Extracting sky feature information effecting solar irradiance during sun occlusion events

Abstract

Accuracy under partly cloudy conditions has been an issue in most previous studies of solar irradiance estimation and prediction. Under the conditions, sun occlusion events (SunOE) occur frequently. During SunOEs, not only solar irradiance was attenuated, but also cloud enhancement events occurred. In this experiment, 29% of SunOEs was enhanced. In 92% of enhancement cases, lens flares were observed in the camera images. Sky feature information was extracted in each image from six areas assumed to affect to solar irradiance. Using MLP, effective factors were found, the lens flare, the area of high-luminosity and thin cloud component.