Comparison of Rooftop and Façade Photovoltaics: Impacts on thermal-electrical performance and indoor environment for achieving zero-carbon targets through simulation and experiment

The application of photovoltaic modules is crucial for achieving energy transition and climate goals. However, due to the complexity of the dynamic energy-heat balance process in photovoltaic modules, the parametric study of their electrical and thermal performances must account for their inherent synergistic effects rather than examining them in isolation. The study developed thermoelectric coupled heat transfer models of different photovoltaic module forms (rooftop and façade photovoltaics) through a combination of experimental and simulation approaches in a representative region of Beijing. The impact on thermoelectric performance, energy savings, and thermal comfort were analyzed in depth. The results indicated that rooftop photovoltaics exhibited significant advantages in solar shading, thermal insulation, and electrical performance. Specifically, compared to the buildings without photovoltaics, it reduced peak temperature by 12.42 °C, delayed peak temperature occurrence by 2.4 h, and decreased the cooling load by at least 69.6 %.Temperature fluctuations and climatic factors exhibited a “game” phenomenon, affecting power generation performance. Rooftop photovoltaics mitigated the negative effects of temperature rise while improving power generation performance, resulting in the average power increase of 53W, an extended peak power duration by 2 h, and an overall power generation yield improvement of 25 %. Additionally, the photovoltaics module minimized the direct impact of climatic factors on the indoor thermal environment through its thermal hysteresis effect, thereby enhancing indoor thermal comfort. Moreover, taking into account the synergistic energy saving benefits of shading effect and power generation efficiency, the overall energy saving potential of rooftop photovoltaics was increased by at least 63.5 %. The inherent limitations of thermal property improvement of the exterior building surfaces were effectively compensated by the improvement in electrical performance. This study provided theoretical support for photovoltaics integrated buildings to achieve a dynamic balance between energy supply and demand and energy saving development in the practical operation.