GridZero: This mode is intended for systems that have the utility grid as an input and a sizable amount of renewable energy. The loads will remain connected to the utility grid, but will restrict the grid use except when no other power is available. The default power sources are the batteries and renewable energy, which attempt to “zero” the use of the AC source. The batteries are discharged and recharged (from renewable sources) while remaining grid-connected. This mode does not allow the inverter to charge batteries or sell.