Solar panels can be found on the roofs of more and more cities and communities. In Germany alone, solar systems with a total capacity of around 60 GW (gigawatts) were installed at the beginning of 2021 – equivalent to the output of around 60 large power plants! By 2035, the installed capacity is even expected to increase to around 200 GW. This would mean that the power grid would have more capacity than it does now, including electricity from nuclear and coal-fired power plants. But solar power is produced during the day, and mainly consumed in the morning and evening – so where should the excess electricity at midday be stored?