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Glossary · Energy industry & energy transition

Self-consumption (Eigenverbrauch)

Self-Consumption photovoltaics storage prosumer electricity consumption distribution grid load shifting heat pump Electromobility

Self-consumption is electricity that a generation installation produces on site and that is consumed behind the same grid connection without flowing through the public grid. The term most often arises in connection with photovoltaic systems on buildings. A rooftop system supplies the consumers in the building first: household appliances, a heat pump, a wallbox, machinery in a business, or a battery storage system. Only the surplus that nobody in the building needs at that moment is fed into the public grid.

Energy quantity and time profile

Self-consumption is usually stated in kilowatt-hours. This is a quantity of energy, not an instantaneous power. However, the annual quantity is not sufficient to assess the effect on the grid. It makes a difference whether a kilowatt-hour is consumed at midday with plenty of solar power, in the evening at high household load, or at night from a storage system. Grid load, balancing and economic value depend on this. Self-consumption therefore always raises the question of how generation and electricity consumption match over the course of the day and the year.

Self-consumption rate and degree of self-sufficiency

Two indicators are often confused. The self-consumption rate states what share of the self-generated electricity is used on site. The degree of self-sufficiency states what share of total consumption comes from own generation. An example: a household consumes 4,000 kWh per year and has a small system that generates 2,000 kWh. Of this it uses 1,600 kWh itself. The self-consumption rate is then 80 percent, but the degree of self-sufficiency is only 40 percent. Conversely, a large system can achieve a high degree of self-sufficiency and still feed in a lot of electricity on sunny days, so that its self-consumption rate is low. Both indicators look at the same energy balance from two sides.

Distinction from related terms

Direct consumption usually means immediate use without intermediate storage. Electricity that is first stored in a battery and used later does count as self-consumption, but not as direct consumption. Eigenversorgung (self-supply), by contrast, is a legal term. Until the end of 2022, the EEG defined it in § 3 No. 19 as follows: a person consumes electricity in the immediate spatial vicinity of the installation, operates the installation themselves, and the electricity is not routed through a grid. This definition was important above all for the proportional EEG surcharge. Since 1 July 2022 the surcharge is no longer levied. With the EEG 2023, the definition and the surcharge rules on self-supply ceased to apply as of 1 January 2023. Self-supply remains possible without the EEG surcharge being incurred. However, other laws, for example in electricity tax law or energy financing law, may apply their own terms and requirements.

With tenant electricity (Mieterstrom), electricity is supplied to third parties in the building or its surroundings, for example to tenants. Because it is supplied and invoiced, this is not self-consumption in the narrow sense. Since 16 May 2024 there has also been communal building supply (gemeinschaftliche Gebäudeversorgung) under § 42b EnWG. Here, residents share solar power from a building installation. The electricity must not be routed through a grid and must be used in the same building, directly or via a storage system in the building. Consumption is metered in quarter-hour intervals and allocated arithmetically according to an agreed key. The operator does not have to supply the residents completely; they are free to choose a supplier for the remaining demand. Such distinctions matter because levies, metering concepts, supplier obligations and tax treatment may depend on them. Models that share electricity via the public grid are covered in the entry Energy Sharing.

Technology and metering

Technically, self-consumption results from the power flows behind the grid connection point. An example: the photovoltaic system is currently generating 5 kW and the consumers in the building need 3 kW. Then 3 kW are used on site and 2 kW are fed in. If the building needs 7 kW, the system covers 5 kW and 2 kW come from the grid. A bidirectional meter records import and feed-in separately. It does not measure self-consumption itself. This is obtained only by calculation as generation minus feed-in, which requires a generation meter or the inverter data. For systems with storage, several consumers or shared use, a metering concept is needed that unambiguously allocates all quantities.

Economic incentive

Self-consumption pays off because a self-used kilowatt-hour replaces expensive grid purchases, whereas a fed-in kilowatt-hour earns only little. Household electricity from the grid contains, besides procurement costs, also grid charges, taxes, levies, surcharges, sales costs and metering charges. For fed-in solar power there is usually only a considerably lower feed-in tariff or a market value. Self-consumed electricity thus saves an expensive purchased kWh instead of producing a poorly remunerated fed-in kWh.

With the so-called Solarspitzengesetz (Solar Peak Act), this incentive has strengthened for new systems in Germany. For systems under 100 kW that have been commissioned since 25 February 2025 and are assigned to the feed-in tariff or the tenant electricity surcharge, a transitional rule applies. Until an intelligent metering system with a control device has been installed and successfully tested by the grid operator, they may feed in at most 60 percent of their installed capacity at the point of connection. The limit applies only to feed-in. Electricity that is consumed in the building or charged into a storage system is not limited. In addition, new systems receive no remuneration as long as the exchange electricity price is negative. According to the current state of affairs, these periods are partly made up for at the end of the support period. Existing systems are in principle not affected by either rule.

Storage and load shifting

Battery storage systems increase self-consumption because they absorb midday surpluses and release them later. However, a higher share of self-consumption does not yet mean that the storage system is also operated well for the overall system or the grid. If it is set only for the highest possible private rate, it is often already full in the morning and can no longer absorb the actual midday peak. Grid-serving operation, by contrast, takes into account charging power, weather forecast, expected consumption and possible grid bottlenecks. With the 60 percent limit, such forecast-based control can additionally prevent electricity from being curtailed.

Load shifting also increases self-consumption. A heat pump can preferentially heat water when there is a lot of sun, an electric car can charge during the day, and refrigeration in a business can be brought forward within technical limits. This makes sense only if comfort, process requirements, battery condition, connection capacity and tariff rules allow it. An energy management system often coordinates these processes. Self-consumption thus becomes a question of flexibility. This does not mean going without, but the controlled time adjustment of consumption or storage within real limits.

Effect on the distribution grid

Self-consumption can relieve the distribution grid if local electricity actually covers local load and, as a result, less power flows through lines and transformers. However, this effect depends on the time of day. In residential areas with many photovoltaic systems, problems usually do not arise because too little is self-consumed on an annual average. They arise because on sunny days with low consumption many systems feed in at the same time. High self-consumption in the evening helps against these midday peaks only if storage systems or controllable consumers absorb the surplus beforehand. For grid planning, what counts is power at particular points in time, not the annual quantity of self-consumption.

Grid dependence and cost distribution

A common misunderstanding is that self-consumption means independence from the grid. Almost all self-consumption systems remain dependent on the grid. They draw electricity in darkness, in winter, at high power demand or when their own components fail, and they feed in surpluses. The grid connection provides capacity, balancing, voltage maintenance and security of supply, even when the quantity of electricity drawn falls. This raises a distribution question: if grid costs are financed predominantly via kilowatt-hours drawn, households with high self-consumption contribute less although they continue to need grid capacity.

The remark that self-consumers relieve the grid does not answer this question. Sometimes they do, sometimes they do not. An appropriate tariff structure distinguishes between energy quantity, connection capacity, time-related grid load and system services. Capacity charges, time-variable grid charges or dynamic electricity tariffs set more precise incentives than pure energy prices. A tariff that values every avoided kilowatt-hour equally also rewards self-consumption in hours when the grid is not under load at all. A time-graded tariff can steer consumption into hours with plenty of renewable electricity or free grid capacity.

From consumer to prosumer

Through self-consumption, pure customers become operators of small generation installations, in part also storage operators and providers of flexibility. The term prosumer has become established for this. However, it says only roughly that generation and consumption coincide. For the electricity system, the following matter more: is the installation controllable, for example via a control box? What metering is in place? Does it respond to price signals? Can it be operated in a grid-serving way, and who is responsible for billing and balancing? A million small installations do not automatically make a coordinated power plant. This requires rules, data, interfaces and clear responsibilities.

Assessment

Self-consumption mobilises investment and visibly brings renewable generation into buildings and businesses. However, it does not replace grid expansion, market design, security of supply or seasonal balancing. Solar self-consumption depends strongly on the season and time of day. Heat pumps, by contrast, need the most electricity in winter, when the sun delivers little. Electric cars increase self-consumption only if they are at the charging point at the right time. Industry and commerce have different load profiles than households. How good a self-consumption concept is therefore depends on the interplay of generation, consumption, storage, control and tariff. Whether an installation has a system-serving, cost-reflective or supply-secure effect is not shown by the term alone. This is determined by the time match between generation and load, the rules on grid charges and feed-in, and whether private optimisation fits the requirements of the grid.

Sources

Related glossary entries

Edited by eCMS on 11.11.2026 19:42

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