Grid-tied systems with battery backup are the most flexible solar electrical systems. They work essentially the same way regular grid-tied systems work except they allow you to store some of the power you make.
You can choose to run your home or business entirely off your solar panels and batteries, drawing from the grid only as a last resort. You can also do the reverse and use your batteries only if the utility grid goes down so that you can maintain full power operation. Another option is you can use the utility grid to charge batteries when there is no sun for days.
These pole mounted arrays are part of a grid tied with battery backup system. Each array consists of nine Sharp 224 watt panels. The system is capable of producing up to 4000 watts of DC power per hour.
This photo demonstrates a typical equipment space for an inverter, a control panel, two charge controllers and a battery box.
This system consists of a Xantrex XW4548 inverter which is located behind the door on the left.
The XW4548 will detect when the grid power goes down and will automatically switch over to the battery backup system.