Abstract

This paper presents hourly solar radiation estimation methods using ambient temperature and relative humidity data. The methods are based on the decomposition model that is calculating each of solar radiation components, which depend on atmospheric transmittance. Two methods to predict atmospheric transmittance value using available meteorological data were proposed. In the first method, a decision matrix was used, while in the second method, regression correlation of meteorological parameters was used. The calculations results were evaluated using statistical parameter. Though the result shows both of the methods perform well, more satisfactory results were obtained from first method with Root Mean Square Error of 87.6 Watt/m2, Normalized Root Mean Square Error of 8.29%, correlation coefficient of 0.95 and index of agreement of 0.97. Furthermore, the first method only needs ambient temperature and relative humidity data that commonly measured in meteorological stations.