Synergistic effects of elevated photovoltaic-green roof canopy systems on microclimate regulation and power generation efficiency: a comparative experimental study

Urban rooftops represent an underutilized spatial resource with significant potential to facilitate renewable energy development. This study investigates the synergistic mechanisms between elevated photovoltaic (PV) canopies and green roofs through comparative field measurements across six representative configurations. The results demonstrate that the elevated PV-green roof canopy (Case 3) exhibits better performance in both microclimate regulation and energy efficiency. For thermal comfort, Case 3 consistently reduced the maximum air temperature at the pedestrian level by an observed range of 1.73–2.56 °C compared to the bare roof (Case 0) throughout the experimental period. It demonstrated a stable cooling trend under both clear and partly cloudy conditions. Notably, during active hours (08:00–20:00), the system modulated average wind speeds to a thermally comfortable range of 0.358–0.455 m/s. For energy performance, the daily power generation of Case 3 increased by 5.47%–9.27% compared to the standalone elevated PV canopy (Case 2), which is primarily attributed to the evaporative cooling effect of the vegetation. Consequently, this system achieves a synergistic enhancement of the “Energy-Ecology-Activity” framework, providing a scientific basis for sustainable rooftop retrofitting in high-density urban environments.