Modeling the Diffuse Part of the Global Solar Radiation in Algeria

The diffuse part of solar radiation is one of the elements necessary for the design and evaluation of energy production of a solar system. However, in most cases, when radiometric measurements are made, only global radiation is available. To remedy this situation, we present in this paper, an analysis of the scattered radiation measured on a horizontal surface for three sites in Algeria namely: Algiers, Tamanrasset and Bechar. We propose in this article models to determine the hourly ratio diffuse radiation / Global radiation received by a horizontal surface. The correlations established for the chosen sites were compared to the work of Liu and Jordan (1960), Orgill and Hollands (1977), Erbs et Al (1982), DT Reindl (1990) and Chendo (1994). The performances of our models were evaluated by conducting two statistical tests on the estimated diffuse fraction of solar radiation. The first test concerns the simplified comparison of the composite Residual Sum Squares (CRSS). In the second test, we calculate the mean absolute error (MAB). The new correlations presented in this study provide a significant improvement by reducing the standard error compared to existing models in the literature at a rate exceeding 40%. (C) 2012 Published by Elsevier Ltd. Selection and/or peer review under responsibility of The TerraGreen Society.