I live in the country and use propane heat. When I looked at the backup generator, I discovered that it would use about 400 gallons of propane in a week...if my calculations were right.
I heat with 800 or so gallons for an entire winter. This year was so mild I got by with just one.
IOW, it will cost you with today’s low prices for propane about 500 bucks to generate a week’s worth of electricity. I’m assuming you’re on natural gas, but the prices are about the same.
My calculations could have been off, but I used their literature.
It’s cheaper to get an external 5 kw generator and use gasoline for me, and just be selective which appliances I’m using at any given time.
I don’t have natural gas available where I live, so I have to look at propane with a tank. The cost of operating it isn’t a huge concern, since this is really just for emergency situations. If we get a direct hit with a hurricane we’re told to expect a 3 week outage... which in the summer in south Florida would be miserable, and damaging to a lot of delicate artwork we have in the house (high humidity... works on paper).
That's what I've done. I have a 70 gallon supply of gasoline stabilized with Pri-G in 5 gal. containers that gets rotated on a regular basis.
With some heavy duty cabling to get to the fridge and freezer...and some low voltage lighting and the thermostat for the gas heat, I think I'm all set. Not a replacement for a whole house solution but it will maintain food, heat and light.