Prediction of diffuse radiation in solar energy applications: Turkey case study and compare with satellite data

Abstract

In solar engineering applications, the components of the solar radiation a location must be known to design the systems. Due to the difficulties in the diffuse solar radiation (DSR) measurements, as this component has not been measured in everyplace, the DSR models have been established for various locations over the world. In this study, the models developed to constitute a relation between the monthly mean daily diffuse fraction and diffuse coefficient with clearness index and sunshine fraction in the open literature for Turkey are reviewed. In addition, the comparisons of the DSR values taken from the NASA – Surface meteorology and Solar Energy (NASA-SSE) and computed from the best models for example two cities are carried out. The performances of the models are investigated by various statistical test techniques. These statistical test techniques are root mean square error (RMSE) and mean absolute error (MAE). The statistical comparisons show that the best models give well agreement with the DSR values taken from the NASA-SSE. The difference between the yearly total DSR calculated from the best models and NASA-SSE is approximately 1.94% for Erzurum and 0.57% for Gebze.