Effect of the overhead height and tilt angle on comprehensive performance of photovoltaic roof based on simulation and experimental methods

• A simulation model and experimental system of a photovoltaic roof are established. • Effect of the overhead height and tilt angle on thermal and energy-saving performance of photovoltaic roof. • A simulation model is experimentally validated. • The comprehensive performances in a whole year were studied at different overhead heights and tilt angles. Photovoltaic utilization is a key strategy for advancing global carbon neutrality goals, as many countries strive to reduce greenhouse gas emissions. The integration of photovoltaic technology in buildings is becoming increasingly widespread across the world, with distributed photovoltaic systems, such as rooftop installations, demonstrating significant potential for development. However, there is relatively little research on the thermal and energy-saving benefits of photovoltaic roofs, especially regarding the influence of overhead height and tilt angle on thermal and electrical performance. Therefore, this paper established a simulated model to investigate the impact of various overhead heights and tilt angles of photovoltaic modules on thermal and electrical performance, as well as energy-saving benefits. Meanwhile, an experimental system was constructed to validate the model's accuracy, with the RMSE below 3.0 and the MAPE within 10 %. The results indicate that adjusting the overhead height slightly affects the daily cooling load difference between conventional and photovoltaic roofs, with negligible impact on overall energy-saving efficiency (less than 0.2 %). Notably, the power supply gain and comprehensive energy-saving efficiency of parallel overhead photovoltaic roofs are optimal in summer, with values of 307.2 W/m 2 and 18.8 %, respectively. However, the power supply gain and comprehensive energy-saving efficiency of parallel overhead photovoltaic roofs are the worst in winter. The optimal power supply gain and comprehensive energy-saving efficiency are achieved with a 20° tilt angle throughout the year, with values of 79.4 kW·h/m 2 and 25.5 %, respectively. As the tilt angle increases, the energy-saving performance decreases. The results of this paper can provide a reference for the design and optimization of photovoltaic roofs.