On the random nature of solar radiation

The correlation of beam and global radiation is examined on an hourly, monthly and yearly basis from analysis of nearly 3000 days of simultaneous hourly horizontal global and normal beam radiation measurements for Bet Dagan, Israel. One-to-one beam-global correlations are obtained by appropriately averaging over the correlation matrices, and these results are compared with the corresponding correlation functions that are based on U.S. radiation data. The accuracy of predicting yearly collectible energy for solar collector systems from hourly global data plus an hourly beam-global correlation function is determined in a form whose results may be of more general value than could be obtained with computer simulations.