Buildings are increasingly becoming small power plants, since photovoltaic modules capture solar energy on more and more roofs. But the sun doesn't always shine and the demand for electricity fluctuates greatly over the year. Storage technologies are therefore in demand. Geothermal probes provide heat in winter, but no electricity. Batteries, on the other hand, make technical sense, but they are short-term storage devices and therefore not seasonal electricity storage devices. With the Seebrighof development in Hausen am Albis, the electricity works of the canton of Zurich are therefore taking a different, new approach. The 28 apartments in the attached farmhouse and the new building draw solar energy from the roof of the house. So that this is also available in winter, EKZ is installing a hydrogen storage facility – one of the first of its kind in Switzerland.

If, on summer days, the solar system delivers more electricity than the residents consume, it does not get back into the grid. Instead, the power-to-gas plant uses it to make hydrogen. In winter, when the energy requirement is higher, the system converts the hydrogen back into energy. "In the fuel cells of the plant, around 55 percent of this electricity is generated," explains Georg Putzi, Product Manager Energy Contracting<\/span> at EKZ. The remaining 45 percent of the stored energy escapes as waste heat, which heats the building.<\/p>

Seasonal electricity storage offers several advantages. The system is environmentally friendly because it only needs tap water and locally produced solar power. The public power grid is relieved. A battery compensates for short-term fluctuations, so the P2G system can be operated more efficiently.<\/p>