My Eddi is finally setup.
What on earth is an Eddi?
Good question – it is a solar diverter and to be fair, it was setup’ish, it’s just now talking to the internet.
Why, oh why…
Hey, this is my thing. Everyone needs a hobby!
A solar diverter is something we have had since we first got our solar panels and our old one, a Solar iBoost, was exceptionally handy when our boiler stopped working or during the summer, when any spare power we had generated would heat our hot water rather than just go back onto the grid.
A simple monitor reads what is coming off the roof and what is being used. If more is being generated than used, the immersion heater is used as a solar dump.
Our Solar iBoost was simple but did a great job. The Eddi2 is a little more complicated but allows us to set everything up on an app and track how much we are diverting too.
This functionality is very useful if you have an air sourced heat pump during the winter. Setting a schedule allows the hot water tank to heat up to 60°C or so using the immersion heater, but powered from the solar cells.
But, unless the temperature gets to sub 4°C, the air sourced heat pump is going to be more efficient – yes, it goes down to getting 3.4kWh of heat out of 1kWh of input energy, but that is way better than the 1kWh to 1kWh of input output we get from the Eddi.
That doesn’t make the Eddi only useful while it’s cold, our recent travels made the Eddi invaluable not least in keeping the battery 100% full while reducing our overall usage.
Of course, during a heat wave, this is not as efficient as using the air sourced heat pump, though any spare would be used for that (were the hot water cool enough). In fact, because solar cells do not perform as well when it is hot, it may be much more expensive to use the solar divert function in place of the heat pump’s hygiene programme.
Hygiene programme?
Heat pumps typically heat “hot” water to between 40°C and 50°C, which is plenty for a lovely hot bath or shower, or washing up, or cleaning dishes or clothes..
But it is also a temperature which can allow legionella to thrive. So, at least once a week, aim to have your water taken up to 60°C or 65°C for an hour or so.
We’ve timed ours during the summer to run when the solar divert is unlikely to be kicking in.
Of course, the solar divert is doing this task during the winter months, when the cells are operating at their peak, a couple of times a week.
Saving us a little money but making sure everything is kept in tip top condition from an investation point of view. We’re happy, the legionella is not, as our bills are kept as low as possible.
Are you sure this is worth all this fuss?
Yes. You need to do this kind of thing with a gas boiler, but it requires the same kind of “fuss” or rather conscious decisions being made on what happens: when and where if you are looking to reduce your carbon footprint and be a responsible user.
We’re just doing the same with our electric powered heating, which measn the decisions are a bit more tangible when it comes to tracking usage.
Speaking of which, I’m off to jump in the bath before the hygiene programme starts.
Posted: August 2nd, 2025 under Driving off the grid.