A commercial 3.6 kVA inverter designed for solar photovoltaic (PV) applications was tested to determine its performance under variable ac system conditions. The results showed that output real power varied as ac system voltage varied. Even though the inverter is capable of supplying reactive power, it always consumed reactive power from the ac system, and local load reactive power was also supplied by the ac system. Using the test results, a power flow model was developed. The model was demonstrated in a distribution power flow analysis of the IEEE 13-bus test feeder.