Estimation of solar photovoltaic efficiency under the urban heat island effect

Onsite renewable energy supply is a crucial aspect of nearly zero-energy buildings (NZEBs). Understanding the amount and trend of potential electricity generation from local renewable sources is essential for planning and designing NZEBs. Given the urban heat island (UHI) effect, where temperatures are higher in urban areas than in less developed surroundings, the energy generated in urban areas may be lower than in rural areas as the conversion efficiency of solar cells decreases with increasing temperature. This research investigates the impact of the UHI effect on solar photovoltaic (PV) efficiency in densely built urban areas. The study integrates satellite-based solar irradiance data with local temperature measurements to account for thermal effects on PV efficiency. A random forest regressor was employed to model the nonlinear interactions between land cover variables—such as building density, vegetation, and road surface—and solar energy potential. Sensitivity analysis reveals that building height and density negatively affect solar energy generation. Notably, urban areas exhibit increased solar potential during winter as temperatures decrease. The findings underscore the importance of land composition in optimizing solar energy generation, with implications for promoting NZEBs in urban environments. This study offers insights into how urban morphology and regional climate variations influence solar efficiency.