1. A prediction system for predicting solar irradiance based on cloud characteristics, the system comprising: a sky imager comprising a customized lens configured to capture one or more substantially planar images of the sky; an image processor coupled to the sky imager and configured to process the one or more substantially planar images; a computing system coupled to the image processor and configured to: detect cloud characteristics based on the one or more substantially planar images, and predict the solar irradiance based on the cloud characteristics.