Performance and application boundary analysis of a solar PV/T heat pump system

The solar photovoltaic/thermal (PV/T) heat pump system is a new type of system that integrates solar PV/T conversion with heat pump technology. It is capable of comprehensive utilisation of solar energy, offers multifunctionality, and has broad application prospects. In this study, a mathematical model of a solar PV/T heat pump system was developed. According to the developed model, the effects of the environmental conditions on the thermal efficiency, net power generation efficiency, total efficiency, coefficient of performance (COP) and electro-thermal ratio of the solar PV/T heat pump system were analysed. The applicable boundaries of the system were determined; and the carbon emission reduction of the system over its entire lifecycle was calculated. The results show that under the reference operating conditions, the system COP can reach 5.11 and that thermal, net power generation, and total efficiencies of the system are 55.7%, 6.57%, and 70.5%, respectively, while the electro-thermal ratio of the system is 0.103. The performance of the system is affected by solar irradiance, ambient temperature, and wind speed in varying degrees. At a given irradiance, the influence of the condensing temperature for the applicable boundary of the system was also analysed. Finally, taking the Lhasa area in China as a case study, the results show that the carbon emission reduction effect was better compared with that of the independent PV system. In this study, the applicable boundary of a solar PV/T heat pump system is determined based on system modelling and analysis, and the entire life cycle carbon emission reductions of the system are calculated.