Iboost cut in level/ margins and generation levels

edited 11 April 2022 at 10:40AM in Green & ethical MoneySaving
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NoobSolarNoobSolar Forumite
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edited 11 April 2022 at 10:40AM in Green & ethical MoneySaving
Hello all. I have noticed that sometimes my mains meter shows short periods of using mains electricity when I am generating plenty of solar. The iboost, I notice, is often trying to be super accurate and make sure the majority of the power goes into the immersion. Now in the past I doubt most of us would have cared much about seeing a brief period of 115 Watts or 35 Watts, especially as it is only present for a brief period as the iboost adjusts its levels. We might indeed simply reflect on how lucky we are that our 1KW camping kettle is drawing most of its 1KW from the sun, and only 85Watts from the mains.

The thing is, this does mount up these days under current extreme price conditions. In the past, we might not have been at all bothered if one KWH of power usage might accrue over a whole day in such intersticial or marginal moments, or indeed as the solar power fluctuates and the inverter tries to even things out. But today, 1KWH is 30 pence! And I am extremely tight!

My question is: would increasing the iboost+'s cut-in level to above 100W help to improve this? And - is this normal?
Is it simply the case that because applicances vary hugely in the power they draw, (e.g. a washing machine churning, heating, spinning, rinsing, etc) the system is always going to have such periods of 'catch up'?

It is a new installation and I am new to all this - was I naive to hope that when generating loads of power, the meter would continually be reading '0'? What I am noticing is these short periods of draw from the mains prior to it all settling down again to 0W.

And a follow-on question. If it is the case that once has to expect such short periods of cut-in-level margin of error, and that cannot be avoided, what happens if I add a battery? Will that lead to a situation where I simply never use the mains at all unless the battery is depleted or charging up?


London. 6.4kwh system, South facing. 16 Hyundai 400kw all black panels w/ optimisers, 6kw Solaredge HD Wave inverter, Solar Iboost with two immersion heaters on one 240l hw tank. Octopus SVT and Outgoing Agile. Ivar 5 Wood Burning Stove. Crap ICE car saving up but hit hard by prices. Two chickens: 1 Light Sussex, 1 Speckled Rock. Omlet walk-in run. Approx 1.5 eggs per day egg generation rate using Marriage's organic layers pellets.


  • edited 11 April 2022 at 12:46PM
    MeatballsMeatballs Forumite
    538 Posts
    Part of the Furniture 500 Posts Name Dropper Combo Breaker
    edited 11 April 2022 at 12:46PM
    I suspect wireless CT device would be more prone to this as they may have a set delay before they update the main device (maybe they immediately update when a big swing happens?). But hard to tell without access to the designs.

    Noticing similar with my dimplex free e, but I don't have the option to set an export value so it's always aiming for 0.

    Asked on another forum if it was possible to trick the CT to see less export by changing resistor across CT but don't think it would work.

    Was thinking about wiring up the modbus interface on the dimplex reader and then I could tweak the values going into the main unit but first attempt failed. 😭
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