An adaptive method to derive direct irradiance from global irradiance

摘要: Observations and estimations of solar radiation at ground level deal most frequently with global horizontal irradiance (GHI) while direct is crucial notably for Concentrated Solar Technology (CST) such as energy conversion systems: parabolic through, towers, dish or concentrated photovoltaic. Several global-to-direct schemes are proposed in the literature. They obtained by regression an empirical parametric function measurements made few stations over a time period. These well suited to climatic region where they have been designed, but not likely other regions. A new method proposed. general shape relationship between clearsky index (Kc) ratio diffuse (fD) derived from literature analysis several data sets measurements. This analytical needs two parameters. One defined case overcast skies; changing depending on clear-sky conditions location under concern. model provides Kc fD conditions. The was validated against BSRN located Carpentras, Sede Boqer Tamanrasset. It reveals itself accurate compared methods. Indeed, used, bias amounts 0%, -9% 10%, root mean square deviation (RMSD) 16%, 19% 21% correlation coefficient 0.98, 0.96 0.95. interesting because it flexible, adaptive does rely parameter.