%0 Journal Article
%T A Comparative Study of Some Regression Models to Estimate the Global Solar Radiation on a Horizontal Surface from Sunshine Duration and Meteorological Parameters for Gharda£ża Site, Algeria
%A Kacem Gairaa
%A Yahia Bakelli
%J ISRN Renewable Energy
%D 2013
%R 10.1155/2013/754956
%X A comparison between some regression correlations for predicting the global solar radiation received on a horizontal plane has been processed. Seven models for estimating the global solar radiation from sunshine duration and two meteorological parameters (air temperature and relative humidity) are presented. The root mean square error (RMSE), mean bias error (MBE), correlation coefficient (CC), and percentage error ( ) have been also computed to test the accuracy of the proposed models. Comparisons between the measured and the calculated values have been made. The results obtained show that the linear and quadratic models are the most suitable for estimating the global solar radiation from sunshine duration, and for the models based on meteorological parameters, Abdalla and Ojosu's models give the best performance with a CC of 0.898 and 0.892, respectively. 1. Introduction Solar energy applications require a complete knowledge and detailed analysis about the potential of the site, so a database at ground level is an important feature of solar energy systems. Measurements of global solar radiation reaching the surface of the earth and its two components direct and diffuse are essential in the most research fields of solar energy. The daily values as well as the monthly ones are needed to evaluate the performance of existing solar devices and estimate the efficiency of the future installations [1, 2]. When the site under consideration is equipped with a radiometric station operates regularly for several years, it will be easier to exploit solar energy resource. However, in most cases, there are no local measurements and we must resort to approximate methods to predict the characteristics of solar radiation. In order to estimate the amount of solar energy incident on a horizontal surface, many models have been developed which relate the global solar radiation (H) with the sunshine duration. The first one is that proposed by Angstrom [3¨C5] which predicts the monthly average daily global solar radiation from sunshine duration and clear sky radiation data. Prescott puts this equation in a more convenient form, replacing the clear sky radiation by the extraterrestrial one [6]. Then, the Angstrom-Prescott model was developed by many researchers, who have correlated the global solar radiation with the sunshine duration in another regression forms [7¨C22] and with some meteorological parameters such as air temperature, relative humidity, cloudiness, and wind velocity [23¨C34]. Each of these factors contributes in a significant manner in the estimation of global
%U http://www.hindawi.com/journals/isrn.renewable.energy/2013/754956/