Model simulation of thermal environment and energy effects of rooftop distributed photovoltaics

Rooftop distributed photovoltaic (DPV) systems show promise for alleviating the energy crisis resulting from summer urban cooling demands and mitigating secondary hazards associated with urban heat islands. In this study, a parametric scheme for rooftop DPVs was incorporated into the Weather, Research and Forecasting model. The period from August 12–16, 2022, during a heatwave in Jiangsu Province, China, was selected as the weather background to simulate the impact of rooftop DPVs with varying power generation efficiencies on urban thermal environments and energy supply. The results indicate that (1) rooftop DPVs reduce urban air temperatures at 2 m by weakening the solar radiation reaching the surface. As solar panel efficiency improves, the cooling effects become more significant, particularly at night. Day and night air temperatures at 2 m can decrease by approximately 0.1 °C–0.4 °C and 0.2°C–0.7 °C, respectively; (2) Installing rooftop DPVs can lower boundary layer temperatures, with pronounced cooling effects during the day (up to 0.7 °C at 08:00) and night (up to 0.6 °C at 20:00); (3) If all buildings are equipped with rooftop DPVs, the electricity generated could meet Jiangsu Province’s total electricity demand during heatwaves. With 30% generation efficiency and rooftop DPVs installed at 40% of buildings, the electricity produced can meet the entire electricity demand.