It's an optional opt-in and the rewards are pretty good. Some places don't even allow you to install solar because planning a national grid power demand is not easy and solar generation needs to be taken into account and it depends on a lot of factors, it's a solvable problem for sure but these companies aren't known for their technological innovations..

You also don't want your power provider to build expensive peaker plants for the occasional peak demands. Programs like these and other DER programs help flatten out the curve and lower yours and everyone else's bill.