# Common-Ground Photovoltaic Inverters for Leakage Current Mitigation: Comparative Review
## 1 Introduction
#### 3.1.1 Generation mechanism of leakage current
This is achieved through inserting extra switches into the full-bridge inverter either on the dc or ac side [9, 23, 24, 25]. However, this will need extra switches, which increases the cost. In addition, perfect disconnection cannot be realized because of the switch parasitic capacitance [26]. - Bypassing the parasitic capacitance of PV through using common-ground converters. This represents the most effective solution as it offers complete mitigation of the leakage current by providing a solid connection between the negative terminal photovoltaic modules and the neutral of the grid side. In addition, the grounding of a PV system can minimize the effects of lighting and other surges [27]. - Table 2 summarizes the above-mentioned solutions to mitigate the leakage current. -There are some survey articles that have been presented about leakage current mitigation methods in PV systems, e.g., the work of [1; 3; 8; 10; 28; 29; 30]. In this literature, a common-ground configuration has been presented as an effective solution for the leakage current problem; a few examples of common-ground inverters have been discussed in these papers. However, a large number of common-ground converters have already been presented in the literature. Up to our best knowledge, there is no reported work exploring the common-ground inverters and showing their advantages and disadvantages in terms of the other features required in PV systems; these features can include size, cost, boosting capability, possibility of block DC currents, and their capability to offer multilevel shaping of output voltage. Accordingly, this paper introduces comprehensive review and classification for various common-ground PV inverters. Thus, a clear picture of the advantages and disadvantages of these inverters is clarified. This provides a useful indication for a trade-off between gaining some advantages and losing others in PV systems. In addition, the poten  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Mitigation Method** & & **Advantages** & **Disadvantages** \\ \hline \multirow{8}{*}{Using transformer-based converters} & \(\bullet\) & Almost complete mitigation of the leakage current. & \multirow{8}{*}{Transformers degrade of the power density, increase the cost, and decrease the efficiency of PV systems} \\  & \(\bullet\) & It can eliminate the injection of DC current into the grid. & \multirow{8}{*}{\(\bullet\)} \\  & \(\bullet\) & Transformers can offer high boosting gain & & \\ \hline \multirow{8}{*}{Using common-mode (CM) chokes} & \(\bullet\) & Compared to high-frequency transformers, it offers significant reduction in weight and size. Further reduction can be acquired using magnetic integration design. & \multirow{8}{*}{\(\bullet\)} \\  & \(\bullet\) & Compared to high-frequency transformers, it offers significant reduction in weight and size. tails for optimization based on different performance indicators are identified. According to this study, some recommendations for future research topics are presented. Following this introduction, the common-ground converters are classified into current-source and voltage-source converters; the last category is further classified into bucking, boosting, and buck-boost converters. Then, a number of characteristics are identified. In terms of these characteristics, a detailed discussion for the different common-ground converters is introduced, and the advantages and disadvantages of the different common-ground converters are determined. Accordingly, general discussion is introduced to identify the best candidate converters for the cost-effective and efficient operation of PV systems. Finally, some research topics are suggested for future work, and a conclusion for the overall results is introduced.