I don't think there really is a simple answer to this issue. If all you have to worry about is blackout with no storm issue, and you can afford it, it is best to hook up to a generator to your house [so it would run without having to manually start it]. This means big money.
As far as the UPS goes, I think it would be very short term power supply. To get a longer running system, you are looking at hundreds of dollars.
Right now I am thinking of a deep cell battery configuartion myself. Water, if your you can get some details from your BF on this, I would appreciate it. What does he expect the run time to be with this setup? How is it hooked up?