Solar Assisted Heat Pump Water Heater Using Photovoltaic-Thermal Collector Evaporator and Its Building Energy Saving Performance

Solar assisted heat pump (SAHP) water heater based on photovoltaic/thermal collector evaporator (PV/T SAHP) can effectively improve the solar energy conversion efficiency by realizing the all-round application of solar energy, PV and photothermal. The heat generated in a PV/T collector evaporator is taken away by the refrigerant and supplied to the heat pump cycle, which can increase the heat pump’s evaporation temperature as well as its performance; meantime, the solar cell’s temperature decreases and the photoelectric conversion efficiency can be enhanced. The performance of PV/T SAHP system is studied theoretically and experimentally, and tested under different conditions. Conventional SAHP and uncooled solar panels are set as the control group. Compared with uncooled solar panels, PV/T SAHP can effectively reduce the temperature of solar cells and improve the photoelectric conversion power. The average error of the numerical simulation model is about 5%, which can meet the needs of engineering application. The optimum installation angle of the collector evaporator in Shanghai is calculated, which is 27°. The annual operation of PV/T SAHP in Shanghai is simulated and predicted. Among them, the average COP is 3.71, the average collecting efficiency is 0.71, and the average comprehensive utilization efficiency of solar energy is 1.04, which can maintain good working performance throughout the year.