FSEC has partnered with Sandia National Laboratories (SNL), the Southwest Technical Development Institute (SWTDI), and the California Energy Commissions Public Interest Energy Research (CEC PIER) to characterize the performance of PV inverters operating over extended periods of time. As part of this characterization, SNL executed an initial performance characterization in the laboratory to be repeated at one or two year intervals. These inverters were then sent to the above test facilities for installation and long-term testing.
To perform this long- term testing, FSEC built an inverter test facility made up of a configurable 10.1 kW PV array and four test beds. Each test bed was set up to monitor the following parameters: DC voltage, DC current, AC Voltage, AC Power and inverter temperature. Solar irradiance, ambient temperature, and several PV array temperatures were recorded by a separate, synchronized data logger. Four inverters were selected for testing: the Fronius IG 3000, the Xantrex GT 3.0, the Sunny Boy 2500, and the PV Powered 2800.
The three inverters were loaded with a PV array close to the maximum power limit allowed by the inverter and were within 100 W of one another. Since the PV array for each inverter used identical PV modules mounted in the same orientation, it is easier to compare the performance of the three inverters based on energy output.