Powerline communications strategy enabling fully decentralized control of AC-stacked PV inverters

Cascaded or distributed module-level inverters are becoming increasingly desirable for photovoltaic applications. The authors have demonstrated an AC-stacked topology that allows each inverter to operate completely autonomously from all the others. The only required communications is a low-bandwidth synchronization signal communicated from the point-of-grid-connection. This paper describes the communications strategy that needed to be developed to ensure robust field operation of the entire PV string. The approach has been used to allow an 8-module, 120V RMS string to operate in the field for over six months without any synchronization or controls-related failures.