Performance variation of commercially available modules after six months of outdoor system voltage stress testing

System voltage stress has been shown to cause performance degradation in PV modules. This effect has been most prevalent in hot and humid climates such as Florida. Several modules from leading manufacturers have been deployed at the Florida Solar Energy Center for outdoor high voltage bias testing. Following a period of six months of continuous application of negative 600 V, performance analysis has been carried out. A large variation in the performance of different module types was observed. Characterizations included illuminated current-voltage, dark current-voltage, and electroluminescence imaging. A statistical analysis was performed on the performance data to determine the extent and variation of system voltage induced degradation in commercially available modules of similar cost and construction.