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Can DNO change a G99 export allowance once approved?

AndrewJ · 2026-07-07T12:30:27Z

I have a Solar/battery system with an approved G99 export limit of 3.68kW. I know that would/could be covered by a G98 but the installer and I were hoping for a lot more given the 10kW of panels installed. I experience an issue during summer where the export causes my voltage to spike over 254V and causes a PE fault with my Hypervolt charger: essentially I cannot charge my car at home during the day in summer. The DNO did come out and put a voltage meter on the supply and agreed it was spiking over the limit. This might normally be resolved by adjusting the transformer tap to reduce the voltage to the house but unfortunately the transformer is a fair distance away from the house and making changes would potentially negatively impact other households in the area so they can't do that. I did get a follow up call to say they would change the cable to my house to reduce the resistance and hopefully resolve the problem that way; they also said there is no timetable for the work but I shouldn't expect it to be done any time soon. That was last September and I've heard nothing since. Not charging at home during the day isn't really an issue and neither is the G99 limit as I can mostly manage clipping to keep it to a minimum. If I was to contact the DNO to find out what was happening, could they use it as a prompt to revisit the G99 limit and reduce it further? In some respects that also would resolve the problem if it was reduced to zero but would be a serious blow as even that small amount has allowed me to achieve a £0 energy bill in the last year. On a related note, is it possible to ask the DNO to relook at the G99 and increase the export allowance, again without them saying no and also reducing the current allowance? Basically, I don't want to rock the boat in respect to my export but it would be good to get the issue with the charger/supply cable resolved.

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Batpred

(@batpred)

Noble Member Member

Joined: 2 years ago

Posts: 1074

09/07/2026 9:50 am

Posted by: @andrewj

↑

... but as I said, I did get a call to say they wouldn’t upgrade the cable to my house at some point.

You had mentioned that they told you they would upgrade the cable at some point, but not very soon?

8kW Solis S6-EH1P8K-L-PLUS hybrid inverter; G99: 8kw export; 16kWh Seplos Fogstar battery; Ohme Home Pro EV charger; 100Amp head, HA lab on mini PC

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AndrewJ

(@andrewj)

Reputable Member Member

Joined: 1 year ago

Posts: 224

Topic starter 09/07/2026 10:00 am

Posted by: @batpred

↑

Posted by: @andrewj

↑

... but as I said, I did get a call to say they wouldn’t upgrade the cable to my house at some point.

You had mentioned that they told you they would upgrade the cable at some point, but not very soon?

Ah ha! People are paying attention 😀! My mistake, they said they would upgrade it. I’ll chase it and ask if switching phase would help.

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