What happens if you have a local power outage but they have drained your battery down?
I also have it configured to charge to 100% if there are any weather watches or warnings. That overrides the time-of-use configuration.
We do also have a generator that I can hook up if the batteries get too low. We have enough battery to get us through the night, but we don't have enough solar to keep up in an outage during the darker months, or if we want to run the A/C.
If you cannot install residential solar, don't have enough solar, or have to defend against outages lasting for days or weeks, having the infra available to support an exterior fossil generator is certainly something to consider (main load center transfer switch, receptacle on structure exterior for genset supply to the load center or a subpanel of critical loads).
[1] https://www.basepowercompany.com/ (no affiliation, I just like batteries!)
Combine it with rooftop solar to get the equivalent of free fuel for your generator every time the sun shines.
That is the key—having enough battery to cover an extended outage is very expensive.
My generator can run on natural gas, which is piped to our house and only had one outage in the fourteen years we've lived there (when the gas company replaced lines as part of preventative maintenance). So effectively, we have a redundant electricity source coming into the house. If that was also down, I could also run it on propane or gasoline.
That being said, if I had to pick batteries _or_ a generator, I'd prioritize batteries. We have both, and the batteries cover the majority of outages, while also providing other benefits.
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.