Development of weighted efficiency for photovoltaic inverters: A Brazilian case study

A limitation of current weighted efficiency ratings for photovoltaic (PV) inverters is that their weighting coefficients are specific to certain climates and may not represent other regions. This challenge has become more relevant with the expansion of PV deployment and the growing number of commercial inverter brands and models competing in the market, increasing the need for fair comparative evaluation and performance oriented selection. Widely used weighted efficiency ratings, such as the European weighted efficiency (EURO) and the California Energy Commission (CEC) weighted efficiency, combine laboratory measured efficiency points with weighting coefficients derived from historical irradiance distributions that reflect their reference locations rather than all climates. This paper derives Brazilian weighting coefficients from high resolution, long term irradiance data and quantifies their implications for weighted efficiency ratings relative to the EURO and CEC metrics. The database comprises 10 years of 5 min irradiance data from 137 Brazilian cities. Statistical analyses are used to assess the similarity between state, regional, and national weighting coefficients, establishing a nationally representative set for practical use. The proposed coefficients are experimentally supported by controlled laboratory tests on eight commercial PV inverters performed under standardized conditions. Furthermore, a load reduction strategy is proposed, reducing the test time required for weighted efficiency measurements by 50%, with a maximum deviation of 0.09% relative to the full set of load points for the evaluated inverter class. • Proposal of a methodology for weighted efficiency of photovoltaic inverters. • Climate representative efficiency rating proposed for photovoltaic inverters in Brazil. • Analysis of irradiance data from 137 Brazilian cities over a 10-year period. • Reduction of inverter testing time by 50% with a maximum difference of 0.09% in results.