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. Also, a comparative study of the performance of this system has been undertaken theoretically. Simulations have been made with BASIC computer program of three basic combined configurations, as well as conventional solar and conventional heat pump systems in Trabzon by using meteorological data. The experimental results were obtained from December to May during the heating season for four heating systems. These systems are a conventional solar system, a series heat pump system, a parallel heat pump system and a dual source heat pump system. The experimentally obtained results are used to calculate the collector efficiency, heat pump coefficient of performance (COP), seasonal heating performance, the fraction of annual load met by free energy, storage and collector efficiencies and total energy consumption of the systems during the heating season. (C) 1999 Elsevier Science Ltd. All rights reserved.