Capacity Factor Analysis of U.S. PV System Reliability and Performance

We present an evaluation of the ac capacity factor to estimate the reliability and performance trends of existing plants in the United States. The capacity factor is a metric that is widely used in the electrical power sector to estimate operational consistency. We show that the ac capacity factor provides useful insight to assess the system productivity. We analyze U.S. Energy Information Administration data for more than 2300 plants, showing that both ac capacity factor and inverter-loading ratios have increased in recent years, and that the capacity factor tends to increase for larger systems and increases as would be expected for mounting configurations and locations associated with high insolation. Evaluation of the data for reliable (consistent) performance concludes that inconsistent operation causes much more variation in reported electricity generation than linear degradation.