Performance impact of solar gain on photovoltaic inverters and utility-scale energy generation systems

Accurate performance and reliability evaluation of utility-scale photovoltaic (PV) systems requires accountability of solar gain contributions. A novel solar gain utility-scale inverter model has been developed to characterize inverter efficiency with respect to solar resource, general ambient conditions and thermal system losses. A sensitivity analysis was performed to evaluate the robustness of the model based on four assumed material properties. This analysis revealed 22.9% modeled internal inverter temperature sensitivity to surface absorptivity, with significantly less sensitivity to other parameters studied, indicating the impact of proper surface coating material selection on solar thermal absorption. This analysis was applied to a large utility-scale PV plant, assessing performance data from twelve 500kW inverters, and environmental data from twelve respective meteorological test stations. An RMSE value of 6.1% was found between the model and measured inner inverter temperatures. The results also suggest a negative 3.6×10-4 [W/m2]-1 normalized inverter efficiency correspondence with solar gain heat adsorption across the twelve inverters for a one-day, clear-sky time period.