As shown in diagram above, On Grid system will generate power from Solar Panels and feed the load. It is also connected to utility grid. In case the load is less than the generation, the unit starts feeding the power back to utility which is metered separately so that the same power can be drawn free / at concessional rates. In most of states in India do not allow to back freed the grid for safety reasons. Pl. check the provisions in your state before planning.

As shown in diagram above, Off Grid system will generate power from Solar Panels and feed the load. It is also connected to utility grid. In case the load is less than the generation, the power is stored in battery or the power goes waste if the batteries are fully charged. The load works in isolation with grid. These type of systems generally are like conventional inverter circuit where selected load is put on the system and it draws power from the grid only when the solar voltage drops or to charge the batteries .