Robustness evaluation of transformerless PV inverter topologies

Transformerless PV inverter topologies allow the PV inverter size and weight to be reduced while reaching a higher efficiency. The drawbacks of these topologies are that DC current components at the grid side must be cancelled by means of the employed controller and the number of power devices required to avoid currents through the parasitic capacitor of the PV generator increases. These topologies have been analysed in the literature but physical variations of power devices due to the manufacturing process have not been taken into account. This manuscript analyses the effect of such physical variations on the performance of three commonly employed transformerless topologies: H5, HERIC and Half-Bridge NPC. The impact of the parameter variations is compared regarding the efficiencies at different power levels, the European Efficiency and the DC current components. The results indicate that physical variations lead to different behaviors regarding the robustness of the analysed topologies. By means of statistical analyses these differences are obtained and exposed.