When the grid is running properly, the home or business will use power generated from the solar panels or pull electricity from the grid.
Any excess power generated over and above the requirements go back to the utility company for credits on the power bill in areas where net-metering is available.
In the event of grid blackouts, these systems will switch to “off-grid mode” drawing power stored in the battery bank to power the home AND using the solar panels to recharge your battery bank.