Central solar heating plants with seasonal storage (CSHPSS) are capable of covering more than 75% of the annual heat demand of housing areas if appropriate storage technologies are available. The maximum design temperature should be 90-95 degrees C and the long term cost goal is 100 DM m(-3) for a storage volume larger than IO 000 m(3) water equivalent. Three pilot projects are presently under construction and planning in Germany with 600, 4500 and 12 000 m(3) volume. The storage medium in all three cases is water. A first pilot heat storage with about 600 m(3) volume is being built in Rottweil. This small scale project will be applied as short term storage in connection with a combined heat and power (CHP) plant. The storage container is made of concrete, water tightness is achieved by a stainless steel liner and mineral wool is used as insulation. The aim of this project is to demonstrate the feasibility of the technology and to gain practical experience for the construction of larger stores. During 1995/96 two full scale central solar heating plants with seasonal storage (CSHPSS) of this type will be built in Hamburg, North Germany and Friedrichshafen, South Germany, with 4500 and 12 000 m(3) storage volume, respectively.