- New Brazilian weighting coefficients enable more accurate evaluation of photovoltaic inverter performance across the country.
- Laboratory tests confirm the metric closely aligns with established European and Californian standards while reducing testing time by 50%.
- The approach supports streamlined benchmarking and could guide future efficiency testing for larger inverters and diverse operating conditions.
Brazilian researchers have developed a national weighted efficiency metric for photovoltaic inverters, addressing a key limitation of existing ratings that rely on regional irradiance patterns. Conventional metrics such as the European weighted efficiency (EURO) and California Energy Commission (CEC) efficiency combine laboratory efficiency measurements with weighting coefficients based on historical irradiance distributions specific to Europe or California. These coefficients often fail to reflect local conditions in regions such as Brazil, where solar deployment is expanding rapidly.
The new Brazilian metric was derived from ten years of five-minute irradiance data collected from 137 cities across the country. Statistical analysis showed minimal variation between state, regional, and national weighting coefficients, supporting the use of a single representative equation for practical evaluations nationwide. Eight commercial PV inverters were tested under standardised laboratory conditions, confirming the robustness of the approach.
Comparison with EURO and CEC metrics showed small discrepancies, with median differences of 0.16 percentage points for BR minus EURO and −0.04 percentage points for BR minus CEC. Both confidence intervals included zero, indicating no systematic bias relative to existing international standards. Researchers also proposed a reduced-load testing protocol that cuts laboratory testing time by around 50% while maintaining a maximum deviation of just 0.09 percentage points, offering a more efficient method for benchmarking and routine verification.
The study highlights the potential to optimise testing procedures for single-phase grid-connected PV inverters up to 10 kW. Future work will explore whether the methodology can be extended to higher-power inverters, wider operating voltages, and different grid conditions to support broader standardisation efforts and efficiency improvements across Brazil’s rapidly growing solar market.
Author: Bryan Groenendaal
