These spot price contracts for end users do exist in many places (don't know about SA specifically). They haven't been particularly popular; I guess most people are scared about the other side of the coin, will I accidentally drain my bank account if I do my laundry when prices are at the roof limit?

It probably works best when you only have some sockets in a home that are on spot price contracts. And on those sockets, you have plugged in a washer/freezer/AC that is smart enough to receive spot price information and turn on and off as prices rise or fall. We're not quite there with all the pieces of the puzzle, but it's all technically possible now and likely much cheaper than using batteries to load-shift.