Off grid inverters are designed to operate as a standalone unit and cannot provide power to feed back into the grid (they cannot synchronise with the grid). These inverters are powered by mains power, solar panels and a battery bank. The inverter can be programmed to prioritise power from the mains supply, solar panels or battery bank. Note, there are many inverters that are marketed as hybrid inverters however they are actually off grid inverters (they cannot synchronise with the grid).