Here in California, peak AC demand is late afternoon. Environmental thermal mass means peak outdoor temperature happens a fair bit after peak insolation. Structures take even more time to heat up and add additional delay. Finally, people arriving home from work means increased AC use, too.
Demand stays fairly high after it gets dark.
(And it's my understanding most other places keep daytime heat later than here).
This particular one is only mildly effective; precooling can lower later demand somewhat.
My house is very well insulated, but I still cannot coast from 5:30pm to 9:30pm (when windows are sufficient for comfort and demand really starts to slope off) without an excessive amount of prechilling. My structure, insulation, and attic are all preheated by the day's heat and so there is a big warm thermal mass next to my living space.
Also, opening windows overnight increases indoor humidity, which in turn requires more air conditioning the next day.
If it'll save you 10% on your electric bill, would you do it? I would. And reducing peak demand by 10% can really reduce the cost and need for grid battery storage.
Best of all, doing this sort of management of your HVAC system costs you essentially nothing. It's picking money off the ground.
It is not useless but it does have its price in terms of complexity and usability. With off peak at night you tend to run out of hot water during the day at times e.g. if you have visitors.
It is not a new idea and it is no panacea.
I've never seen it mentioned in any articles about baseline and peak power needs, and all that talk about grid batteries.
> and it is no panacea.
Nobody said it was. If it would, say, reduce the need for grid batteries by 10%, that would be an enormous savings. All by changing a new thermostat.
I remember in the 70s energy crisis the appearance of programmable thermostats what would automatically lower the temp at night. My proposal just extends that.
Magically when solar production is at it's peak!
There's no evidence of that. The only evidence is that when the price is exactly the same 24/7, no elasticity is observed.
> and would cost an unbelievable amount of money to replace with electric
I've had to replace gas furnaces and gas water heaters now and then. They don't last more than 10 years or so.
BTW, everybody in Arizona has A/C. Amazingly, A/C demand peaks when the sun is high in the sky.
> I do not know anybody with an electric car
You will.