Energy management system and grid-connected energy storage system including the energy management system

An energy management system comprising: a first interface for connection to a power generation system; a second interface for connection to a storage device; a third interface for connection to a power grid; a fourth interface for connection to a load; and a controller; wherein the controller is adapted to direct power from the power generation system to at least one of the load, the storage device and the power grid; wherein the controller is adapted to direct power from the power grid to at least one of the load and the storage device; and wherein the controller is adapted to direct power from the storage device to at least one of the load and the power grid.