Experimental Study on Direct Expansion Solar Assisted Heat Pump System Based on PV/T Panel

This study experimentally investigates the operational characteristics of a direct expansion solar assisted photovoltaic/thermal (PV/T) heat pump system under varying conditions. A setup employing 380Wp PV/T modules was developed to analyze the effects of solar irradiance, ambient temperature, and electrical efficiency on power output, heat collection, and heat pump performance, establishing empirical correlations. Empirical correlations were established to characterize these relationships. Results indicate that PV/T module temperature reduction, relative power generation gain, heat collection power, thermal collection factor, and system coefficient of performance (COP_sys) increase with elevated solar irradiance and ambient temperature. Conversely, power generation efficiency decreases with higher ambient temperature, while the heat collection factor declines with increased solar irradiance. Furthermore, COP_sys is inversely proportional to PV/T module electrical efficiency. Within the test range, the system exhibited electrical efficiency, relative power generation gain, and heat collection factor of 17.98% to 19.64%, 1.04% to 12.16%, and 51.18% to 870%, respectively. The heat pump achieved a COP_sys range of 1.32 to 5.73, representing a variation of −27.79% to 27.03% compared to an air-source heat pump. When considering combined power generation and consumption, the system demonstrated a lower heating energy consumption factor (0.03 to 0.76) than air-source heat pumps during daytime operation.