Abstract: An electricity storage system includes a main body and a portable unit. The main body includes a casing, a first storage battery module that stores power, and a first terminal unit to supply the power. The portable unit includes a second terminal unit and a second storage battery module, and is attachable to and detachable from the first terminal unit. The second terminal unit is electrically connectable to the first terminal unit and receives the power supplied from the main body. The second storage battery module has a storage capacity less than the first storage battery module. The portable unit further includes a charging controller, upon determination of power supply from the system power supply has been stopped, the charging controller controls a charging rate for the second storage battery module to be charged at least one of a normal mode and a high-speed mode.

Abstract: An electricity storage system is connected to a power conditioner (PCS) connected to a system power supply and includes: a main body which includes a first storage battery module that stores power supplied from the PCS, a casing that encloses the first storage battery module, and a first terminal unit that is used to supply the power; and a portable unit which is attachable to and detachable from the first terminal unit and includes a second terminal unit that is electrically connectable to the first terminal unit and receives the power supplied from the main body, and a second storage battery module that has a storage capacity less than the first storage battery module and is charged with the power supplied from the main body via the second terminal unit, and the first terminal unit is located on the side of a side surface of the casing.