Analysis of statistical methods for estimating solar radiation

Abstract

Daily global radiation is not only required for a large number of ecological, physiological and agro-meteorological models but also is required for the design and evaluation of solar energy systems. Global radiation data is quite frequently not available for all locations. For such locations daily global radiation can be estimated statistically using continuous series of other measurable meteorological parameters. This paper considers four statistical methods for estimating the daily global radiation: Angstrom-Prescott, Coulsen, Hargreaves and Supit-van Kapel method. The empirical coefficients that characterize these methods were determined using the least squares method for the two locations near Belgrade in Serbia. The results showed that calculated empirical coefficients are similar to values that were previously determined in similar researches for neighboring countries. Further analysis verified accuracy and applicability of four empirical relations, where Ǻngstrom-Prescott and Supit-Van Kappel methods proved to be by far the most reliable in the assessment of daily global radiation.