Thermal and Electrical Performance of Photovoltaic Modules Installed Above Green and Asphalt Roofs Under Real Operating Conditions

Photovoltaic (PV) systems integrated with green roofs have attracted increasing research interest due to their potential influence on rooftop microclimatic conditions and photovoltaic operating performance. This study experimentally investigated the thermal and electrical behavior of two identical PV modules installed above green and asphalt roof surfaces under real operating conditions in a Central European climate. Rear-side module temperatures and meteorological parameters were monitored, while electrical performance was evaluated using on-site I–V curve measurements. The observed rear-side temperature differences ranged from 0.01 °C to 0.86 °C during the monitored short-term summer periods. A representative I–V measurement indicated approximately 13% higher instantaneous maximum power output for the PV module installed above the green roof configuration under comparable operating conditions. However, the electrical results should be interpreted cautiously due to short-term environmental variability and irradiance-related uncertainty during consecutive field measurements. The presented results correspond to a short-term summer field-monitoring study and should not be generalized to annual photovoltaic performance without extended long-term multi-season experimental validation. The scientific contribution of this study lies in the synchronized side-by-side evaluation of identical PV modules using combined rear-side thermal monitoring and in-situ electrical characterization under real operating conditions.