The Effect of Walls on the Sky View Factors of Photovoltaic Systems

Photovoltaic collectors deployed in multiple rows and near the structure’s walls are obscured from the receiving part of the diffuse skylight. Obscuring part of the diffuse skylight to the collectors decreases the incident diffuse radiation and thus, results in diffuse radiation losses. These losses are associated with the sky view factors. The inter-row diffuse radiation losses are associated with the sky view factor of the collector, and the wall diffuse radiation losses are associated with the sky view factor caused by the wall. The purpose of the present study is to develop mathematical expressions and a methodology for sky view factors of PV systems installed near obscuring walls. The study investigates the effect of the wall height, distance of the wall to the collectors, and collector and wall azimuth angles, on the sky view factors. The study may assist the PV system designer in assessing the contribution of the incident diffuse radiation to the generated electric energy of PV systems installed near obscuring walls. The simulation results indicate that the overall range of the sky view factor variation may be quite noticeable, between 0.97 (without the presence of a wall) and 0.78 (with the presence of a wall), for the parameters used in the study.