,

@tim441

I believe inverters are required to trip on over voltage, so it may not be a fault.  If the incoming grid voltage is too high they will presumably do so notwithstanding that there is capacity in the battery. @transparent may be able to clarify.  Is there a lot of solar where you are? 

Posted by: @tim441

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Afaik Gen1 Hy5.0 has a max voltage of 253v before tripping? (DNO 230v +10%).
My logs on first review show regular 256 -260v
I contacted DNO to see if they can be persuaded to show some interest.
Just wondered if any other suggestions to help diagnose or cure?

It sounds like you're on the right track...
but I'm not yet convinced that high-volts is the sole cause.

May I give you (and other readers) some background info:

The Designated Voltage is indeed 230v in GB, and not the 240v we're used to receiving.

The mains (single-phase) voltage should be between 216.4v – 253v.

To ensure this, a DNO engineer would take a measurement over several minutes, and ignore transient spikes.

There is no harsh implementation of the 253v figure by DNOs.

Even so, to pass the G98 test parameters, a generation device (inverter) may not itself export to the grid above 253v.
That's basic common sense, and I'll assume we can all accept that!

If the high voltage is due to some other device, perhaps at a neighbouring property, the inverter isn't immediately required to cease operating, (ie detach itself from the grid).

There is a time parameter which comes into play. An inverter will accept a wider voltage deviation before disconnecting, provided it is of short duration. Typically it might look like this, where Vφ is the designated line voltage of 230v::

This wider envelope prevents spurious tripping/disconnection due to spikes and surges on the line caused by devices at nearby houses switching on/off. However, device manufacturers may implement a tighter voltage envelope if an under- or over-voltage might cause damage to their own equipment.

Once an inverter does 'disconnect' due to line conditions, it may not reconnect itself to the grid until a randomised period of time after it detects the grid is once more within operational specification.

That randomised period will be around a minute. It is this characteristic which is most likely contributing to you losing so much solar generation.

If the GivEnergy inverter sees the parameters as being within-spec for 59secs, and then there's an over-voltage or a frequency shift, it will start counting its randomised interval all over again.

Posted by: @tim441

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My logs on first review show regular 256 -260v

From where are you obtaining these logs?

Is this a GivEnergy App?

If so, is it directly obtaining that data from the inverter (via Bluetooth perhaps)?
Or does it first get sent to a server in The Cloud by the inverter, and the App retrieves that data a few seconds later?

I have particular interest in this subject matter because:

a. GB is about to reduce the normal 240v line voltage to the Designated Voltage of 230v

b. The lower voltages of the Distribution Grid are not routinely monitored by the DNOs. Of the 550,000 local substations, less than 0.01% will have ever had monitoring apparatus installed.

c. I have designed my own voltage monitors to obtain either single-phase or 3ph logging of LV (that's the 440v - 240v level).

Some of my monitors are currently undergoing field testing. Using that data and their position on the grid, we can also 'see' voltage deviations at 11kV and above.

That data-stream has the potential to detect (and even predict) when there is unused capacity on the 11kV and LV grid levels.
So instead of raising bills to pay for major grid upgrades, we can time-slice that available capacity.
It could be a 'trigger' which tells a storage battery to re-charge from the grid, for example.

We're not going into the detail here of how that would operate. But I hope I'm giving you sufficient insight as to why I'm interested in the detail of what you're discovering at your home.

Could you please tell me who is your DNO, and your approximate geographical location?

Thanks.

Many thanks for the helpful and educational inputs!

I'm in Somerset... SSEN is DNO. Its a small village. Transformers were updated under 30 years ago (28?). Perhaps higher solar than normal(?). 

App is from GivEnergy. It measures both Grid and Inverter voltages - i assume relevant. Both exceed 253v at times. Inverter more.

The visiting engineer was surprisingly helpful and interested in understanding the problem as well as finding a solution.

I hasten to add that I have no special knowledge/expertise.

That's useful information @tim441

I would like to be kept more in the loop on this issue.... ideally in direct communication with the Area Manager foe your part of SSEs region.

You and I are both in the same RESP. GB is divided into eleven Regional Energy Strategic Plan (RESP) areas, as detailed in this Decision Notice from Ofgem published in April 2025.

The eleven Regions have been defined by having equal population, rather than any scientific characteristics based on energy. That's going to make it much more difficult to arrive at a single strategic plan which covers an entire RESP.

It also means that the South West Region is mostly covered by National Grid Electricity Distribution as the DNO, but there is part of SSE's licence area added in to make the numbers balance. 🤦

The following map is a composite from four sources, which should help to make your position clearer:

The pink area is the South West RESP region.

The cross-hatched area to the east is where SSE holds the DNO Licence from Ofgem.

The brown area is that portion of East Somerset where you live.

Your SSE Engineer will need to investigate what level on the Distribution Grid is showing similar over-voltage to that which you've reported from the GivEnergy App.

That will allow them to change the taps on the right transformer:

The South West RESP participants are about to have the first ever in-person forum at Taunton on 23rd June.

Up until now, those with an interest in having a say in the Strategic Energy Plan for their region have only been addressed in online Webinars, presented by NESO staff. None of us know who the others are, nor what level of knowledge/expertise is present amongst the group.

Nor can we tell how well acquainted are NESO's own staff with insights into relevant local issues.

For example, how much are they aware of the effect on the grid when Hinkley-C comes on-stream in 2028?

Will that electricity from Hinkley 'swamp' the available capacity on the 400kV Transmission grid, effectively requiring less generation to be accepted from Devon & Cornwall?

It's very relevant that your 'brown coloured' area of this RESP region has reported an instance of over-voltage. If that is indeed from excess solar generation, then it needs to be curtailed. NGED operate a mechanism called Active Network Management to achieve that in the West Country. But I don't yet know if SSE use the same dedicated radio-network, or perhaps a different mechanism with a similar effect.

Ideally I'd like to see both yourself and your SSE Area Manager at the NESO workshop in 3-weeks time. Spaces are limited, but it's important to glean the right inputs before trying to discuss a common strategy!

@transparent thats very interesting! 

I have booked a ticket and will try and do some pre-education. I will attend in personal capacity as well as for our Parish Council.

When the engineer returns next Wed I will mention the forum to him to see if an Area Manager will attend.

I think i was lucky to get a senior overvoltage guy who happened to be nearby and picked up the case. So am optimistic that it will be properly followed up. 

I don't know if the fact we're on the borders of SSEN & NG means their systems play well together?

I will PM my contact info 

Posted by: @tim441

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App is from GivEnergy. It measures both Grid and Inverter voltages - i assume relevant. Both exceed 253v at times. Inverter more.

I think we need a bit deeper discussion on that observation.

A. Is the App getting that data direct from the GivEnergy hardware in your home?

Or does the GivEnergy inverter send it elsewhere via the internet,
and the App picks it up from there?

Ie: if your home router was inactived, do you still get data on the App?

B: To export power to the grid, an inverter raises its voltage with respect to the incoming mains.

The current then flows from the inverter to the grid.

Thus, if the inverter itself has just raised the mains voltage because it's busy exporting, it cannot simultaneously take a reading of grid-voltage with any accuracy.

The LV voltage supplied to homes varies all over the place due to solar being exported by you and your neighbours, or additional demand being made by others on the same local substation.

Ignore the red line on the timeline below.
The other three monitors have been placed on different local substations, all of which are supplied with 11kV from the same Primary:

When solar export to the grid increases, the amount of current taken from the 11kV supply by your local substation will fall. But it doesn't do so evenly because there will invariably be more houses exporting to the grid on one phase than the others.

Several monitors are required at different places on the grid in an area in order to reveal the picture of what's happening.

Your in-home GivEnergy inverter can't do that. It only sees what's happening at the incomer to your Smart Meter.
I don't see how that inverter is able to provide voltage measurements of the grid without 'knowing' what else is going on around it.

@transparent as you probably know GivEnergy entered administration in April impacting support etc.

The software side has continued by introducing a monthly charge (Axle will pay that if joining them).

Some of key support & software people are now at Predbat.

The data is sent via a wifi dongle to the cloud 

https://givenergy.cloud/login  

Some data is then available via an app. I will add screenshots shortly - in case it helps.

Fyi here is a pic of the overvoltage monitor

Thanks for that info.

Yes, I'm well aware that GivEnergy is in administration.

If your ongoing access to data is implemented via Axle, then it's most likely that the App is receiving that from a server in the cloud.
Therefore I'll assume that you can't obtain voltage data directly from the inverter.

Can you see what the PM1000 unit is recording, or is that simply storing data until SSE come back and plug it into a laptop?

Looking at the charts you'd posted here, if the inverter is exporting almost 5kW at a time when it thinks the grid voltage is almost 260v, then my first observation is that the inverter is at fault for making that increase above 253v.

But I still have too little data to reach a conclusion.

Does the column labelled "Inverter output power" tell me the SUM of what's being consumed in the home PLUS what's being exported?

And what export limit did SSE agree to when that inverter was evaluated via the G99 Application?

As I now have your post-code (thank you) I've been looking through SSE's in-house data.

The town 5km east from you has a Primary Substation which connects to the 400kV National Grid at Mannington in Dorset.

The centre of habitation 5km west from you has a Primary substation supplied from Axminster.

Whilst both are Grid Supply Points on the southern section of the Transmission Grid, I wouldn't expect their supply characteristics to be the same. The 132kV connection from Mannington is entirely within SSE's area, whilst Axminster is in NGED's patch until just short of the BSP at Yeovil. The 132kV grid resources are being operated by different companies.

Both GSPs are 'within' the B13 Boundary which defines the major constraint on generation in the West Country.

I'm about email SSE to request more insight.

@transparent 

I don't think Axle have any involvement other than paying my subscription fee. The data would be provided the same way whether i pay the fee or Axle does. It is via a GivEnergy cloud server.

I can't see PM1000 data

Afaik inverter output will include the sum of all house consumption plus exports. However I'm unsure how that is picked up and accuracy. e.g. Is it CT clamps? I am pretty sure its incomplete.

I keep a spreadsheet on monthly figures from GivEnergy/Meter/Octopus. They don't fully tie up! For one thing i have a small second pv solar setup on a Solaredge inverter.

In 2025 i measured 

GivEnergy total usage 10769kwh

GivEnergy grid import 11961kwh

Octopus metered import 15800kwh billed

GivEnergy grid export 5875kwh

Octopus grid export 7505kwh billed 

Solaredge metered prod 1714kwh

============

I have measurements for ASHP & EV within those numbers

My G99 limit is 6kw. I think with our orientation and pitch we may get a small amount of clipping. But not much.

@tim441  - I've been granted access to a deeper level of SSE's mapping data.
For obvious security and privacy reasons I'm not posting this here on an open forum!

There is a 50kVA pole-mounted transformer supplying you and your neighbours. One dwelling is north of that 'local substation' and the others are south.

The data appears to show that the substation can be supplied at 11kV from either the Primary west or east of you, or both simultaneously.

That's only possible if both of those Primaries are in the same Vector Group, or there are 'fuses'/links which create an 'Open'.

I'll need to spend a lot longer looking through this data-set to see if I can get it to show Opens.

@transparent many thanks for your interest and for following up.

The engineer returned this am to remove the device. I had hoped it would stay a bit longer as the last week has generally been mild with little sunshine. So probably below average swings in demand or solar prod etc.

The data showed voltage varied between 233 abd 252.9v. So within limits- just!

However he has arranged for the pole team one day soon to

1. Fix/clip cables at top of pole that are loose and potentially moving in wind etc

2. Swap the phases so we are on the phase that supplies just 2 houses near us. He thinks that might operate at a lower voltage and have less swings.

He did say he could consider turning the voltage down at the transformer but was concerned that might cause under-voltage supply in winter if demand is high. Sounds fair comment?

But he was also open to a further report if things don't improve after pole visit. At which point he will reconsider options