Characterization of small photovoltaic inverters for harmonic modeling

Some commercially available photovoltaic (PV) inverters with rated current below 16 A are systematically characterized in terms of harmonic emission by laboratory measurements. The test stand allows the analysis of a large number of test states by using an fully automated test procedure. It is shown that the current emission of inverters can be strongly dependent on the existing voltage harmonics. In order to quantify this influence a sensitivity index is introduced. The paper shows furthermore that the network impedance at the connection point can also impact the harmonic emission. The results of the study give a first more detailed overview of the harmonic characteristics of small PV inverters and form the basis for the development of accurate and reliable models.