Correlation Of Hourly Diffuse Fraction Of Global Horizontal Solar Radiation In Tamanrasset, Algeria

In order to evaluate the energy production of a solar system, the tilted global radiation is needed. Generally, only the global horizontal radiation data are available. To calculate a tilted global radiation, it is necessary to estimate the diffuse or the direct component of the horizontal solar radiation. In this article, a statistical procedure has been employed to develop correlations between the hourly measured of global radiation on horizontal surface and its diffuse component. In this context, the present work compares nine models for estimating diffuse fraction, using a 10 years data archive (1996-2005) of hourly global and diffuse solar radiation obtained at Tamanrasset meteorological station. After a first comparison of these nine models, three better performing models were selected for a more detailed analysis. The accuracy of the candidate correlations are performed in terms of the two widely used statistical indicators, MBE, RMSE and t-stat was also introduced. Thereby, new correlation coefficients are established taking into account the local data. The results suggest that some models can improve more accurately, by calibration procedure, the performance of the predictive models.