Worldwide Lifetime Prediction of c-Si Modules Due to Finger Corrosion: A Phenomenological Approach

Lifetime prediction of solar modules based on laboratory qualification results and location-specific weather data has been a pivotal research problem in the photovoltaic community. Data analytic techniques (e.g., performance loss rate method, statistical clear sky model, Suns-Vmp methods) quantify the integrated degradation from measured data of a solar farm; however, the nonlinear time-dependence of individual degradation and correlation among the degradation modes make it difficult to use the experimentally obtained integrated degradation rates for ultimate lifetime projection. In this article, we use a well-documented, experimentally-validated, and physics-guided empirical (sigmoidal) model to predict c-Si solar module failure caused by temperature and moisture-enhanced contact corrosion. The degradation parameters are obtained from damp-heat qualification tests and the worldwide weather data from NASA/NSRDB databases. Taken together, the model predicts the location-specific power loss and the lifetime of a module exclusively because of contact corrosion. Our results show that a combination of high relative humidity and temperature is needed for higher corrosion; in fact, any decrease in relative humidity increases the lifetime significantly. This model serves as one component of a PV reliability framework that will predict the lifetime of a module that is under various and/or correlated degradation mechanisms including solder bond failure, yellowing, and potential-induced degradations.