Energies 2023, 16, 269. https://doi.org/10.3390/en16010269 www.mdpi.com/journal/energies Review A Comprehensive Review on Common-Mode Voltage of Three-Phase Quasi-Z Source Inverters for Photovoltaic Applications Sherif M. Dabour 1,2, *, Noha El-hendawy 1 , Ahmed A. Aboushady 2 , Mohamed Emad Farrag 2 and Essam M. Rashad 1 1 Department of Electrical Power and Machines Engineering, Tanta University, Tanta 31733, Egypt 2 SMART Technology Centre, School of Computing, Engineering, and Built Environment, Glasgow Caledonian University, Glasgow G4 0BA, UK * Correspondence: sherif.dabour@ieee.org or sherif.dabour@gcu.ac.uk Abstract: Inverters with Quasi-Z-Source Networks (QZSN) provide DC-DC boosting and DC-AC conversion in a single stage. It offers reduced cost, complexity, and volume compared with the clas- sical two-stage conversion system, which is composed of a boost converter followed by a Voltage- Source-Inverter (VSI). Further, QZSI provides superior conversion characteristics for single-stage grid-connected photovoltaic transformerless systems. However, the absence of galvanic isolation in these systems makes it possible to allow leakage current through these systems’ parasitic capaci- tances due to the high-frequency Common-Mode Voltage (CMV) generated by the Pulse Width Modulation (PWM) nature of the inverter output voltages. As a result of this current, critical safety issues may arise with PV systems. Many PWM techniques have been presented in recent years for QZSIs. This paper is intended to provide a comprehensive analysis and review study of the charac- teristics of most of these PWM techniques in terms of CMV and leakage currents. In this study, closed-form equations have been derived to determine the effective CMV and leakage current anal- yses for all modulation techniques. Analytical and simulation approaches are used to identify schemes with the lowest CMV and current leakage effects. Moreover, the experimental setup is pre- sented by applying the Simple-Boost Modified Space Vector Modulation (SB-MSVM) technique. Keywords: Quasi-Z-source network; PV inverters; common-mode voltage; leakage current analysis 1. Introduction In recent years, advances in power electronics converters topologies and modulations have paved the way for developing high-performance Renewable Energy Systems (RES). Among the various RES currently emerging in the world, the Photovoltaic (PV) system stands out, which is a highly reliable, clean and noiseless method of producing electricity [1,2]. PV technology has grown to solve problems related to conventional power plants. Based on the snapshot of the PV technology report in February 2022 [3], a graph showing the evolution of solar PV capacity worldwide in the last 11 years is depicted in Figure 1. It shows how solar PV power systems are expected to provide more energy worldwide. From 2010 to 2021, annual global PV capacity additions grew from 17 GWdc to about 180 GWdc, and the total cumulative installed capacity for PV at the end of 2021 reached at least 939 GWdc. In Africa, for example, solar annual PV capacity increased from 1.5 GW in 2014 to more than 8 GW in 2019 [4]. This growth is attributed to different countries in Africa. For example, the Benban complex in Upper Egypt today is the largest solar project in Africa and one of the largest solar installations in the world, with around 2 GW of AC power [5]. The Benban project comprises 41 individual plants consisting of 7.2 million PV panels. Thirty-one plants each Citation: Dabour, S.M.; El-hendawy, N.; Aboushady, Ahmed A; Farrag, M.E.; Rashad, E.M. A Comprehensive Review on Common-Mode Voltage of Three- Phase Quasi-Z Source Inverters for Photovoltaic Applications. Energies 2023, 16, 269. https://doi.org/ 10.3390/en16010269 Academic Editor: Frede Blaabjerg Received: 1 December 2022 Revised: 20 December 2022 Accepted: 22 December 2022 Published: 26 December 2022 Copyright: © 2022 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https://cre- ativecommons.org/licenses/by/4.0/).