@tim441 Will do and thanks. So do you have 3 phase into your house? If yes, did you always have it or add it, and if so how much did it cost? My understanding is it is 3 separate feeds and you can jump between them or use all 3 of them at once. I remember reading about then when having the EV charger installed and it said you could only have 6kwh or so unless you have 3 phase, but to be fair, with smart charging, that is more than enough for my MG4, especially as Octopus are bringing in a 6 hour per day cap that can be at any time of the day, to balance the grid.

I've just got to stop looking at the solar app every minute 😉

@fleecy i too have a MG4! 

I only have standard single phase to the house. But as 3 phase is available at the pole the DNO (SSE Networks in my case) was able to switch the phases. The phases will always have some variation between them as the number of houses, demand,  solar supply etc will not be equal.

My switch of phases has probably resulted in a drop of average voltage of up to 2v. Enough to make the difference and take me from regular overvoltage events and inverter tripping to almost none (to date!). Its about a month since the change and includes periods with significant solar prod. So looking good.

@tim441 Fab car. I bought one in 2023 and loved it so much, I bought a 2026 one - lots of lovely new changes and I've just charged it to 100%, with it saying I've 314 miles. It's funny how being a volt head now, those extra 50 miles will make so much difference. I had a year to go on my PCP but the balloon payment was £15k and the car would only be worth £12k, so negative equity. My dealer told me I could have a brand new one with 0% interest and a balloon payment of £10k if I did a voluntary termination. It was a no-brainer.

Re the tripping, I didn't have it yesterday but its a bright one today and supposed to be for the next week (ha) so it will be interesting. Currently shoving 3kw into the grid. Making hay whilst the sun literally shines 😉

@fleecy yes mine is 2023 .. Trophy... via business... 4 year contract.

I will definitely stay EV. But guess I may need to look at BYD for one option. 

Potential V2G, V2H will be part of the thinking but in reality not crucial. I'm sure further down the line it will be standard. But of course likely to require a charger change ...or other changes to wiring etc.

@fleecy - thanks for adding your experiences to this thread.

I clearly need to better explain on the Forum how and why G98-certified inverters are detaching themselves from the grid.

However, these concepts are very difficult to grasp, even if I were to create moving diagrams!

What I've actually been doing is designing & building a set of 3D demonstration models which illustrate the way in which the grid operates. Ie that's the flip-side of the issues which you and Tim are raising here.

That means I'll need to run a 'live' seminar in which attendees can be introduced to those concepts and see how they might apply to the solar panels, EV chargers, heat-pumps and storage batteries which are rapidly being installed in our homes. It needs to be an interactive seminar, rather than a lecture or slide-based presentation.

In short - domestic inverters shouldn't be dropping off the grid due to over/under volts.
Something isn't right if this is happening, but it might be in a neighbour's house rather than yours.

There is a new 'Standard' being implemented by the ENA (Electrical Networks Association) which will lower the domestic 'LV' supplies from the 240v we are used to seeing.

A reduction of 6% is roughly equivalent to allowing households to export up to 6kW per phase, rather than 3.68kW.
But I need to explain this in greater detail because it won't solve the problem of inverters which persist in exporting above the 253v threshold.

Time is short this week. I've just come out of a meeting with NESO, and I'm preparing for a meeting with a senior DNO engineer. This over-volts issue is on the agenda for both meetings.

Please give me more time to think how I can respond to the important problems you're raising...
... without needing to run a national roadshow accompanied by a van-load of demonstration kit.

@transparent Your effort is massively appreciated, not just for those who like the technical side of it but more for the masses who just need it simplified enough to make their own decisions. A modern, dynamic and decentralised grid would be fabulous. A five minute walk and I can look out from the Fylde coast at the forest of windmills offshore. We need to be able to get their output into every home, especially in the winter when solar is way down.

Posted by: @tim441

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Luckily my DNO was helpful & proactive. Switch of phases has very significantly improved the situation. But there is probably still an issue on my local grid at another property that is causing overvoltage. I don't know if the DNO will track it down - or have bigger fish to fry!

Tim - your DNO is back on the case.

I spent 20mins yesterday in conversation with a senior SSE Engineer.

Posted by: @l8again

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A local DNO manager told me that 75% of his time is now spent on resolving under/overvoltage situations.

That shouldn't be happening, of course.

No G98/G99 certified device should be capable of taking the grid above 253v.

In Tim's case there is reasonable evidence that there is an inverter nearby which is doing just that...
... and in a sustained way, which causers other G98 devices to disconnect from the grid.

We need to find that device!

Let's suppose it turns out to be a commonly-installed solar-inverter which is manufactured in the Far East.
Then let's imagine that it requires home-owners to allow remote monitoring across the internet so that data can be accessed via their mobile phone...

... but that the Manufacturer has used those internet connections to remotely apply a firmware upgrade which hasn't been checked for G98 compliancy.

Until we find what that type/model of inverter is, the problem will continue to be replicated across Britain.

Other legally-certified inverters of all sorts will be taken out of action every time one of those rogue inverters disobeys the rules.

That leaves us more susceptible to a Cascade Effect, in which embedded generation fails across a wide area.

Ignoring what is being posted here on this topic is not an option.

@l8again - it sounds like your DNO needs to be more pro-active. Who are they?
Instead of just attending on-site to look at a case of under/over-voltage, it's important to locate the equipment which isn't compliant.

... and that's before we start adding "Plug-In Solar" kits to the equation!

Posted by: @transparent

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Instead of just attending on-site to look at a case of under/over-voltage, it's important to locate the equipment which isn't compliant.

 

My high voltage ‘fault’ had nothing whatsoever to do with my solar inverter or Powerwall 3. My Powerwall 3 took the Grid offline at night with a voltage of 256VAC.

The DNO was happy that the matter could be resolved by tapping the upstream pole-mounted transformer. The DNO set a notional 240VAC to avoid any low-voltage problems further downstream in a rural area.

Posted by: @l8again

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The DNO was happy that the matter could be resolved by tapping the upstream pole-mounted transformer. The DNO set a notional 240VAC to avoid any low-voltage problems further downstream in a rural area.

And what will happen when the ENA approves a nationwide voltage reduction by reducing the 11kV output from all Primary substations?

Your DNO won't know whether they need to return to your PMT (pole-mounted transformer) and change the tap back again.
There's no monitoring on the vast majority of LV supplies or local substations.

The DNO is 'blind' to what happens at the far ends of rural routes.

If there ever is an under-voltage situation, the PW3 plus Gateway 2 will take my home off the grid. As far as doing anything else is concerned, the following saying comes to mind:

God, grant me the serenity to accept the things I cannot change, the courage to change the things I can, and the wisdom to know the difference."

Posted by: @l8again

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If there ever is an under-voltage situation, the PW3 plus Gateway 2 will take my home off the grid.

May I persuade you to see the effects of this from the viewpoint of the grid...

When an inverter disconnects itself from the grid, any export which it might have contributed is no longer available.
Consequently the voltage falls further.

That gets detected by another few inverters on the same local substation...
... which also disconnect under their G98 certification.

This happens rapidly because they are electronic devices.

The grid still has to meet the demand for those properties, and the additional call for power on the 11kV supply causes its voltage to fall.

And we can all see where this is heading!

The quotation is taken from the Factual Report on the Iberian Outage of 28th April 2025.

Small-scale embedded generation suffered a Cascade Effect, requiring the Spanish Grid to make up a sudden shortfall of power.

Historically the grid would've remained in full operation because of the inertia provided by generators using rotating turbines.

But when these are progressively being replaced by electricity from renewable sources, it leaves the grid more susceptible to an outage.

Once we start enjoying the financial benefits of exporting to the grid, we assume the social responsibility to continue doing so.
That's what should occur with a correct implementation of G98.
But we're now beginning to see chinks in that armour.

With the Powerwall 2 or 3 with a Gateway, grid voltage and frequency monitoring, and Grid disconnection is outwith the end user’s control.

The same logic applies to EVs and EVSEs. They will also respond to under/over-voltage situations by disconnecting from the Grid.