High performance ratios of a double-junction a-Si BIPV grid-connected installation after five years of continuous operation in Brazil

In September 1997 LABSOLAR, at Universidade Federal de Santa Catarina, installed the first grid-connected, thin-film, building-integrated PV system in Brazil. In this fully monitored installation, irradiation levels, temperatures and electrical performance data are measured and logged continuously. The AC and DC performance ratios (PR=ratio of actual to expected output) of this 2 kWp double-junction a-Si PV system after over five years of continuous operation have stabilized at an average of 82% and 92% respectively, with annual energy yields of /spl sim/1300 kWh/kWp for a /spl sim/1500 kWh/m/sup 2/ annual plane-of-array radiation level at the site. Our results show that in the stabilized state the PR is independent of the cell operating temperature, indicating a negligible temperature coefficient of power and good performance when operated at a warm site. Under the conditions described, undersizing the inverter with respect to the PV array power might lead to considerable power losses.