Forum Home» Green & Ethical MoneySaving

Solar immersion heater (iBoost) - Using Grid Energy

New Post Advanced Search

Solar immersion heater (iBoost) - Using Grid Energy

edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
6 replies 2.2K views
Alan_BrownAlan_Brown Forumite
200 posts
edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
I have recently had a smart meter fitted, which gives me completely accurate electricity usage to an 'in-home display'. I sat this display next to the iBuddy display and was alarmed to see that there was a huge disparity between the two, often up to 600w difference.

What was alarming is that the iBoost was diverting 'solar' power to my hot water tank, while the smartmeter was saying that I was importing energy from the grid. This must have been happening every day, so far from saving me money by heating water with my solar excess, it will have been using expensive grid electricity to heat some of the water.

I expected a slight discrepancy between the two, considering that the smart meter has to be completely accurate by law and the iBoost is connected to the electricity with a clamp that clips over a wire. I didn't expect a few hundred watts though!

Getting a smart meter has certainly paid off, and the iBoost has now been turned off. I guess I'll have to wait for Zigbee HAN IOT devices to be produced that use signals from the smart meter to turn on and off things like the immersion heater when it detects negative import from the grid.


  • Dave_FowlerDave_Fowler Forumite
    581 posts
    Part of the Furniture 500 Posts Name Dropper
    I'm surprised that the Iboost is so inaccurate. I built my diverter circuit way back in the days when we had the old spinning disc meter which used to go backwards when exporting. With the diverter in place the disc stopped almost still - very slowly creeping backwards.

    Now, when the diverter is in operation, the new digital meter 'importing' LED never flashes and the reverse energy light is usually lit - I think I export about 30W. Surely there must be something wrong with the Iboost if it can't accurately detect a 600W import current flow.

    Dave F
    Solar PV System 1: 2.96kWp South+8 degrees. Roof 38 degrees. 'Normal' system
    Solar PV System 2: 3.00kWp South-4 degrees. Roof 28 degrees. SolarEdge system
    EV car
    Lux LXP 3600 ACS + 4 x 2.4kWh Aoboet LFP 2400 battery storage. Installed Feb 2021
    Location: Bedfordshire
  • ajbellajbell Forumite
    1.2K posts
    My Iboost is spot on and agrees with my smart meter however if you don't have the iboost paired correctly it can be inaccurate. Have you paired it?.
    4kWp, South facing, 16 x phono solar panels, Solis inverter, Lincolnshire.
  • ajbell wrote: »
    My Iboost is spot on and agrees with my smart meter however if you don't have the iboost paired correctly it can be inaccurate. Have you paired it?.

    Thanks. I followed your advise and re-paired the iboost, sender unit and buddy. I also moved the clamp around a little and screwed the sender unit to the wooden backplate and generally tidied up the wires. Not much improvement. I changed the batteries and the iBoost buddy is now only 60 or 70 watts away from the smart meter, which is an acceptable tolerance.

    I'm glad to have sorted it out out, but annoyed that the sender unit didn;t give an indication of low batteries. Makes you wonder how many other solar immersion heaters are out there using mains electricity due to low batteries.

    I noticed that the manufacturers of the iBoost do a mains connector fo rthe sender unit. I think I'll get one of these to prevent this happening again.
  • michaelsmichaels Forumite
    25.5K posts
    Part of the Furniture 10,000 Posts Name Dropper
    Thanks, reminds me to change the batteries - I assumed if they were low it would just not divert rather than divert too much. I don't think the sender unit has any sort of battery indicator? Any way to tell when the batteries need replacing?
    I think....
  • pinnkspinnks Forumite
    834 posts
    Sixth Anniversary 500 Posts Photogenic Rampant Recycler
    My immerSUN has a hard-wired sensor, though a wireless mains version became available with the version 2.

    I wonder if the immerSUN is back on the market - monitoring with myimmerSUN is working but websites not being updated - not that I am in the market for a new one but just wondered as they are/were a good product
    Wiltshire - 5.25kWp
    3.5kWp: 14 x Phono Solar 250 Onyx, Sunny Boy 4000TL, WSW 40 degrees, June 2013
    1.75kWp: 7 x Phono Solar 250 Onyx, Sunny Boy 1600TL, SSE 45 degrees, March 2014
    199 posts
    Sixth Anniversary 100 Posts
    Hi Pinks, I have just connected up an Immersun with the wireless mains
    sensor, it's all under "test" conditions at the moment (!!)
    as the wireless sensor is hanging out of the larder, where the clamp is
    fitted around the pigtail of the consumer unit,
    and it "talks" to the Immersun which is across the kitchen, wired into
    a 13A socket where the immersion supply used to be plugged in,
    via a mechanical 24 hr timer...) and it seems to work perfectly;

    The wireless module shows a green led, which flashes orange on
    occasions, generally when I pass between the two modules!
    and the Immersun diverts anything over and above my 250w base
    power usage, fridge & freezer generally,

    But it does like to export 100w back to the grid, when feeding 1Kw+
    to the immersion, despite it being factory set to divert anything over
    50w above base consumption.
    I hasten to add, the wiring is "temporary", and I do notice "warmth"
    on the 13A plug supply to the Immersun on a good sunny day!

    I have the output from Immersun feeding a multiway socket strip,
    that allows me to try other devices like 1 Kw oil radiators, or a 1 Kw
    kettle, etc. when extra pv power is produced....
    It certainly does NOT like driving a motorised 900W ceramic heater!!
    16 x Enhance 250w panels + SolarEdge Inverter + TREES :(
This discussion has been closed.

Quick links

Essential Money | Who & Where are you? | Work & Benefits | Household and travel | Shopping & Freebies | About MSE | The MoneySavers Arms | Covid-19 & Coronavirus Support