering, conflicts arise. Who receives which share of the solar electricity? Is it distributed by consumption shares, fixed keys or equal parts? How is the price formed? Who bears the costs of metering point operation, billing and maintenance? These questions decide whether a project remains economically viable and understandable for those involved. A large PV system on a multi-apartment building can make technical sense and still fail because of the effort of contracts and metering concepts.

Significance in the electricity system

Collective self-consumption can increase the share of solar electricity used on site, that is, the self-consumption rate. This works better the more closely the load profile of the participants matches generation. A commercial yard with high daytime consumption suits photovoltaics better than a residential building in which consumption rises mainly in the morning and evening. In residential buildings, the locally used share rises if heat pumps, charging points for electric cars or battery storage are controlled in a targeted way.

The effect on the grid is not automatically positive. A plant can reduce the annual electricity bill of many participants and still produce high feed-in peaks on sunny days. In the evening, electricity withdrawal from the grid can remain high. For grid operation, timing, connection capacity and simultaneity matter. Collective self-consumption changes the economic allocation of electricity quantities. The technical task of balancing generation and consumption at all times remains. Flexibility therefore becomes more important. An electric car that charges during the day uses more solar electricity than one that is only plugged in at night. A heat pump with a buffer tank can run when plenty of solar electricity is available. A battery storage unit shifts electricity by a few hours, but costs money to acquire and causes conversion losses.

Common misunderstandings

Collective self-consumption does not mean self-sufficiency. Even a building with a high solar share remains dependent on the grid: in darkness, in winter, in bad weather and to take up surpluses. In collective building supply, the law even requires pointing out the necessary residual electricity withdrawal.
Local electricity often appears cheaper. However, this is not only due to low generation costs. For electricity that does not flow through the public grid, some charges, levies or distribution costs can apply differently or fall away entirely. For system costs, it must therefore be disclosed which costs actually fall and which are merely distributed differently. The EU directive also requires self-consumers to bear an appropriate share of the overall system costs.
Collective self-consumption is not a purely technical innovation. Modules, meters, inverters and storage are well known. Often more difficult are ownership models, operator roles, supplier obligations, data protection, billing, liability and the distribution of investment risks between owners, tenants, plant operators, metering point operators and suppliers.

Institutional and economic role

Collective self-consumption blurs the classic separation between generator, supplier, grid operator and final customer. Part of the value creation shifts into buildings and local associations. This raises new questions: who operates the plant, who bills, and how are consumer protection and free choice of supplier ensured? For the energy transition the model is important because it gives more people access to solar electricity. Without such models, it is mainly owners of owner-occupied houses who benefit from self-consumption. Tenants, small businesses and institutions without a roof of their own are then left out. Collective models can change this if they are simple enough and the risks do not end up one-sidedly with less informed participants.

Collective self-consumption does not replace a supra-regional electricity supply. Wind energy, large solar parks, grids, storage, firm capacity and system services remain necessary. Local use solves neither the seasonal gap between summer solar production and winter heat demand nor Dunkelflauten (periods of little sun and wind) or regional grid bottlenecks. The term is precise when it takes into account metering, time allocation, grid connection, cost distribution and responsibilities. It then describes an important interface between technology, regulation and social participation.

Sources

Energiewirtschaftsgesetz (EnWG) § 42b Gemeinschaftliche Gebäudeversorgung — Bundesministerium der Justiz / gesetze-im-internet.de; unbekannt (abgerufen 11.11.2026). § 42b Abs. 1 bis 6 EnWG
Richtlinie (EU) 2018/2001 zur Förderung der Nutzung von Energie aus erneuerbaren Quellen (konsolidierte Fassung 16.07.2024) — Europäische Union / EUR-Lex; 2024-07-16 (konsolidierte Fassung). Art. 2 Begriffsbestimmungen (gemeinsam handelnde Eigenversorger); Art. 21 Abs. 2, 4, 5 und 6
Energy Sharing ermöglicht lokales Teilen von Ökostrom — BDEW Bundesverband der Energie- und Wasserwirtschaft; unbekannt (2026). Abschnitte 'Seit wann gibt es Energy Sharing' und 'Rechtlicher Hintergrund'
Energy Sharing under § 42c EnWG: A legislative milestone, framework conditions and next steps — Forschungsstelle für Energiewirtschaft (FfE); unbekannt (Anfang 2026). Zusammenfassung Whitepaper 1

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Edited by eCMS on 11.11.2026 17:50