Solar panel suitability map and assessment of the location of installed panels in roofs in the municipality of Vitoria-Gasteiz (Alava, Spain)

Abstract

Dependency on unsustainable energy sources like fossil fuels is at the stake due to their contribution to global warming and climate change. The pursue of development and exploitation of alternative, cost-effective and environmentally friendly energy sources like renewables energies is vital for the reduction of greenhouse emissions to the atmosphere. Solar energy is a freely available renewable energy with great potential and comparatively free of CO2 emissions. This work focuses on the installed solar capacity in Vitoria-Gasteiz, a medium-sized city of about 250,000 inhabitants in the Basque Country, north of Spain. A roof suitability map has been produced using a potential solar radiation algorithm together with a highly resolved 1m Digital Surface Model (DSM) derived from LiDAR data. Location and orientation of solar panels on roofs of city buildings have been manually digitized from ortophotos, which resulted in 1,349 photovoltaic solar panels polygons on 183 buildings and a total horizontally projected surface of 22,253 m2. By comparing the radiation impinged on the area covered by the PV panels with the potential energy of the whole roof area, a usability rate was calculated and 49 installations found to be located in unsuitable locations. The findings identify a considerable number of installations for which the efficiency of the installation is low but could be easily improved by simply relocating the panels in a more suitable fashion in the same building.