Depending on your budget and weather or not you own your house a back-up generator is the way to go. I have a 40kw generator (overkill but free from work) that kicks on if power off for more then 7 seconds. Runs off natural gas. 15kw would be okay for average house, installed cost less then $5,000.00 in this area. I am lucky in that I was able to get it all done in trade.
Erik