Thermal and Radiative Properties of Photovoltaic, Artificial and Natural Land Covers to Support Urban Planning

The growing population is leading to an increase in urban areas and energy consumption. This replacement of natural areas by impervious surfaces increases the local land surface temperature (LST) producing an urban heat island (UHI). Photovoltaic solar panels (PVSP) provide renewable energy to the cities, but their impact in the UHI is unclear. This study uses aerial images collected over Lucca, Italy, with high-spatial and -spectral resolution in the thermal and the 400 - 2500 nm spectral domain to understand the impact of PVSP on the UHI. For that purpose, a) a land cover map displaying PVSPs, roof materials, roads and agricultural and natural covers was developed to analyze the LST and albedo of each class, and b) different scenarios were built to calculate the variation in LST and albedo if placing PVSPs over each class. The results highlighted the importance of the natural areas to reduce LST and showed that placing PVSPs over most roof materials mitigates UHI, except for white painted concrete roofs and black clay tiles roofs. The LST and albedo of the roofs changed with the color and material, reaching differences up to 14 °K and albedo variations between 0.12 and 0.49. The highest LST was obtained by dark and red metal roofs, with LST > 10 °K than PVSPs. This study demonstrated that the effect of PVSPs on UHI depends on the roof material where they are placed on, and validated the use of aerial images to support urban planners to mitigate UHI.