Estimating loss-of-power probabilities of stand-alone photovoltaic solar energy systems

Abstract This paper describes an approximate approach to evaluating the performance, including the probability of loss-of-power (or loss-of-load, as some would have it) of stand-alone photovoltaic solar energy systems. The method treats the energy capture, storage and disbursement process as a random walk in the storage domain. To apply the technique, one must know the variance, as well as the mean, of the probability density of the daily solar insolation impinging onto the photovoltaic array. Analytical expressions are obtained for the probability of depleting the system's storage, as well as how much auxiliary energy, on the average, would be required to cover the load in that event.