Evaluation of Low-Voltage Loss under Partial Shading Conditions in Solar Photovoltaic Systems

Partial shading significantly deteriorates the performance of a string inverter based grid-tied photovoltaic (PV) systems. Typically, partial shading losses are quantified under mismatch losses. In this work, we identify another related loss which is likely to occur under partial shading conditions due to sub-optimal voltage operation in a typical string inverter. These losses occur due to operational voltage range limitations in an inverter where a large number of series modules are bypassed in high shading scenario. We quantify this loss for a typical roof-top solar PV implementation and results show losses up to 5% in some cases. The evaluations performed in this work gives insights into the performance of these systems under high shade scenarios. While a range of inverters and modules with different parameters and ratings are available in the market, the performance of a PV system can be improved by proper selection of components in deployments where high shade is anticipated.