DNO turning off systemsDno turning off systems

[Gavin A]

I worked as an engineer for a DNO for thirty-five years. Last year I had a 3.12kW system installed. All worked fine until mid summer when I noticed several trips taking place around lunchtime at peak production. I still had a calibrated voltage tester and my incoming volts with pv off production was around 250-252volts. I rang the local office as a customer and explained I wanted the situation logging. I actually knew that we had a 33/11kv primary transformer out for some work and the tap changer was on fixed tap due to a problem. This situation went on for about a week with tripping at peak production times when the DNO network was restored the problem still caried on.

I again contacted the DNO and this time explained the situation 'officially' Needless to say the lads that came round knew me and they admitted they knew very little about the voltage issues regarding PV production. They checked volts at the local sub-station (252v) and again at my house again just about on limits. We had a bit of a training session, tea, biscuits and a chat and they agreed volts were a bit high.
Next day they backfed sub-station lowered the tap and house volts incoming are now 240v with PV off.
All I can say to help is offer tea, biscuits and explain your point honestly. I understand they are flooded with these type of issues now, so I think I was lucky. I have no doubt they are now sticking to the terms and conditions to save money on network reinforcement.

Also, if you're really good as an installer then DNO engineer will then turn round and get you to install a system on their house... and that DNO engineer will then become the DNO's expert for solar PV engineering questions for every engineer for miles around

 

[Earthstore]

I didn't think you could use VO's in that way - to feed power back to the grid through them.

Gavin, you are correct, you can not feed PV back through a VO, it has to be connected before the VO, we covered this a while ago and one member on here (no names) is now the proud owner of one of these units, purely because they had installed one and tried to feed the PV back through it.:38:

 

[TedM]

Thats why, even under G83, you are required to notify the DNO if there are multiple installations in the same area. How many do? none I suspect, so stand by!

The requirement to pre-notify is only if the multiple PV systems are installed by the same company. If company A installs at house number 2 and company B installs at number 4 there is no need to pre-notify.

If company A does a single install at number 2 and then comes back 2 years later to install at number 4 then they will need to pre-notify. G83/1-1 Stage 2 has never made this particularly clear but G83/2 does.

 

[moggy1968]

seen it done though, no notification, more than 8 on the same street.

 

[SolarCity]

If company A does a single install at number 2 and then comes back 2 years later to install at number 4 then they will need to pre-notify. G83/1-1 Stage 2 has never made this particularly clear but G83/2 does.

I thought you only had to pre-notify if the two installs were carried out at the same time?

 

[sedgy34]

DNO tell me they are notified anyway by the supplier when fit application goes in.

 

[SolarCity]

DNO tell me they are notified anyway by the supplier when fit application goes in.

Really? I'm surprised by that.

They will still need notifying anyway - they need G83 certificate, completed forms and wiring diagram.

 

[moggy1968]

isn't that shutting the gate after the horse has bolted though?
My understanding is that in the case of multiple installations they should be notified before installation.
Although they can still ask you to turn it off after if you've had prior agreement you would have a slightly bigger stick to beat them with. Leave it until after and the ball is very much in their court

 

[SolarCity]

Although they can still ask you to turn it off after if you've had prior agreement you would have a slightly bigger stick to beat them with.

I am utterly staggered that they can do this after permission has been granted for its connection - raising the voltage is not a fault, it is design.

 

[TedM]

I thought you only had to pre-notify if the two installs were carried out at the same time?

As I say G83/1-1 Stage 2 doesn't make it clear but the wording in G83/2 is less ambiguous.

 

[tottenham steve]

i would be looking at voltage optimisation to see if that would help the over voltage,gonna be alot cheaper

We have tried voltage optimization (VPhase).It is against regs as the inverter is supposed to be able to monitor the true grid volts, but it doesnt work any way because as soon as power is fed through the optimiser in reverse, its goes into bypass mode and your no better off.
Going to speak to the DNO today, fingers crossed everone!!

 

[Brian-s]

Thats why, even under G83, you are required to notify the DNO if there are multiple installations in the same area. How many do? none I suspect, so stand by!

How can you tell? on an East/West road half of the possible installations will be hidden from from view.

 

[tottenham steve]

How can you tell? on an East/West road half of the possible installations will be hidden from from view.

UPDATE:

Just spoken to the DNO (uk Power networks). They say it is there policy to not change the voltage settings if they are within guidlines. They will give permission to connect to the gride but if the voltage rises above guidlines they will instruct you to disconnect. Apparently they do not bother to check that it is safe to connect to the grid, they just give permision and then screw the customer if it causes a problem.

 

[TedM]

How can you tell? on an East/West road half of the possible installations will be hidden from from view.

That's one reason why it only applies to installs that you have done yourself. You are presumed to be able to remember doing them all.

 

[Earthstore]

Steve, I have asked you some questions that could help you, but you have not answered
Whoever installed the V phase should have read the intructions, and they should also know that you can not back feed a voltage optimiser.
If you could get your inverter to stay in then a voltage optimiser would help your situation, but not the 20A V phase though.