Multilevel Inverters for Grid-Connected Photovoltaic Applications: Examining Emerging Trends

As the cost of photovoltaic (PV) modules and inverters continues to decline, PV power generation is gaining more and more share in the electricity market. The market and its customers are demanding higher-performance inverters in terms of efficiency, power density, module-level control, and increasingly higher voltage and power levels. Because of their outstanding performance, multilevel inverters have attracted the attention of researchers and technology developers alike. This article presents commonly used multilevel inverter technologies for grid-connected PV applications, including five-level inverters, single-phase nonisolated inverters, and three-phase, isolated cascaded H-bridge inverters. Detailed discussions are presented, along with characteristics of PV applications.