Chewing The Fat..... "Volt-Drop"...

[UNG]

Out of interest, was there a lot of PV in the immediate area?
I had similar, and my suspicion was that in this upper class residential area a lot of early PV adopters without battery storage and lack of daytime loads was pushing the supply voltage up. I couldn’t prove it though.

You have guessed correctly
Seems to be the norm these days and it is becoming more difficult to avoid the inverter dropping out due to the high grid voltages although it could be good for selling battery storage

 

[UNG]

Having thought about the OP's conundrum there is a solution to the volt drop issue given on the EIC where there is the option to note "Departures from BS7671" if you can justify the reasoning for adopting a higher volt drop then the problem is technically solved, some may not see it as an ideal solution but as long as it can be deemed safe and does not present a danger I think it offers a solution to a common problem that occurs quite frequently
The only problem that may appear later on is when Mr DIY wants to add sockets or a heater and carries on regardless of the limitations of the installed supply

 

[binky]

You have guessed correctly
Seems to be the norm these days and it is becoming more difficult to avoid the inverter dropping out due to the high grid voltages although it could be good for selling battery storage

it's really an issue for the DNOs, if you are installing 16A limited systems, and it back feeds more than 30% of the local transformers capability, then it's the DNOs responsibility to do domething about it. Quite often they reset the transformer taps to a lower voltage. Sometimes they try to make out its the customers problem and try to get them to pay for an upgraded transformer, but by law, they cant stop you installing 16A limited systems. I've also had occasions where they have found their transformer taps weren't working correctly, so again a DNO issue.

 

[UNG]

it's really an issue for the DNOs, if you are installing 16A limited systems, and it back feeds more than 30% of the local transformers capability, then it's the DNOs responsibility to do domething about it. Quite often they reset the transformer taps to a lower voltage. Sometimes they try to make out its the customers problem and try to get them to pay for an upgraded transformer, but by law, they cant stop you installing 16A limited systems. I've also had occasions where they have found their transformer taps weren't working correctly, so again a DNO issue.

A lot of the issues and problems are caused by the older transformers that are still in service, they were never designed or built to tap down sufficiently to accommodate the PV revolution