750kg (500 gal) is the smallest you can get around here.

A house backup generator uses something like 3kg of propane per hour idle, so that tank will keep your fridge on for ~ 10 days. Our area (outskirts of Silicon Valley) saw 20-30 day power outages with essentially no sun that year. The weather is rapidly worsening due to climate change, but they are also hardening the infrastructure.

Now, with a battery + backup generator + wood stove, you only need to run the generator to charge the house batteries. Assume a duty cycle of a few hours of optimal efficiency generator per day, wood heating, and you can easily exceed the 30 day target. At that point the sun should be out, at least here in California, or at least the roads will be open enough to let the propane supply chain adapt to the demand.

For the EV route, buy a truck or SUV with vehicle to home support, and a house battery that can charge off the vehicle. The truck has 2-4x a house battery in it. This plan assumes there’s a fast charger in town (ideally near the grocery store), and it’s under ~ 100 miles round trip.

Edit: I’ll add local pricing: A used >= 100 kwh ev is about $30K. The generator + permits + tank is > $20k.

With the ev route, you also get a nice car.

I didn’t price out generator + 2000 gallons of propane storage. It’d guess it’s about $30k.

Maybe you don't need such a huge generator. Run your fridge and a small heater, and only heat a small section of your house. Were talking about emergencies here, not keeping your hot tub running. I can heat a bedroom easily with a 1500 watt space heater. And my fridge pulls an average of about 150 watts. Quite honestly, a whole house generator is for convenience when there's a tree that falls on a power line. It sounds like a real waste for an actual emergency.