Diffuse irradiance on tilted planes in urban environments: Evaluation of models modified with sky and circumsolar view factors

Numerous studies have analyzed existing irradiance models for estimating sky diffuse on tilted planes. However, few evaluated the suitability of these in obstructed environments, specifically considering effects obstacles. In this study, three —one them with five variants— planes located urban environments were evaluated. All been adapted to consider effect an canyon received a plane through view factor and circumsolar factor. against values obtained by ISO 15469:2004(E)/CIE S 011/E:2003 angular distribution model. Therefore, it was necessary determine standard type corresponding each record measurements performed scanner at radiometric station UPNA (Spain). A total 4,864 scenarios considered occur from combination different orientations inclinations plane, aspect ratios canyon. The results revealed that Perez model 35° half-angle region has best performance, followed 45° region.