I buy 750 watt APC UPC on ebay for $35 and I put alligaor clips on them and hook them up to Group 36 deep cycle ( if I remember 100 amp hour battery). I use several of them, one runs my DSL, cameras in that location, and electric fence. The one in my office which runs at full 750 watt runs for about 3.5 hours during power outage. It would be nice to modify a on-demand generator with a start switch hooked up to an arduino to turn it on when the power level goes down. That might be a project one day. Also a propane conversion for the generator and a large tank. I also have 1000w in solar panels to install, to be part of the same system.