Abstract: The introduction of PV modules in the greenhouse structure positively affects the light and heat environment of the greenhouse.In order to investigate the effect of rooftop photovoltaics on the internal environment of greenhouses in all seasons and to obtain the optimal coverage,improve the light and heat environment of the PV greenhouse while increasing the PV power generation,a radiative heat gain model in the greenhouse is developed in this paper,and the accuracy of the model is verified through experiments.Under different coverage rates of PV modules,the proposed PV greenhouse system is used to simulate the indoor irradiance,indoor air temperature and PV power generation for a greenhouse with a top area of 420 m~2 on a typical day.The results show that for every 12.5%increase in PV module coverage compared to no PV modules,the indoor irradiation on the equinox,summer solstice,fall solstice,and winter solstice days was reduced by 2.79%,5.8%,2.90%,0.70%,and daytime indoor air temperatures were reduced by 1.19%,0.54%,0.49%,and 1.12%,respectively.By analyzing the light and temperature conditions required of plant growth,the optimal PV module coverage rates for each typical day was 62.5%,50%,62.5%,and 25%,and the corresponding PV power generation was222.80,228.57,224.00,and 36.05 k Wh.