Exergy analysis and sensitivity study of a PV/T -air source heat pump coupled heating system under cold climates

Photovoltaic/thermal (PV/T) and air source heat pumps (ASHP) are widely recognized as promising clean heating technologies to achieve carbon neutrality in building sectors. Nevertheless, their large-scale application is severely restricted by solar intermittency and ASHP frosting and performance degradation in cold and humid climates. To address this issue, a PV/T-ASHP combined heating system was previously proposed and carried out studies on capacity matching optimization, economic performance and regional adaptability, but lacked a systematic analysis from the second law of thermodynamics. To fill this research gap, this paper adopts a PV/T waste heat preheating evaporator antifrosting structure and conducts a comprehensive exergy analysis to quantify exergy destruction distribution, evaluate component efficiencies, and reveal the effects of ambient temperature, relative humidity and preheating temperature on system performance. Results demonstrate that compressor and evaporator are the dominant exergy loss components, accounting for 38.6% and 22.55% respectively. The preheating strategy reduces evaporator exergy destruction by up to 44.3% at −10 °C. System exergy efficiency ranges from 41.2% to 49.3% under −10∼10 °C and is most sensitive to ambient and preheating temperature. This study provides essential theoretical guidance for performance optimization and engineering application in cold and humid heating regions.