Sunshine-based global radiation models: A review and case study

Many empirical correlations and models have been developed to estimate solar radiation around the world. The most commonly used parameter for estimating global solar radiation is sunshine duration because it can be easily and reliably measured, and data are widely available. In this paper, we report the performance of 52 sunshine models for the estimation of the monthly mean global solar radiation on horizontal surfaces in Jouf, Saudi Arabia (29°47′N, 40°06′E, altitude 670 m). Some models are totally unsuitable for use in this region, and others vary in performance. The best models are identified.