Stratification heating can be realized by two ELWA units. Usually one of the devices is installed in the lower third and one in the upper third of the tank. Both devices are set to the same desired temperature and communicate with each other via the DC cabling. With the AC ELWA-E, in combination with the my-PV Meter, even up to eleven devices can  be controlled according to priorities. And with Smart-Home control, even more, depending on the type of system.