DC current injection into the network from transformerless and LF transformer photovoltaic inverters

The present paper is focused on the study of the DC current injection in the case of photovoltaic (PV) inverters. The source of the leakage current of the transformerless PV inverters is deeply studied among the three most relevant groups that coexist in the market. This study includes measurements of two types of inverters (transformerless and transformer PV inverters) in order to evaluate and compare the behaviour of the injection of the DC current into the grid. According to the assessment of the measurements, the results show that in both cases there is evidence of DC current in the AC grid side, overcoming the limit applied on most of the standards.