Irradiance calculation on shaded surfaces

Operating results of recently built photovoltaic systems have shown that shading can cause high losses in performance. We need methods for calculating the reduced irradiance to minimize the shading losses in the planning process. There are well-known models to estimate the irradiance received by a tilted surface. However, these methods normally do not include shading reduction caused by objects in the surroundings. Therefore, methods are proposed to include shading in calculations of direct and diffuse irradiation. Before these methods can be used, the surroundings have to be surveyed. Hence, how to survey objects in an easy way is discussed. Using the proposed methods and calculations it is possible to include shading reduction in the prediction of the irradiance on a tilted surface. Finally, the influence of shading on the irradiance is shown by an example. (C) 1998 Elsevier Science Ltd. All rights reserved.