A solar-assisted heat pump system (SAHPS) for hot-water production has been developed and compared for its experimental performance, under similar ambient conditions with a conventional thermosyphon solar system (CTSS) with a single direct tank. Both systems were monitored from 1993 to 1997 during summer and winter time periods. The performance of CTSS was seriously a¤ected by weather conditions, whereas SAHPS could always operate with no signiÞcant variation and with a COP above 3)0. A comparison between the two systems proved the performance of the SAHPS to be better than that of CTSS under all climatic conditions