Just looking for general advice around the solar iboost system. I have a 14 panel setup with a 10kw Mira battery set up with the solar iboost (Marlec) system installed (on Octopus although that shouldn't make a difference). I think it seems to be working during the day, diverting energy to the immersion heater, after battery full, but when I boost the hot water say at 9pm, the energy it uses doesn't seem to show on the Fox app (unlike if the kettle was on) and doesn't seem to draw from the energy in the battery. It is working as I can see it on my physical smart meter in the house, but not on the app and battery not draining. Any ideas as I want to use the free / cheap energy from the battery rather than the grid at peak times?
Last edited by tomhawkins83 on Mon Apr 27, 2026 9:46 am, edited 1 time in total.
I am not au fait with this, but it seems like the solar power heads to this, and it is wired up to the mains I presume.
The fact that the Fox system cannot see the energy being used, but your smart meter can, tells me there is likely a split incoming mains, where the power flowing to the booster is not measured by the Fox system.
If you have smart meter billing every 30mins, then you can download your data in a few days from Octopus, and you will probably see it being measured as consumption at 21:00 to 21:29 for example.
The fact that the Fox system cannot see the energy being used, but your smart meter can, tells me there is likely a split incoming mains, where the power flowing to the booster is not measured by the Fox system.
If you have smart meter billing every 30mins, then you can download your data in a few days from Octopus, and you will probably see it being measured as consumption at 21:00 to 21:29 for example.
Thanks - effectively what I'm trying to work out though is "is the immersion using electricity from the battery or the grid?" I want to use the cheap energy, rather than peak prices and it should come from the battery first, but can't tell if it is.
I don't know what your Inverter is, some have 5s refresh times, so you can check almost in realtime the power distribution, otherwise you are stuck with 5m cloud refresh times.
If you have 5s refresh times, can you go and run a boost cycle right now and observe on your phone/tablet the values?
If you have the slower 5m refresh, then you can do the same if you run it for 15mins (checking the meter also for the pulse rate)
If you have 5s refresh times, can you go and run a boost cycle right now and observe on your phone/tablet the values?
If you have the slower 5m refresh, then you can do the same if you run it for 15mins (checking the meter also for the pulse rate)
Fox H1 6kw hybrid invertor. It refreshes every few seconds. Show everything else very clearly - turn on kettle, charge car, washing machine, etc. Doesn't change when immersion goes on and does not show drainage from the battery.
Does your smart meter go nuts when you run a boost, if yes then it must be pulling from the grid and bypassing the Fox kit.tomhawkins83 wrote: ↑Mon Apr 27, 2026 10:08 am Fox H1 6kw hybrid invertor. It refreshes every few seconds. Show everything else very clearly - turn on kettle, charge car, washing machine, etc. Doesn't change when immersion goes on and does not show drainage from the battery.
Yes it does - like when you boil a kettle. Trying to work out why and what I can (if anything) do about it.
When I charge car at 7kwh+ it draws from both the grid and battery as it can't discharge quick enough. I think the immersion element is only 3kw though so not sure why that would be totally from grid and not use battery at all.
When I charge car at 7kwh+ it draws from both the grid and battery as it can't discharge quick enough. I think the immersion element is only 3kw though so not sure why that would be totally from grid and not use battery at all.
You might need to post a picture of your meter cupboard area as a whole overview.
It might be a simple as moving a CT clamp from your Inverter on the correct wire to read you FULL house load, and it would then supply power to the water heater during boost.
It might be a simple as moving a CT clamp from your Inverter on the correct wire to read you FULL house load, and it would then supply power to the water heater during boost.