Operating principle

  • The heat is drawn from the water, which is located in a manure pit or another large underground tank, using solar power via a heat pump.
  • In winter, the water cools down to 0°C and freezes.
  • In summer, the ice is thawed via hybrid collectors (PVT) and heated up to 25°C.
  • The storage capacity of such an ice store covers a large part of the heating heat and hot water of the property.
  • Thanks to this seasonal storage, the freely available summer heat can be used cheaply in winter and even cools surrounding houses in summer.


  • The heat capacity of the storage tank is increased fivefold by freezing compared to normal heating of water.
  • Thanks to the optimal use of several heat sources and intermediate storage tanks, the heat pump works optimally with a small temperature stroke.
  • This makes more than six kW of ambient heat usable with one kW of electricity.
  • The 0°C cold ice storage tank practically automatically obtains the heat from the environment in summer.
  • Cold solar cells produce more electricity than those heated by the sun. The water from the ice storage does a good job of cooling the hybrid collectors.
  • Thanks to suitable energy storage systems upstream and downstream of the heat pump, it can run whenever either its own electricity is produced on the roof or when electricity from the grid is cheap.
  • An extremely inexpensive battery storage system provides intermediate storage for the surplus electricity produced during the day.
  • Thanks to the controlled room air system and the ice storage, the house remains pleasantly cool even in summer.
  • With an optional heat exchanger, it is possible to recover the energy in the waste water.
  • Furthermore, rainwater utilisation for toilets, washing machines and the garden is possible, whereby even the heat of the rainwater can be used to defrost the ice tank in summer.