There are UPS systems that can run a house.. Think solarpanels with battery backup for homes that are off the grid?? Any solar company could design a battery bank to operate portions of the home when power is not available from the grid. Or you can just get a commercial UPS system. You will need to know how long they want to last and how much power is needed and size accordingly. I would set it up just like a generator and only put the bare essentials on it such as refridgerator, smokes/security a few lights and so on..

[Link: woodhyrst.com]