Synergistic cooling and energy gains of photovoltaic green roofs for sustainable cities

Urban photovoltaic (PV) deployment is expanding rapidly as a cornerstone of global decarbonization, yet its unintended side effect, the photovoltaic heat island (PVHI), poses emerging risks to urban microclimates, public health, and community acceptance. Green roof has the potential to mitigate urban heat islands, however, current research rarely accounts for the dynamic interactions between PV arrays and green roofs. This study developed a high-resolution bidirectional feedback framework to evaluate photovoltaic green roofs (PVGR) and introduced a new power generation cooling index (Iδ‐E) to unify energy yield and thermal regulation, thereby enabling further optimization of PVGR parameters including photovoltaic layout and plant configuration. Results revealed that conventional PV arrays elevated air temperature by 0.2–0.9 °C, whereas PVGR reduced it by 1.8–2.9 °C relative to PV alone. Waste heat from PV modules enhanced plant transpiration by 23.3–28.7 W/m3, producing a synergistic cooling benefit and modestly boosting PV efficiency. Optimal configuration (PV vertical distance from plant 1.3 m, row spacing 1.2 m, tilt angle 25°, coverage 20 %; plant height 1 m, leaf area density 1.5 m2/m3) maximized combined performance. These findings provide scalable design principles to balance renewable energy expansion with urban heat adaptation, bridging the gap between clean energy deployment, urban climate adaptation, and public acceptance.