Regional variations of days of autonomy for solar energy applications

A problem faced by designers of stand-alone solar installations is the sizing of the collector area and storage capacity. From a curve of the minimum possible insolation over any period of days for a given site, a functional relationship between the collector-area and storage-capacity that provides a 0% probability of not meeting load (PNML) can be derived. This permits evaluating the regional variations in days-of-autonomy required to provide 100% reliability. Such variations are shown for Texas based on recent insolation data.