Houses with solar cells on the roof.

Photovoltaics and power stores: a clever combination


Photovoltaics and power stores: a clever combination

May 15, 2019

If you’re thinking about getting an electric car, then you’ll probably think about where you can charge it. Of course, charging it at home is the most convenient option. Self-sufficient charging stations with a private photovoltaic system and power store are one possible solution. Find out here whether it could work for you.

Discover here:

  • How you could benefit from generating your own solar power – and using it yourself
  • How much power a photovoltaics system can supply to an electric car
  • How power store owners can get together
  • How photovoltaics are providing an impetus for electric mobility

Anyone who produces power with solar power cells on their own roof in Germany will receive a fixed sum for any power they feed into the grid. This is all thanks to the Renewable Energy Act. When it was first introduced in 2000, the Renewable Energy Act allocated 50 cent for solar power, but now the state pays out 12 cents per kilowatt hour (kWh). In contrast, renewable energy from the socket costs almost three times as much.

Using as much as your own self-generated solar power yourself can therefore pay off. And that is precisely why solar power and electric cars complement one another perfectly: there is no cheaper way to recharge your battery than at home on the drive or in the garage. However, only around one quarter of solar power can be used directly – because the sunshine is at its strongest when you’re out and about in your electric car, for instance. So, it doesn’t make much sense to use expensive green power from energy providers in the evening. The alternative: using a power store in the form of a big battery. This saves energy during the day and releases it at night so you can charge your electric car, for instance.


Smiling woman at home on her sofa.
Rich in energy: for owners of photovoltaics systems, it makes sense to use self-generated power yourself.

Photovoltaics get electric cars up and running

On average, a power store increases the producer’s consumption by at least 50 percent while simultaneously decreasing procurement from a supplier by 60 percent.→. The market research company “EUPD Research” has found that ownership of a photovoltaics system including a battery store also has a positive impact on intentions to buy an electric car →. Experts even regard PV system owners as early adopters for electric cars. After all, the annual output of a PV system with 3,000 kilowatt hours of power → can run an electric car emissions-free for around 14,000 kilometres. According to the German Association for Solar Industries, most of all new solar power systems are installed in conjunction with a battery. This also opens up a potential business model for owners: why not offer up your own connection as a solar charging station for your neighbours? However, home owners have been unable to benefit from promotion for batteries from KfW Bank since 2019. Nevertheless, the purchase of a photovoltaics system is still supported with low-interest loans and a repayment bonus →. According to Solar Cluster Baden-Württemberg e.V., a photovoltaics system currently costs around EUR 1,300 per kWp (kilowatt peak) while a solar power battery costs around EUR 1,200 per usable kWh.

Intelligent networks of batteries

Detached houses in a village environment.
Digital village community: Households can share power on a virtual sharing platform.

There are a wide range of power stores available. With the market leader “Sonnen” → users can do more than just charge from their own charging box using solar power, they can also have their electric car become part of a community: a virtual sharing platform connects customers so they can share their excess power. This includes households with a solar energy system and power store as well as people who only produce green power or simply want to buy it. In smart mode, the intelligent control unit uses an interface with the power store to calculate the best possible charging time for the electric car, taking the household’s consumption and weather forecasts into account. If the house isn’t producing enough power, energy is procured from the community. Meanwhile, the provider “Senec” relies on the system “Cloud to Go” →: owners of PV systems and stores can credit their unused power to a virtual account. If they have to purchase external power, they get the credited amount back for free. The credit can also be used at public charging stations in Germany and abroad.

Impetus for wide-scale electric mobility

A total of 40,000 power stores were installed in Germany in 2018. →. If you add all home storage owners – around 110,000 – together, you get a battery capacity of almost 1,000 megawatts. This is about the same power as a large pumped storage plant. Scientists from Braunschweig Technical University → assume that privately owned solar energy systems and PV batteries can create a comprehensive network of charging points for electric vehicles. If everything is connected up in an intelligent network, the amount of wiring and network expansion required could decrease significantly. In the study → researchers come to the conclusion that the charging capacity would double compared to a classic low-voltage distribution grid. In suburbs with large numbers of detached and semi-detached houses, 60 percent of households could already be supplied with its own 11 kW charging station for electric cars. However, to achieve this, the decentralised batteries would have to be allowed to receive power from the general supply grid and then give it back again. The underlying legal conditions and options for support were recently established by the EU. In future, this concept could also be used to supply all private charging points in villages. And then electric mobility could become a reality in rural areas, too.