STATISTICAL COMPARISON OF SOLAR-RADIATION CORRELATIONS - MONTHLY AVERAGE GLOBAL AND DIFFUSE-RADIATION ON HORIZONTAL SURFACES

For most solar energy applications, it is necessary to predict the amount of global and diffuse radiation arriving on a horizontal surface at any specified location. Scientists have developed methods to achieve this using different input parameters. The purpose of this study is to compare statistically correlations for estimating the monthly average daily global/diffuse radiation incident on a horizontal surface and to recommend one in each category that best fits measured data from a number of locations chosen and is the simplest to use. The effects of using the new solar constant of 1367 W** minus **2 in these correlations are also investigated. As a result, Rietveld's and Page's correlations are recommended for estimating monthly average daily global and diffuse radiation incident on a horizontal surface, respectively. In addition, these correlations seem to be just as accurate with the new solar constant.