Performance and reliability of a 15 kWp amorphous silicon photovoltaic system

Florida Power Corporation, in cooperation with the Florida Solar Energy Center, has installed a 15 kWp grid-connected photovoltaic system at one of its substations near Orlando, FL. The system utilizes thin-film amorphous silicon modules and was installed in August 1988. The system´s performance has been monitored for 20 months of operation, and periodic diagnostic tests to evaluate subsystem reliability have been conducted. During the 20-month period, the power output of the photovoltaic array has degraded by about 25% of its original value and the array peak power efficiency was 4.0% in April 1990. Relatively high leakage currents of the photovoltaic array, particularly under wet conditions, have been detected. A significant corrosion build-up on 23 out of a total of 640 photovoltaic modules has also been observed in the 20-month period