Mathematical modeling and simulation of a solar-assisted heat pump system based on a direct-expansion photovoltaic/thermal (PVT) module were developed to analyze its annual performance in Shanghai. The direct-expansion collector/evaporator

which couples the heat pump system with the PV module

absorbed the waste heat of the PV module and increased its electricity generation efficiency by reducing its working temperature. By contrast

such coupling enhanced the evaporation temperature and thus the performance of the heat pump. The simulation model

which was developed based on the energy balance and heat transfer feature of the collector/evaporator

was compared to the experimental results and it presented a maximum error of 6.2%. A simulation was performed under the ambient temperature and irradiation conditions of Shanghai taking one day as a time step. The results showed that the COP of the system varied between 2.67 and 9.06

with an annual average value of 5.47. The annually-averaged evaporation temperature was 18.34 ℃

with an annually-averaged thermal efficiency of 100.06%. Additionally

PVT module presented a 20.21 ℃ drop in annually-averaged working temperature compared to the PV module

which benefits the electricity generation by 11.80%.