New methodologies to estimate the hourly global solar radiation; Comparisons with existing models

This paper describes two new friendly and reliable approaches to estimate hourly global solar radiation on a horizontal surface even with a pocket calculator.Such fast and reliable predictions for the hourly solar radiation are necessary for the real-time management of both the solar energy sources, like a PV generator output in the one hand and the power loads, on the other.The predicted global solar hourly radiation values are compared with estimates from two existing packages and the recorded solar radiation for the two biggest cities of Greece.The two methodologies presented in this paper can be applied to any other site.