Field Investigations of Potential-Induced Degradation (PID) for Crystalline Silicon PV Panels in Different Climates

The relationship between field performance and indoor chamber measurement for potential-induced degradation in crystalline silicon PV modules is still unclear. Many acceleration models have been proposed but without strong evidence from field experiments. Our approach focuses on building field testing systems under three different climates: tropical, subtropical, and mountain climates in Singapore, Changzhou (China) and Golden (CO, USA) respectively, in a collaborative testing campaign involving Trina, SERIS and NREL. Each testing system has six groups of modules developed by Trina Solar with different grades of PID resistance from weak to strong. The objective of this 3-year project is to build up the correlation between the outdoors behaviors to chamber tests, and deduce a climate-specific degradation model. A degradation of up to 23% was observed after 18 weeks for the most PIDsusceptible module was found in Singapore. Activation energy of 0.94-1.1eV and 0.55-0.63eV were determined for wet and dry conditions, respectively, by fitting the leakage current data in Singapore and in Golden, and an exponential decay of degradation was shown as a function of accumulated charge.