In order to investigate the performance of the combined solar-heat pump system with energy storage in encapsulated phase change material (PCM) packings for residential heating in Trabzon, Turkey, an experimental set-up was constructed. The experimental results were obtained from November to May during the heating season for two heating systems. These systems are a series of heat pump system, and a parallel heat pump system. The experimentally obtained results are used to calculate the heat pump coefficient of performance (COP), seasonal heating performance, the fraction of annual load meet by free energy, storage and collector efficiencies and total energy consumption of the systems during the heating season. Copyright (C) 1999 John Wiley & Sons, Ltd.