Energy, economic, and environmental evaluation of a solar-assisted heat pump integrated with photovoltaic thermal modules using low-GWP refrigerants

Solar-assisted heat pumps integrated with photovoltaic thermal modules (PVT-HPs) have been extensively studied owing to their superior heating performance. However, the investigation of PVT-HPs using low global warming potential (GWP) refrigerants to replace R134a is required to comply with environmental regulations. This study aimed to investigate the substitutability of R1234yf, R1234ze(E), and R152a in PVT-HPs based on energy, economic, and environmental analyses. The heating performance of heat pumps using these low-GWP refrigerants was measured. Furthermore, transient simulations were performed using transient system simulation software to determine the annual performance of the PVT-HPs using low-GWP refrigerants. Based on the simulation results, the levelized cost of energy (LCOE) and Specific Life Cycle Climate Performance (SLCCP) were evaluated. R152a was the most economical refrigerant, showing a 50% reduction in LCOE compared to R134a because of its lower electricity purchase cost and higher sale cost. Furthermore, the SLCCPs of PVT-HPs using R1234yf, R1234ze(E), and R152a decreased by 16.8%, 17.5%, and 20.8%, respectively, compared to those using R134a. Accordingly, the refrigerant substitutability index of R152a was the highest at 1.431, owing to its superior economic and environmental performance. In conclusion, only R152a was deemed appropriate for replacing R134a in PVT-HPs.