Characterizing (rating) the performance of large photovoltaic arrays for all operating conditions

A new method has been developed for characterizing the electrical performance of photovoltaic arrays. The method provides both a “rating” at standard reporting conditions and a rigorous yet straight-forward model for predicting array performance at all operating conditions. For the first time, the performance model handles the influences of irradiance, module temperature, solar spectrum, solar angle-of-incidence, and temperature coefficients, in a practical way. The validity of the procedure was confirmed during field testing of a 25-kW array installed by Arizona Public Service Company. This paper describes the characterization procedure, measured array performance, and the predictive model