DNO turning off systemsDno turning off systems

[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.

 

[moggy1968]

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.

hmmmnn, thats helpful then!

 

[Morgan keith]

We had a similar issue on a job but after speaking to the DNO nicely they came and measured the supply voltage at 251V and agreed they'd give all the property's supplied off that transformer 2 weeks notice of the power going off for a few hours and then came back and lowered the voltage. All works fine now.
Most importantly though, we did another job last week and were worried about the grid voltage as is was high but coincedently the customers had a power factor correction unit installed at the same time to 'lower their energy bills' and after that being installed the voltage went down from around 252V to just over 240V! Maybe this could be another solution? Although I'm not too clued up on PFC units, maybe someone else would know??

 

[MickF]

PFC's I think you'll find are the same as VO's a drop to only 240V consumer sided of the 'PFC' is not very good it should ideally be in the range 220V-230V ... if the 240V is supply side, then it's just coincidence. The PV will still need to be connected supply side of the 'PFC'

 

[Morgan keith]

PFC's I think you'll find are the same as VO's a drop to only 240V consumer sided of the 'PFC' is not very good it should ideally be in the range 220V-230V ... if the 240V is supply side, then it's just coincidence. The PV will still need to be connected supply side of the 'PFC'

Well the PFC was connected to the system in parallel (Protected by and MCB) and it lowered the supply voltage in the DB.
Coincence, maybe. But would have to be very coincedental

 

[Gavin A]

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.

I'd check ENA's position on this. The guy who's email addy is on the main page with all the guidance on it gave me a straightforward answer to a query inside a day last time I emailed him, just make sure you approach with a straightforward question.

after that there's Ofgem.

 

[xiaoneitie]

I've never noticed that. Have you asked OFGEM for their advice?

 

[SouthernSpark]

This may be a stupid question, but would installing a battery pack not help this situation? It would give the power somewhere locally to go and would save money in the long run. I know the outlay may be high initially, but if its a case of losing £30K or installing a large Ah Battery pack and using the power produced through the day, in the evenings, plus having the inverters working constantly so you can earn the maximum FIT, the benefits may be worthwhile.

On the other hand I am no engineer and have no idea whether this is actually feasable. Its just an option Im hoping someone on here could either say is possible or eliminate for whatever reason.

 

[st3ve]

First, I'm no expert, but I'm sure that I have read about problems with 2 inveretrs 'affecting each other' in something like the way you described.

I can't remember where, but I'll try to revisit some other sites I've been on in the hope of forwarding a link

 

[Worcester]

Here's an extract from the contents of a G59/2 Connection approval letter we got from UK Power Networks:

UK Power Networks (operations) Limited highlight that the maximum voltage limit for the network at which the generation is to be connected is 253/440V. If the generating plant causes the voltage to raise beyond this level it could ultimately result in the nuisance tripping of the generator sets or an unsafe condition on our distribution network. If the latter is found to be the case, we may require the customer to reduce the level of export or use our statutory powers to disconnect the generation plant altogether. If nuisance tripping of the generator sets occurs that the client or consumer finds unacceptable, this can be resolved by UK Power Networks (operations) Limited undertaking a tap change at the local distribution substation, if this is requested by the client, consumer, you, your company, the installer, electrical contractor or any other party, then it will be chargeable.

Definitely working to the letter of their powers as opposed to other DNO's that we often work with that are more flexible and understanding, givien the area they cover, perhaps UKPN's network has been hammered by so much wind generation, they are less open to variations?

Fortunately we just visited 15 sites within UKPN's area and never got an incoming voltage greater than 241V - perhaps just lucky!

 

[moggy1968]

what would they charge for retapping?

 

[Worcester]

Anything from a couple of hundred up to a few thousand, all depends, also in some areas, you'll find that the transformers are already on Tap 1, so would need to be replaced, that would be a siginicantly greater cost, and they don't like doing that becase of potential knock on effects if they decide to lower the output from the central transformers ...

 

[sedgy34]

I have recently proposed a 30 kw to the DNO they said max allowed on there network is 25 kw and if we want to install the 30kw it's going to cost £17000 to upgrade there equipment.

 

[Gary K]

I have recently proposed a 30 kw to the DNO they said max allowed on there network is 25 kw and if we want to install the 30kw it's going to cost £17000 to upgrade there equipment.

So if you install 25kw, whats stopping them asking you to disconnect at a later date because the input still causes problems in the future???

 

[moggy1968]

nothing it would appear, then you get sued and it's bye bye business, and all for margins at rock bottom at the moment!!

 

[sedgy34]

So if you install 25kw, whats stopping them asking you to disconnect at a later date because the input still causes problems in the future???

They have given us a confirmation letter for the 25 kw is acceptable

 

[SolarCity]

They have given us a confirmation letter for the 25 kw is acceptable

Fair enough, but there are suggestions that the DNO could subsequently ask for this system to be turned off IF they decide that the system is creating a voltage rise (it will) which the DNO decides is affecting the network.

 

[sedgy34]

The lenght of run back to the supply is 120 mtrs there could be volt drop on the ac side and if your concerned about that being switched off you wouldn't take on any job more than 10 kw

 

[SolarCity]

The lenght of run back to the supply is 120 mtrs there could be volt drop on the ac side and if your concerned about that being switched off you wouldn't take on any job more than 10 kw

It doesn't work like that. Your system will produce power at a voltage that is higher than the grid voltage regardless of the volt drop on the AC side.

I am concerned about systems being switched - all sizes of systems. I think it is a ludicrous state of affairs.

 

[sedgy34]

I will double check with DNO but there's no way after install its being switched off they will have to upgrade the equipment after its been vandalised!!! Lol

 

[Worcester]

They'll probab;y do what they do in germany - limit the export, hence SMA's article here Requirements for the PV system technology of the future and solutions by SMA

They have solutions that allow remote derating of the PV system over the grid by the germany equivalent of the DNO.

I'm sure it will come here, it's just a matter of time.