I had a whole home one and I had 400 amp service for the home because I had a large home and lots of electricity being used in it. I had a Generac and transfer switch that could handle the whole load and never had an issue with it. Would do its weekly self test and come on by itself which was comforting to hear. Ran on propane out in the country north and east of Kiowa so I know what you are saying about not wanting to count on the electric always being there.