When the grid is available, power produced by your solar system is used by the home and excess energy is sent into the utility grid. In the event of a power outage the backup inverter will automatically turn on to power critical appliances such as the fridge/freezer, lights, well pump, computer, phone and more. The combination of solar energy and battery storage works seamlessly to provide power to essential appliances during an outage, working similar to an off-grid system.
An off-grid or standalone photovoltaic system is when your solar photovoltaic system is not connected to the utility grid and you are producing your own electricity via solar, wind, microhydro, generator, etc. These systems will generally have a battery bank in order to store the electricity for use when needed.