her criteria is to be able to run everything in the house if the power goes out.
???
Good Luck. Unless you are billionaire, that is a pretty steep order.
Very expensive requirement.
Better strategy is to assume there will loss of food stuffs in the fridge and plan on using them before they go bad on you.
It costs about $15k or so to get the whole system together. It hardly requires being a billionaire. IMHO, it’s a worthwhile investment.