Boosting bifacial rooftop PV Performance via optical–electrical–thermal optimization of radiative cooling and green roofs

While rooftop photovoltaics (PV) are pivotal for decarbonizing buildings, the energy interplay between bifacial PV systems and underlying roof materials, especially regarding their combined impact on building energy consumption and power generation across diverse climates, remains insufficiently explored. This study proposes an integrated optical-electrical-thermal modeling framework to evaluate bifacial PV systems on bare, radiative cooling, and green roofs across China. Results reveal that radiative cooling roofs achieve the highest annual PV power generation (up to 144.65 kWh/m2), enhancing output by 20–30% compared to bare roofs, while green roofs most effectively reduce heating, ventilation, and air conditioning (HVAC) energy consumption in most eastern regions. The comprehensive performance metric PV satisfaction rate for HVAC load (PSR-HVAC), shows that radiative coolers and green roofs can achieve near or full HVAC energy independence (up to 120%) in hot summer and warm winter regions and temperate regions, whereas conventional bare roofs peak at only 105.3%. This study provides architects and engineers with a validated decision-support tool for selecting regionally suitable roof-PV combinations, while offering policymakers science-based references for developing localized building energy codes.