The effect of uncertainty in modeling coefficients used to predict energy production using the Sandia Array Performance Model

Predicting photovoltaic array performance is an important part of system design and monitoring, so it´s important to quantify the uncertainty associated with the predictions. The Sandia Array Performance Model is one of many tools used to predict annual energy production, but the effect of the uncertainty in model coefficients has not been fully investigated. This paper quantifies the relative importance of voltage and current temperature coefficients, as well as the coefficients relating voltage and current to solar irradiance, for crystalline silicon modules. Using the coefficient variation observed in the Sandia module database and computer simulation, the effect of the uncertainty was quantified in terms of the range in predicted annual energy production relative to actual energy production by three small grid-connected PV systems. The relative importance of each coefficient by month of the year was also determined in order to understand the seasonal behavior of the performance model.