Not at all. If you use it with a 3kW element you may well import a lot to heat your water. And with a 1kW element there is the added cost of element plus not a lot of actual PV generation transferred to that element. See all the posts on page 51. These switched type systems, particularly ones that do nto actually measure the amount of house export, have an unproven benefit and many of us think they won’t pay back any time soon, if at all. They are just creating an illusion of diverting enough PV to the immersion to be saleable. You need one that tracks export and puts variable power into the immersion.