S
silverpete
I know that this is an old thread, but I was looking for this sort of info 2 months ago, and I hope my experience will be helpful to other forum readers.
I'm not qualified to say which is the best in the market, but I have recently installed the ImmerSUN T1060 diverter and I'm very impressed. It seems well built, and unlike so many electrical fittings, it feels like it's been designed with one eye on the installer - eg adequate space for the incoming cables, options to come in from different angles, etc.
The display is more helpful than I had expected. It shows me how much power is being imported from the grid, or exported to the grid. Easy graphics (smiley face or grim face!) make it instantly obvious whether I'm in deficit or not, and how much power is being diverted to my immersion heater.
Since installation in late June 2017, I haven't had to use the gas boiler at all. Nil. Zero gas. Obviously, this is the period of highest solar gain and won't last all year.
My first full month used ÂŁ11 worth of electricity (at grid pricing) to drive my immersion heater. On the one hand, that overstates the saving, as I wouldn't normally use an electric immersion heater. On the other hand, I'm a light user (single bloke, who splits living time between here and g/f's place) so a heavier user of hot water would have made greater use of surplus power. On a bright day, my immersion is always "sated" by midday.
I've turned the immersion thermostat up (almost) to the highest setting, so my hot water is REALLY hot. This means it easily lasts until the next morning for plenty of hot shower water. On the other hand, the thermostat setting for the boiler (on the Megaflow) is turned down quite low so that the boiler would clearly be the secondary source.
Other benefits: the digital display has been helpful in showing me when peak pv generation occurs. Surprised to see the dramatic difference between a very bright summer day with some cloud cover (maybe 1kw surplus) and when the cloud parts, that surplus immediately jumps to 3kw. It's also shown me that my microwave is less efficient than I had imagined, as I can see an instant drain of 1.5kw when it's switched on! This intangible benefit - of understanding how your solar panel generation is behaving throughout the day, and therefore when to use eg the washing machine - this benefit is much underrated. Incidentally, I've now plumbed my washing machine into the hot - making sure to use it when the water isn't scalding - so I'm now saving on that hot water heating bill too.
The unit is sufficiently versatile to allow another circuit to be powered once the primary (ie immersion heater) circuit has been satisfied. So if I want to install e.g. a storage battery, it would be possible.
The most difficult part of the installation was the simple but practical point of finding enough space within the consumer unit to fit the sensor clip around the inbound main "live" meter tail. (There is apparently a wireless sensor available if it has to be positioned in e.g. an outdoor meter cupboard.) Obviously, you need a dedicated circuit to the immersion heater.
I found a refurbed item on Ebay, and paid less than ÂŁ200, so I'm well pleased.
