# Common-Ground Photovoltaic Inverters for Leakage Current Mitigation: Comparative Review
## 3 General Discussion
This inverter can offer only three voltage levels; thus, compared to other inverters with more voltage levels, a larger filter size is needed;
* The boost CG inverter is presented in [58; 59] and shown in Figure 5e. This inverter can offer continuous input current along with high boosting gain. In addition, it does not need a high capacitance value for power decoupling; only one capacitor with 47 uF has been adopted for the 440 W prototype. This inverter needs five switches and does not use any diodes. The reported efficiency is about 95.5% for the 440 W prototype. This inverter can offer only three voltage levels. DC current component can be generated due to using an inequal number of switches during positive and negative half-cycles;
* The current-source CG inverter is presented in [36; 37] and shown in Figure 3a. This inverter needs only four switches while it can offer continuous input current along \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Converter** & **Features** & \multicolumn{2}{c}{**Limitations**} \\ \hline  & & & \(\bullet\) & The input current is discontinuous. \\  & & & \(\bullet\) & Large number of switches is needed. Thus, more complexity and low reliability are expected. \\  & & & \(\bullet\) & High capacitances are required for boost operation \\ Refs. [76; 77; 78] & \(\bullet\) & No magnetic components are needed. & \(\bullet\) & The switches should be over-rated to withstand the capacitors currents during connection and disconnection \\  & & & \(\bullet\) & The boosting gain is low. \\ \hline  & & & \(\bullet\) & Discontinuous input current \\  & & & \(\bullet\) & 3 capacitors with large capacitances are needed. \\  & & & \(\bullet\) & High number of components increases the cost and size. \\ Ref. [79] & \(\bullet\) & It offers 5 level operation. & \(\bullet\) & The switches should be over-rated to withstand the capacitors currents during connection and disconnection \\  & & & \(\bullet\) & The boosting gain is low. \\ \hline  & & & \(\bullet\) & Two capacitors with high capacitance values are needed \\ Ref. [80] & \(\bullet\) & It can offer 5 voltage levels. Thus, a small filter size is needed. & \(\bullet\) & High magnetic inductance is required \\  & \(\bullet\) & The input current is continuous. & \(\bullet\) & Its boosting gain is relatively low. \\ \hline  & & & \(\bullet\) & It cannot offer a zero-voltage state; thus, a larger filter size is required compared to five level topologies \\ Ref. [81] & \(\bullet\) & It can offer 4 voltage levels. & \(\bullet\) & It needs a high number of capacitors, and the high capacitance value is expected to balance the capacitors voltages \\  & & & \(\bullet\) & Its boosting gain is low. \\ \hline  & & \(\bullet\) & The input current is continuous. & \\ Ref. [82] & \(\bullet\) & Low number of switches. & \(\bullet\) & Large inductance value is needed. \\ \hline  & & & \(\bullet\) & It needs a high number of semiconductors. \\ Ref. [83] & \(\bullet\) & The input current is continuous. & \(\bullet\) & High input capacitance is needed. \\ \hline \hline \end{tabular}
\end{table} 
Table 7: _Cont._with high boosting gain. This inverter does not use any diodes. The reported efficiency is about 95.7% for the 300 W prototype. However, it needs a high capacitance value for power decoupling; one capacitor with 2.2 mF has been used for the 300 W prototype. In addition, it needs two inductors (0.25 and 0.5 mH); this can increase the size and cost;
* The boost CG inverter is presented in [54] and shown in Figure 5a. This inverter can offer high boosting gain along with continuous input current. In addition, low capacitance and inductance values are needed. However, this inverter needs seven switches and three diodes; this increases its cost and decreases efficiency. This inverter can offer only three voltage levels. The reported efficiency is about 94.4% for the 300 W prototype;
* The boost CG inverter is presented in [63] and shown in Figure 5i. This inverter can offer five voltage levels, high boosting gain, and continuous input current.