in 2007 when CFE wasn't as reliable as it is now, I bought a battery backup system that worked when CFE was down. I still have that system and I guess by doubling or tripling the number of batteries I have I might have enough batteries to work everything when the power is out, but I sure wouldn't want to be forced to do this. It would be frightenly expensive. And because of heavy battery usage, I would need to replace my expensive deep cell Trojan golf cart 6 volt batteries much more often.
Today I have enough batteries for one refrig, one or two lights in each room, one TV and my laptop.
Think about all those extra high power demand items like a swimming pool pump, an irrigation pump, garage door openers etc, And you get the idea. It just doesn't make sense in most cases.