Evaluation of the Uncertainty in Accelerated Stress Testing

Within the photovoltaic standards community there is a desire to create a standardized set of tests suitable for predicting service life. Ideally, one would want to link a set of exposure conditions to an equivalent number of years in the desired use location, or to predict the performance as a function of time. However, the inherent uncertainties in the acceleration factors lead to large uncertainties in the results. Here we use literature values of the chemical degradation kinetics for some polymeric components, and extrapolate these to the field use. We show that without a well documented understanding of the degradation mechanisms, uncertainties in the kinetics lead to very large uncertainties in the prediction of field performance even when the general degradation factors are understood.