I managed to go a week off the grid a couple years ago after a cyclone on a 27k~ AUD system that includes a septic system, home servers, starlink and the rest.

The servers obviously had to come down a few nights, but never had to bring down the fridge or anything critical. Didn't even have proper 4/5g service for a few days.

Main issue was the hot water tank which could have in theory been hooked up to my gas via an instant hot water heater for such occasions.