Grid-tied systems are connected to utility power. Instead of storing excess power in batteries, a grid-tied system sells it back to the utility. These battery-free systems are lower maintenance and lower cost than an off-grid or multimode system. Grid-tied systems need not provide all of the electrical needs of the building as the utility is always connected.
A multi-mode system combines a grid-tied system with the ability to store energy in a battery bank for use during a power outage or anytime you wish to disconnect from the utility grid. In addition, you are also able to export excess power back to the electric utility.
Off-grid systems are not connected to any utility power. They store power in batteries to be used whenever the sun is not present. Off-grid systems require daily monitoring of your electrical usage. They provide energy independence and are most cost-effective for remote locations with no existing utility service.
