Energy coupling method and system for household energy storage

An energy coupling method for household energy storage is performed by an energy management system (EMS). The method includes: monitoring an electricity grid supplying power to a household electricity grid that is managed by the EMS; and in response to an outage of the electricity grid, disconnecting the household electricity grid from the electricity grid, and turning on a portable generator that is connected to the household electricity grid through an AC-to-AC converter, the AC-to-AC converter being capable of outputting a generated AC power that is synchronized to the household electricity grid.