The GoodWe EM series bi-directional energy storage inverter can be used for both on-grid and off-grid PV systems. During the day, the PV array generates electricity that can be directed to the loads, the grid, or to battery charging, depending on the economics and set-up. The electricity stored can then be released when the loads require it during the night. Additionally, the power grid can also charge the storage devices via the inverter.