Generalized capacity factors for grid-intertie solar photovoltaic systems

We present a simple calculation and graphical procedure for direct determination of the annual capacity factor of no-storage grid-interie photovoltaic systems. This is applicable to the principal solar collector types and to a wide range of climates. This method provides "translation equations" for predicting both instantaneous power output (under any specified test conditions) and long-term average power output of photovoltaic modules from instantaneous measurements. Such a procedure, which we validate for one site only, should enable a designer to make accurate preliminary assessments concerning the suitability of potential sites and solar collector types by simple analytic calculations or, equivalent, by reading poinst off the graphs presented herein.