A Grid-Interactive system can be seen as a combination of an Off-Grid system (with a battery bank) and a Grid-Tied system (uses the grid as backup and/or sell excess energy into the grid i.e. Nett-Metering).
Thus it is a Commercial Grid-Tied system with a battery bank installed to store some energy for later use or for back-up under grid-failure conditions.
The battery bank can typically be smaller than what is required in an off-grid system; sized to drive just the essential load(s) during a power-outage, with the grid as a reliable backup energy source for bad weather days.
Grid-Interactive System in Commercial or Industrial Scale installations would be used to power essential or mission-critical loads (e.g. Computer server rooms, fridges, key-equipment) during grid-falures and/or would be used to reduce peak loads (i.e. Peak-Shaving), thereby reducing the KVA Load component of the electricity bill.
Good for your business, good for your balance sheet and good for the environment.