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

• Published in: Renewable energy 2021-12, Vol.180, p.1194-1209, Article 1194
• Main Authors: García, Ignacio, de Blas, Marian, Hernández, Begoña, Sáenz, Carlos, Torres, José Luis
• Format: Article
• Language: English
• Subjects: Diffuse solar irradiance; Tilted planes; Urban canyon; Urban environments
• ISSN: 0960-1481; 1879-0682; 1879-0682
• DOI: 10.1016/j.renene.2021.08.042

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