Application of a multi-function solar-heat pump system in residential buildings

In this study, a multi-function solar photovoltaic/thermal (PV/T)-heat pump system was designed and established to supply energy for residential buildings. The system could realize different functions by operating in different modes, such as heating in winter, cooling in summer, domestic water heating for a whole year, and part of household electricity demand. System performance was experimentally investigated. Results showed that the average overall efficiency of PV/T collector was more than 50% for PV/T water heating mode when solar irradiance was sufficient, thereby indicating the good performance of the PV/T collector. Under experimental conditions, the coefficients of performance (COPs) of PV/T-WSHP heating mode and PV/T-W&ASHP heating mode were 3.18 and 2.53, which were much higher than the COP of ASHP heating mode with 2.23. The difference was attributed to that the addition of solar energy could improve evaporating temperature of heat pump system. Therefore, different operating modes could be activated, thereby realizing the maximum possible energy conservation. In conclusion, the system could fully utilize solar energy and realize advantageous complementarities between solar energy and heat pump by cascade energy utilization. The data and analysis could provide a reference for the combination form between solar PV/T system and different heat pump systems.