Methods for high-voltage bias testing of PV modules in hot and humid climate

Abstract

The accelerated tests currently carried out on PV modules reduce the infant mortality as well as improve the production techniques during the manufacture of PV modules. However, the accelerated tests do not completely duplicate the real world operating conditions of PV modules. Hence it is essential to deploy PV modules in the field for extended periods in order to estimate the degradation, if any, as well as to elucidate the degradation mechanisms. Moreover, PV modules should be tested by specially designed tests in harsh climates. At Florida Solar Energy Center (FSEC) high-voltage bias testing of PV modules was carried out in hot and humid climate with the individual modules biased at +/- 600 V. It was observed that the leakage currents flowing from the PV circuit to the ground is directly proportional to the bias voltage. PV systems with maximum voltage of 1000 V are installed in Europe and elsewhere which means higher leakage currents will be produced in the PV modules. Based on this fact and the earlier observations, high voltage bias testing of c-Si PV modules specially designed for high voltage operation was carried out in hot and humid climate with the individual modules biased at +/-1500 V at FSEC and higher. This paper provides results of high voltage bias testing of PV modules. The results indicate that the test can be considered as reliable metric in determination of the long term performance of PV modules.