Overview of micro-inverters as a challenging technology in photovoltaic applications

One of the key components of the photovoltaic (PV) system is inverters due to their function as being an operative interface between PV and the utility grid or residential application. In addition, they can be employed as power quality conditioners at the point of common coupling (PCC). It should be noted that in inverter technologies, there has been an increasing interest to achieve robust output power injection capabilities with lesser design complexity in terms of controller part and power circuit topology. Micro-inverters (MIs) are module based type of inverters that have aroused much interest in recent years. Owing to their distributed architecture mounted with individual PV modules, system reliability can be improved remarkably by using MIs. Furthermore, a module based nature of the MI architecture provides a number of advantages, such as low converter power rating, low power losses, accurate maximum power point tracking (MPPT) ability against partially shading conditions and elimination of PV panel mismatches. However, there is still known weighted conversion efficiency of MIs ranges between 90% and 95%. Therefore, novel designs focus on the known weak aspects of traditional MIs and their failure mechanisms. In this paper, state-of-the-art technologies for MIs with a detailed survey on the technical features consisting of power circuit configuration, control structures, grid compatibility abilities, decoupling capacitor placement, energy harvesting capabilities, and safety mechanisms are presented. Additionally, elaborated comparison on MIs topologies is realized and some future research fields on MIs are summarized.