The Apollo TSW inverter UPS system uses utility power, when available, to charge batteries and keep them ready to take over when the utility grid power is interrupted.
When the utility grid comes back, the loads are automatically transferred back to utility grid power and the built-in charger in the Apollo TSW goes back to work re-charging the batteries to prepare the system for the next utility outage.
The systems are both modular and expandable. The system works well with back-up generator input. A larger battery bank or DC power from PV can be added to the system at any time. The entire system can even be monitored for status and performance via the Internet.