Evaluation of sunshine and cloud cover based models for generating solar radiation data

Solar radiation models based on meteorological parameters serve as the substitute to measured irradiation and illuminance data. Models originating from sunshine or cloud cover information constitute the two main classes of meteorological radiation models. Further improvements in the accuracy of these models is under research. One such approach, attempted by Page, has resulted in the formation of a model that utilises a combination of the above mentioned variables. This article briefly discusses the new combined approach and evaluates it against other models developed by the authors: the Meteorological Radiation Model (MRM) based on sunshine fraction and the Cloud Cover Radiation Model (CRM) based on cloud cover. Results show that Page's approach is quite successful under overcast conditions. The MRM, however appears to provide better estimates under part clear and clear sky conditions