Self-consumption of electricity from the photovoltaic system on the roof is becoming more and more important with rising electricity prices. At the same time, the feed-in tariff plays an increasingly smaller role the further it is reduced.
Technical aids can clearly show the self-consumption of solar power, including controlled consumers and power storage. The researchers at the Center for Solar Energy and Hydrogen Research in Baden-Württemberg (ZSW) have determined the potential for self-consumption that homeowners have with heat pumps and batteries.
With smaller solar systems, the self-used solar power increases from 30 to 45 percent with a heat pump for domestic water heating. If a battery is added for the unusable electricity, the figures increase to 70 percent. Larger solar systems allow even higher self-consumption in absolute values when using a storage tank. Other major advantages of self-consumption include relieving the electricity grids through lower feed-in and the reduction in EEG subsidy costs.
You can use 70 percent of the solar power yourself
A family of four with a photovoltaic system that generates 4,000 kWh of green electricity per year has self-consumption of 1,200 kWh without any tools. That’s 30 percent. Deviations of several 100 kWh are possible depending on lifestyle and device usage.
“Own use improves the amortization of the PV system, since the difference between the feed-in tariff and the electricity price benefits the system owner,” says Jann Binder from ZSW.
With a heat pump and thermal storage, profitable self-consumption increases to 1,800 kWh. Plus battery with 5 kWh used energy content, it is 2,800 kWh. According to the ZSW researchers, this requires intelligent control of the heat pump and optimized battery charging.
If the family opts for a larger photovoltaic system that delivers 7,000 kWh, they can use 1,400 kWh themselves without storage. “That is 200 kWh more than with the small system. The percentage drops to 20 percent, since owner-occupation does not grow in proportion to the size of the system, ”continues Binder. With a heat pump, residents improve their consumption to 2,400 kWh for their own purposes. With an additional battery, the value increases to 3,500 kWh, 700 kWh more than in the case of the smaller PV system. The result is 50 percent owner-occupation.
50 percent of the electricity requirement can be generated from solar energy
Statements about the degree of coverage of the entire domestic energy consumption are also possible. In the case of a family of four with 7,000 kWh electricity production per year and the use of both storage systems, 50 percent of the energy requirements for electricity and heat can be covered. A condition is a modern energy standard of the residential building. The requirement here is 7,000 kWh per year, 4,000 for household appliances and 3,000 for heating.