NYSEG charges significantly more/less for electrical power at Thunder Ridge depending on the time of day... and we're smack in the middle of suburban NY. So it's definitely not a rural/MRV thing. It's more expensive in the day and at night it's a lot cheaper as demand drops off. This is at least my understanding of it.
That's still a little different than a power company outright saying "stop using power during these specific hours on this particular day since we anticipate unusually high demand" though.