High-Power Solar Inverter Efficiency Measurements by Calorimetric and Electric Methods

In this paper, the results of a European efficiency measurement for a 250-kW high-efficiency grid-connected solar inverter are presented. The efficiency measurements are performed both by electrical input-output and calorimetric methods. Two measurement series with input voltage levels of 500 and 750 VDC are carried out. An open- and balance-type calorimeter system that can measure power losses up to 30 kW is introduced and verified by resistor tests. The measurement results and their uncertainty are analyzed and discussed.