Forecasting Diffuse Solar Irradiation
Abstract
The majority of research into predicting diffuse solar irradiation has been conducted using contemporaneous values of the clearness index augmented by other predictors. In recent years this research has largely been developed using variants of the Boland-Ridley-Lauret decaying logistic function model. The focus on developing models for prediction of diffuse (or direct) irradiation starting with global horizontal irradiation (GHI) is due to the ease of measuring GHI (or estimating it from satellite images) as compared to the complicated and expensive means of measuring diffuse and direct. Little attention has been directed at developing methods of forecasting diffuse irradiation from previous values of it of clearness index. One approach is given in this paper and alternative approaches will be proposed.
Keywords
Diffuse solar irradiation, global solar irradiation (GHI), forecasting, clearness index, diffuse fraction.