Yearly performance of a PV-PCM and water storage for domestic hot water energy demand

Abstract

A photovoltaic panel (PV) integrated with phase change materials (PCMs) is a system characterized by a simultaneous production of thermal and electrical energy. PCMs exploit the solid–liquid phase change to store latent heat. In addition, by cooling the PV panel, the electric conversion efficiency increases. This paper experimentally investigates the yearly performance of a PV-PCM system, coupled to a water tank, to provide thermal energy for the domestic hot water (DHW) service of a typical residential building. The solar radiation of a summer and an intermediate month has been reproduced under a solar simulator, while the performance in winter month has been tested outdoor under real conditions. A water circulation system, connected to a water tank, is activated to extract the stored heat, through a copper heat exchanger dipped in the PCM. Different tests are performed varying the size of the water tank storage. Results show that a storage volume of 50 L, 75 L, 100 L and 125 L ensure a reduction of 15.3 %, 21.2 %, 22 % and 21.5 % respectively, compared to traditional fully electric heaters. The same percentages turn out to be 8.2 %, 9.8 %, 10 % and 9.9 % during the intermediate month, while in winter the melting process of the PCM has not occurred. As regard only the PV-PCM and water tank system, the proposed system reached a maximum efficiency of 38 % under the summer climatic conditions and a minimum of 16 % under the winter ones.