High-voltage bias testing of thin-film PV modules

Grid-connected PV systems must withstand high voltage bias in addition to harsh environmental conditions. High leakage currents can lead to electromigration and degradation, and thus become important issues for reliability and safety. This paper describes high voltage bias testing of thin-film PV modules in hot and humid conditions in Florida. Sudden rise in RH caused by sudden drop in temperature during the day resulted in sharp peaks in leakage current. Leakage currents for a typical clear sunny day in summer were approximately double compared to corresponding values in winter. Low-resistance paths created with the passage of time increased the leakage current continuously indicating probable exponential growth in leakage currents. Leakage currents increased proportionately to applied voltage bias, at least up to 600 V, showing potential of the technique as an excellent acceleration test.