Ever wondered how much solar power you can tap from your roof? Rooftop solar panels are gaining in popularity, but not all property owners realize the impact of site-specific conditions on the efficiency of solar cells.
Scientists from the University of Gothenburg have created a tool that calculates the maximum magnitude of solar incidence, meaning the time of sunlight exposure and time spent in shadow. People can use the tool to determine the difference between rooftop solar and ground-mounted solar panels. From there, a cost-comparison can help them decide whether to install solar and, if so – where?
Solar incidence is reduced by obstacles between sunlight and the panels themselves. These include overhanging vegetation and nearby tall buildings. In addition, rays of sunlight need to strike rooftops at an optimal angle in order to most efficiently generate power.
The new solar calculator tool uses computer-based geographical information systems (GIS) to collect, store, and analyze geographical data. A model showing 3-D surroundings of a rooftop shows how shadows may impact solar panels installed on a roof. From there, you can calculate how much solar power can be generated.
Of course, the shadow effect will change over the course of a year, throughout the seasons. The new tool can show total solar radiation on every part of a rooftop for each month, or over an entire year, calculated in kilowatt hours (kWh) per square meter.
The solar energy project has been carried out by the University of Gothenburg in collaboration with WSP Analys & Strategi, and it has just presented its final report. The project has been financed by the SolEl programme, the Research Foundation of Göteborg Energi, the City Planning Administration of Gothenburg and the Region Västra Götaland County Council.