Yes, in my house that is implemented as a ripple control "receiver", which switches on a circuit that has its own meter. The receiver is a rather simple thing

Yes, in my house that is implemented as a ripple control "receiver", which switches on a circuit that has its own meter. The receiver is a rather simple thing I think; basically a high pass filter connected to the mains, with the filter output driving the coil in a relay. It audibly hums when ripple is on. Every couple months, the meter reader comes by and records the total amp*hours consumed at "night rate" and "normal rate". So, it's important to note that the old system doesn't allow one to run the heat pump both whenever it's wanted, and also on the lower price ripple-controlled power. Similarly in the other direction, it doesn't make sense to use ripple control to decide when to feed back in to the grid if you have generating capacity from PV or whatever.