I have version 0.2 in my London apartment - the bottom element of the water heater is connected to a different electric supply, with a separate meter, with energy that's almost 3 times cheaper than the rest of the wiring energy. The catch? The circuit is powered only when the power company feels like it (i.e. They need to dump excessive power somewhere), but they guarantee 2h power on by day and 6h by night.

Since this is the bottom element, and the top element is controlled by a thermostat (guaranteeing hot water on demand), this is a great setup for both the consumer and the power company!