It sure used to be, but I think battery backups that cover a whole house for 24h is cheaper than a diesel generator that can do the same now. Depending on your situation you can make it back in savings even without solar panels. (Charge when electricity is cheap, use when expensive).
Piped gas generators is a thing I had no idea existed until now! Edit: Curious to learn if they are a common thing?
25 kWh covers maybe 1-2 hours in a worst-case scenario, and that’s with only a peak eleven-kilowatt output. You’d need ~24 kilowatts peak to cover a full 100-amp old-style mains feed for a house. This is just basic math — 100 amps times 240VAC == 24 kilowatts.
Most houses here in Texas are now built with 200-amp mains feeds. So, you’d need ~50 kilowatts peak. And if you really can get two hours of runtime for 25 kWh, then you would need 300 kWh to get 24 hours of runtime.
Check the prices for batteries and inverters. 50 kilowatts peak and 300 kWh runtime is a lot more expensive than you realize.
Maybe one day, when batteries get much, much, much cheaper than they are today, you will be able to afford that kind of system. But today, a 24 kilowatt natural gas generator is a lot cheaper.