Photogrammetric point clouds for GIS-based high-resolution estimation of solar radiation for roof-top solar systems

Solar radiation is the main factor that must be considered when predicting solar systems energy output. Especially in built-up areas the use of Digital Surface Models (DSM) and analysis with Geographic Information Systems (GIS) has gained popularity for these predictions in recent years. However, the identification of small objects and their impact in the shadowing of solar systems is a very important factor that cannot be entirely acquired by models from common available Light Detection and Ranging (LiDAR) data. Thus higher resolutions DSMs are required. These can be generated from photogrammetric point clouds derived from Unmanned Aerial System (UAS) based large scale image flights. This paper presents a comparison between a common available resolution DSM generated from standardized LiDAR data and a DSM with very high resolution from photogrammetric point clouds. The added value of using high-resolution DSMs for solar radiation estimation for PV rooftop-systems is discussed with a focus on elevation, slope, aspect and on the suitability for selection of usable roof-top areas. Although DSMs with resolutions up to 1 cm have been generated, the results show that a DSM of 25 cm is enough for considering all small roof-top objects that are relevant for estimation of solar radiation.