|Jordan, D.; Kurtz, S.|
This paper presents performance data from nearly 50,000 Photovoltaic systems totaling 1.7 Gigawatts installed capacity in the USA from 2009 to 2012. 90% of the systems performed to within 10% or better of expected performance. Only 2-4% of the data indicate issues significantly affecting the system performance. Special causes of underperformance and their impacts are delineated by reliability category. Delays and interconnections dominate project-related issues particularly in the first year, but total less than 0.5% of all systems. Hardware-related issues are dominated by inverter problems totaling less than 0.4% and underperforming modules to less than 0.1%.