Determination of Direct Normal Solar Radiation From Measured Global Values—Comparison of Models

The modeling of direct normal solar radiation from measured global solar radiation is discussed and a new direct normal model developed from the Mississippi County Community College solar monitoring station at Blytheville, Ark., is presented. Comparisons of several existing models, including the Aerospace model developed by Randall and Whitson, are made. The Blytheville model and the Aerospace model are compared using five recent solar radiation data bases. The Aerospace model proved to be superior to all the models for the data bases used; however, the Blytheville model was only slightly less accurate and much easier to use. The Blytheville model predicted the beam radiation accurately for several widely varying climatic locations.