The pricing should definitely have limits. I could see the rates being something like $0.05 at the lowest and and $0.50 at the highest. It would still be worth it to min/max your electricity bill but if you absolutely needed to use something at peak, you're not going to go broke over it.

I think a better solution is to add this as an option for the power providers we have now. Allow those who want to min/max their energy bills (and have the equipment for it) do so as an opt-in. Poor people who cannot afford the new equipment can still opt-in and only use electricity for times when it is cheap. People who don't care and don't have automation doing the work for them can live life just like they would have, with set rates for their electricity.