Solar calculator

With our solar calculator you can easily calculate your level of self-sufficiency - which depends on the size of the PV system and battery storage.

Solar calculator

Many customers ask themselves what contribution a photovoltaic system together with battery storage makes to powering their home. You can estimate the so-called degree of self-sufficiency and self-consumption proportion with our solar calculator. After having entered your annual electricity consumption, you can find out how these two key figures depend on the installed photovoltaic power and the usable storage capacity of the battery storage system.

Annual electricity consumption

The average electricity consumption at the respective project location is reflected in the annual electricity consumption. Normally, the solar system remains in operation for at least 20 years, so an outlook into the future and the possible increase in electricity through the purchase of an electric car, air conditioning or other electrical appliances should be planned for. Here you can enter your annual electricity consumption. The average electricity consumption of single-family households is around 4000 kWh per year. The lower the power consumption, the higher the degree of self-sufficiency that can be achieved.

Photovoltaic power

The photovoltaic output indicates how much solar power is generated by the photovoltaic modules on the roof. In this regard, it should be noted that the maximum possible system performance is limited by the existing roof area. An area of approximately 6.5 square meters is required per kWp (kilowatt peak). The standard dimensions for a solar module are currently around 170 x 110 cm. Thanks to the latest technology, roof surfaces can now be used regardless of orientation, inclination or shading. In this field you can enter the size of the photovoltaic system (nominal power of the photovoltaic modules). The greater the photovoltaic output, the greater the degree of self-sufficiency that can be achieved.

Usable battery capacity

The amount of electricity that can actually be drawn from the battery is known as usable storage capacity. The latter is often stated as gross capacity, but you should be careful here! As a rule, energy storage units can never be completely discharged. Furthermore, it should be noted that the power storage loses capacity over its entire service life, so oversizing by up to 20% is advisable. The usable capacity of a battery storage device can be less than its nominal capacity and should be stated in the manufacturer's data sheet. The larger the battery capacity, the greater the degree of self-sufficiency and the proportion of self-consumption.

Own consumption share

The self-consumption share describes the share of the solar power generated that is either used simultaneously by the electricity consumers or to charge the battery storage system. The higher the share of self-consumption, the less solar power is fed into the grid.

Degree of self-sufficiency

Independence from the energy supplier is indicated by the so-called degree of self-sufficiency. This value indicates what percentage of annual electricity consumption can be covered by clean, self-produced solar power. In Germany, a level of self-sufficiency of up to 80% can currently only be achieved through the use of photovoltaics and electricity storage. The higher the level of self-sufficiency, the less energy is drawn from the power grid.

Direct consumption

Direct consumption is the name given to self-generated solar power that is consumed immediately - i.e. without intermediate storage in the electricity storage system. Direct consumption is the simplest, fastest and lowest-loss form of solar power use. However, direct consumption is not always possible because many consumers are switched off during the day when the sun is shining. A direct consumption rate of 30% is considered very good. This can be increased by smart consumers and the use of smart home components.

Grid feed

Solar power that is not consumed directly (direct consumption) or stored in the electricity storage system for later use (self-consumption) can be fed into the public grid. For this, the system operator receives a feed-in tariff set for 20 years, which is regulated by the EEG (Renewable Energy Sources Act).

Grid reference

Of course, every system operator is always 100% covered. If the solar system does not produce enough electricity and the electricity storage is empty, the consumer automatically receives electricity from the public grid. This current represents the grid supply.