For others following this discussion, there's stuff happening behind the scenes which isn't being reported here.

A device which causes persistent over-voltage can't be left connected to the grid, especially when it's been proven to 'take down' other inverters, such as Tim's GivEnergy inverter. The situation is being looked into at a high level within NESO.

This is a typical scenario where the energy sector wants to engage with us ordinary consumers. They need our local knowledge, and accurate time-frames for when symptoms and faults manifested themselves.

Let's remember that the lower levels of the grid are not monitored.

Once the Primary substation feeds 11kV out to the scores of local substations which it supplies, there are no more voltage, current and frequency monitors which routinely record or send back data. Very few of the 550,000 local substations have ever had monitors installed alongside them.

Nor are Energy Suppliers required to retrieve data from Smart Meters which might alert the DNO of parameters which fall outside the statutory specifications.

@transparent I very much appreciated your input & followup on my specific issue as well as potential impacts elsewhere. Extremely interesting learning curve!

Yesterday i had a single overvoltage event. But that must be taken in context 

After the phase change I've gone from:
220 overvoltage events over the 19 days before the change (around 12 per day on average, with some days much worse),
to:
1 event on this day after around 17 consecutive days with none.

Other observations:
no sign of undervoltage events even with high draw. Occasionally 230v, mostly say 236v+
Night draw might include 7kw EV, 2.5kw battery, 3kw+ ASHP etc

It may be worth considering monitoring more closely during the winter to see if we are closer to undervoltage issues. If we are consistently well above the minimum but still getting close to max I guess it may be worth providing data to SSEN and ask them to gather their own data from a a datalogger... to consider tapping down the transformer?

I think I ought to go into greater detail on what is regarded as an Over-Volts fault.

When the DNO checks the LV supply, they use a 10-minute rolling average.

If the average supply voltage is always below 253v for any period of 10-minutes, then it is deemed to comply with the Electricity Safety, Quality and Continuity Regulations (ESQCR).

A G98 certified generation/export device works on much shorter time intervals.

It mustn't wait 10-mins before ceasing to export, but the speed with which it disconnects from the grid is a combination of how much over-voltage there is within a time interval.
Hence the settings which I illustrated here on page-1 of this topic.

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::

That means inverters may be taking themselves off-grid due to Over-Volts, even tho' the DNO declares the supply is within limits.

This isn't the problem which Tim is reporting here because his GivEnergy inverter is no longer disconnecting.

But I've written the above explanation because the different ways in which Over-Volts is defined might affect someone else's inverter, and they come across this topic in future.

The spreadsheet shows a clear improvement since the phase change. I will reduce my monitoring for now unless further issues arise.

ChatGPT has summarised its view:
https://chatgpt.com/s/t_6a45f299275481919926b36f87fb0b8a

Minor observation on ChatGPT: it counted 4 events after phase change. Actually 9. Nevertheless its still a 96% reduction in events. 

Posted by: @transparent

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Nor are Energy Suppliers required to retrieve data from Smart Meters which might alert the DNO of parameters which fall outside the statu

DNOs are Registered DCC Other Users and they can download voltage data from smart meters. There is no need for a supplier to be involved in the process. Some DNOs now use dynamic smart data to balance voltage and frequency are a higher level than the local transformer.

i had overvoltage events 3 years ago. My Powerwall repeatedly took my home off Grid until the voltage and frequency were within limits. Țesla provided me with a graph of the voltages that their system was seeing. I contacted the DNO (SPEN) and spent 10 minutes trying to get past their helpline who parroted the party line that smart meters are a supplier problem. 

I then emailed the Exec Team who confirmed that they could and had accessed my smart meter historical data which confirmed numerous over-voltage events but before they could do anything they would need to fit a calibrated energy recorder. A month later they tapped my pole transformer down to a notional 240V. 

Posted by: @l8again

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DNOs are Registered DCC Other Users and they can download voltage data from smart meters.

No; they aren't permitted data from individual Smart Meters.

DNOs only receive averaged/aggregated Smart Meter data for a given local substation feed for privacy reasons.
And if a transformer feed supplies less than 4 houses, they can't see that data at all for the same reason.

This was discussed with a senior engineer at an NGED workshop in Exeter yesterday (1st July).

This is a tricky issue because NGED is reducing LV supplies from the nominal 240v to 236v, and might be able to go lower.
This is being done by adjusting taps at Primary Substations to reduce voltage on the 11kV routes, rather than visiting tens of thousands of local substations(!)

Voltage reduction allows greater headroom for more export from domestic solar. Houses which would otherwise have been allocated the usual 3.68kW (16A) may now be offered between 4kW - 6kW.

However difficulties arise on the long rural 11kV routes. Older/thinner cables can exhibit considerable voltage drop at the end of the line, especially during periods of high demand.

Since these often have just a farm and a couple of cottages supplied by a pole-mounted transformer, DNOs don't have sight of what happens.

A small proportion of ground-mounted local substations are indeed equipped with monitoring systems such as those from Lucy Electrics.

But the vast majority of the distribution grid routes are rural, with 11kV lines often running 20km+
Since they are connected to same Primary Transformers which feed substations in the nearest town, you can't just drop the line voltage by 5% and hope everything will be ok at the ends of the rural lines.

It was three years ago but I recall that the SPEN Regional Distribution Manager sent me a copy of the 30 minute voltage data downloaded from my smart meter. They also sent me a copy of their DCC approval to access this data. He said that it confirmed that there was a overvoltage issue but they were unable to use this information as it came from a standard meter. They then fitted a calibrated voltage recorder.

You are right that tapping a pole transformer in one location has a downstream effect. Before doing any work, SPEN had to send out 250 letters informing residents of a power break of up to 2 hours. In the end it took them less than an hour to move between 3 pole transformers to confirm that all voltages would be within limits. This is why my local transformer was left at 240V.

This 2024 trial indicates that DNOs are collecting voltage data from individual smart meters:

https://www.northernpowergrid.com/innovation/projects/beet-boston-spa-energy-efficiency-trial

I suspect that they are not doing it routinely on all smart meters even though SPEN appears to confirm on its website that they are taking daily consumption data downloads.

Thanks for that slightly alarming information @l8again 

I too am registered as an "Other Party" and a Member of the SEC, so I'm noting the differing interpretations of the SEC regulations by different DNOs!

This is an ethical issue, and one which should be brought to the attention of our elected representatives. Many Councils are involved in the creation of the Regional Energy Strategic Plan (RESPs) for the 11 regions of Britain, and these are relevant matters which they will want to discuss with NESO.

At the NGED workshop in Exeter, which I just mentioned above, the person sat to my left was the Local Authority representative for the area in which @tim441 lives! She was taking part in the discussions with NGEDs senior engineer, and will have heard his unequivocal explanation of what a DNO may and may not do to obtain and use Smart Meter data.

By the time I hit Add Reply on this post, Tim will already be sharpening his quill and asking his Council to verify the legal & ethical position!

I can see benefits in both directions, but the present state of Privacy Laws, incl GDPR and the Priority Services Register, must be adhered to.

Interestingly, NGED asked attendees at Wednesday's workshop if they should have greater powers to provide resilience to society, perhaps by prioritising backup electricity supplies to community centres. Those could serve as Warm Spaces in winter, Air-conditioned spaces in summer, and offer cooked meals during prolonged outages.

The responses we gave them showed that we were not in favour of moving such social oversight from Councils to a for-profit commercial company. It is our Councils who already know how their local area works, where are the vulnerable households, and the level of urgency required in response to an emergency. They already have robust privacy rules, and are very unlikely to share any such information with their DNO.

As I understand the regulatory position, a DNO may not have access to energy data for an individual household.

Yes, I'm aware that DESNZ will disagree with what I've just stated.

They have spent a couple of years creating a secure database system which combines Smart Meter data, the identity of the householder and a certain level of information regarding their energy account with their supplier. That SSES database will be accessed under licence terms for 3rd-parties to switch off in-home devices remotely, during times of high demand. This will operate using encrypted commands, sent over the internet, rather than the secure messaging pathways which are already embedded in Smart Meters.

@transparent By asking SPEN to access my smart meter voltage data it could be argued that I gave them permission to do so - as is the case with third-party access such as BRIGHT.

Just to reinforce the fact that some DNOs are accessing voltage data from individual smart meters this is further information on the Northern Grid BEET Trial

How will my smart meter data be kept safe?

We take your data privacy seriously. BEET will not use energy ‘consumption’ data which, under

GDPR, is covered by our Data Privacy Plan, see northernpowergrid.com/privacy-policy. We will

only use voltage readings, which don’t tell us about your personal energy consumption and don’t

give insight into your personal data. All the BEET-Box will see is the ‘big picture’ of voltage usage

across the network.

As far as 30 minute consumption data is concerned this is what is available online

• Data Collection via DCC: SPEN automatically requests routine, half-hourly meter readings from households with a smart meter via the Data Communications Company (DCC). 
• Disaggregated Consumption: The data SPEN accesses is disaggregated. It is used to generate total monthly consumption figures, monthly minimum and maximum demand, and aggregated daily profiles for the local electrical feeder you are connected to .
• Strict Privacy Rules: While this data is not completely anonymized when received by SPEN , it is heavily encrypted in transit and bound by strict Smart Energy Code obligations and an approved Ofgem Data Privacy Plan.
• Network Management: SPEN uses this consumption data to support data analytics and to plan, operate, and manage the electricity network safely and efficiently.

I confess that I don't buy into the argument that someone knowing my power consumption poses any risk. I can walk down my street and make an informed guess about who is in; out or away without the need for smart meter access.