Abstract
An expert system is introduced for evaluating stand-alone photovoltaic system performance. Meteorological data, energy produced by the array, and the load profile serve as input for prediction of system performance. The expert system of data acquisition for real time supervision estimates how much energy cam be applied directly to the load. A method based on loss of load probability allows determination of the optimum combination of battery capacity and photovoltaic array peak power. An analysis conducted for a site in Algiers, Algeria, illustrates the method.