Comparison of solar irradiation models in an urban context with Shanghai climate

This work presents a comparative study of three approaches for predicting surface irradiation in the urban context due to the sky radiation. The main goal is to quantify the effect of the amount of nearby obstructions. For this purpose, two test scenes are generated. The first scene corresponds to an unobstructed inclined surface. The second scene corresponds to an urban canyon. The three most representative approaches to treat the sky diffuse radiation, i.e.: isotropic, anisotropic and radiance distribution within the sky vault, are tested in each scene. In the case of unobstructed surfaces, the anisotropic model gives similar results (± 4 %) compared with the radiance distribution method, which has a more rigorous treatment of the sky radiation anisotropy. On the other hand, significant differences are reported between these two models when dealing with obstructed scenes.