Estimation of the Diffused Solar Irradiation on the Tilted Plane of Photovoltaic Solar Panels

Solar energy, in the recent decades has gained a great attention due to its clean, simple and easy adaptable process. The effective utilization of solar energy is possible only if proper data of incident solar radiation is available. There are number of solar models based on different climatical factors, for the assessment of radiation on plane and sloped surfaces are available in the literature but the selection of best possible model is a challenging task. Here, different isotropic and anisotropic solar models have been utilized for the estimation of overall radiation incident on the sloped surface in Karachi then estimation was compared with the experimental values. The models selected for this study includes Liu and Jordan, Koronakis, Badescue, Hay and Davies, Temps and Coulson and HDKR. The predicted values and measured values are compared by using different statistical techniques like Mean Absolute Percentage Error (MAPE), Mean Biased Error (MBE), Root Mean Square Error (RMSE) and t-stats. The outcomes revealed that isotropic models are more suitable model than the anisotropic models. Among all models, Badescue is the best suitable model for the estimation of radiations on sloped surfaces with lowest value of MBE, RMSE and t-stats while Temps and Coulson model, on the basis of MAPE, MBE, RMSE and t-stats is the most inappropriate correlation for the assessment of solar radiations on sloped surface. Overall, for the solar radiation estimation on any sloped plane in Karachi isotropic models have shown a good agreement.