A PERFORMANCE PREDICTION METHOD FOR SOLAR-ENERGY SYSTEMS

Recent studies of solar radiation have shown that instantaneous solar radiation exhibits a distinct bimodal character associated with clear and cloudy states. This suggests that many solar systems may simply be modelled to operate in an on/off fashion corresponding to clear/cloud y time intervals. It is shown that the average-daily solar system perf ormance may be calculated from the product of clear-sky solar performa nce and the average time fraction of clear sky. This approximation gre atly simplifies the solar system performance prediction. The proposed method is verified with a solar hot water system. The predicted result s compare favourably with results predicted by the phi-fBAR chart meth od and give a conservative estimate of the experimentally measured per formance.