Swedish solar heated residential area with seasonal storage in rock: Initial evaluation

Abstract

A partly solar heated building area comprising 50 residential units has been built in Anneberg, Sweden. The system includes low-temperature space heating with seasonal ground storage of solar heat. Heating is supplied by 2400 m 2 solar collectors and individual electrical heaters for supplementary heating. The ground storage comprises about 60,000 m 3 of crystalline rock with 100 boreholes drilled to 65 m depth and fitted with double U-pipes. The collectors will have favourable working conditions but the store is rather small, the estimated heat loss from the heat store is about 40% of stored solar heat and the average solar fraction is estimated to 70% after 3–5 years of operation. An initial evaluation after 2 years of operation shows that, although problems have occurred and several parts seem to work less efficient than expected, the overall system idea works as intended.