Hydrogen plays a particularly important role in the climate-neutral supply of entire urban and residential districts. Green electricity is produced with the help of a photovoltaic system on the roofs of the residential or commercial buildings to be supplied. This supplies the electrolyzer. Here, the surplus electricity is converted into hydrogen and stored. At times when the electricity from the photovoltaic system is not sufficient to supply the residents, the stored hydrogen is converted back into electricity with the help of a fuel cell. The waste heat generated in the electrolyzer and the fuel cell can be used to heat the neighborhood via a local heating network.