Over voltage

[Exfarmer]

anyone had issues with this. I am starting to have issues on one site, we are currently having board investigate, but the feed back from their personell doing the investigation does not sound good
They appear to be blaming me for putting too much into the grid.
Obviously I am not feeding any more since we placed the install 5 years ago .
3 years ago a neighbour was given permission to 30 kw install solar on his roof and we believe issues started then.
We have had inverters failing at odd times since, 2 out of 5 replaced under warrantty .
During a routine inspection on the 2nd. Of this month, I noticed the inverters were going ape every time the sun came out, it was one of thise days with a lot of cloud but odd clearing and a lot of sun then.
As the sun came out the inverters would immediately rise to about 40kw production when at least one and several times up to 3 dropped out.
After 2 or 3 minutes they came back in. Production then as soon as all five cut in immediately 2 or 3 would drop out again.
They were all reading over voltage.
In fact they have given readings of up to 507 volts ( 3 phase)
The board man who saw this horrified! Anything over 460 apparently is a complete no no.
They are currently monitoring the line voltage, but as said before they were suggesting we need to change, or reduce our equipment,any one else had this problem

The panels feed chicken sheds, i believe the issue was created by both the sheds our panels are on and the other sheds, again poultry, were empty meaning consumption was near zero, due to the cycles of production coming together, which does not happen regularly.
I would appreciate any comments from anyone else who has had this issue, whether publicly or private.

 

[Deereone]

Yes, I've had similar problems. There is a legal limit to the number of volts you are allowed to feed in. If your neighbours unit (or the grid) is set to a higher voltage than yours, you will not be able to export.
I have had 29 yes! 29 replacement inverters. The current ones have lasted much longer than all the previous ones. The issue was the IP rating

 

[Exfarmer]

Surely if you have G59 agreement the board ( I call them the board but actually mean the District Network Operator or DNO) have a duty to ensure line levels are below that which means you can export.
The inverters job is to keep the level of power up to the point at which it will feed into the grid. This as we know must not be more than 253 volts per phase.
( for those not in the know, voltage will "flow" from the higher to lower just like the pressure of water in a pipe)

 

[DC21]

How big is your array? Different rules apply for different sizes.

 

[Exfarmer]

our array is 50Kw

 

[sjt01]

Occasionally our line voltage to N goes over 253, the legal limit, and our G59 relay trips out. Usually seems to be that the taps have been changed on a transformer somewhere to compensate for reported low voltage, without taking into account other connections that might be high. Complain, keep a record of the complaint references, and after a while it might get fixed.

 

[DC21]

Your equipment should be compliant with G59, this should mean it will automatically disconnected if the voltage exceeds the maximum allowed. In simple terms you can go upto 10% over voltage, so 264V phase to neutral.

 

[f0ster]

this scenario is all to common now, I have a customer who is getting 253V per phase and of course the inverter keeps tripping out every few mins, so he is only generating a fraction of the KW he should be, there is a solar farm not far from him which is boosting up the line voltage to this level. the dno has been out to monitor it for a week but it was not very sunny when they came which gave lower readings than normal, they are legally obliged to ensure the line voltage is below 253V per phase. I have got the software for this inverter so I am going to raise the upper voltage limit a little because the dno will not do anything, one of the brands of inverter we have used has an interesting function, when you select the country code it also gives the voltage upper and lower limits for each country, it turns out that selecting Germany gives a lot higher upper voltage limit, you are stuck between a rock and a hard place, the dno will not do anything and you cannot generate much kw due to grid voltage being far too high. if the swa cable feeding the inverters has too much volt drop this can also cause this high voltage tripping out.

 

[sjt01]

this scenario is all to common now, I have a customer who is getting 253V per phase and of course the inverter keeps tripping out every few mins, so he is only generating a fraction of the KW he should be, there is a solar farm not far from him which is boosting up the line voltage to this level. the dno has been out to monitor it for a week but it was not very sunny when they came which gave lower readings than normal, they are legally obliged to ensure the line voltage is below 253V per phase. I have got the software for this inverter so I am going to raise the upper voltage limit a little because the dno will not do anything, one of the brands of inverter we have used has an interesting function, when you select the country code it also gives the voltage upper and lower limits for each country, it turns out that selecting Germany gives a lot higher upper voltage limit, you are stuck between a rock and a hard place, the dno will not do anything and you cannot generate much kw due to grid voltage being far too high. if the swa cable feeding the inverters has too much volt drop this can also cause this high voltage tripping out.

If your voltage is outside the 218-253 volts phase to neutral band, the DNO is breaking the law. Complain, keep a record and if it persists complain to the regulator OFGEM

 

[Exfarmer]

Interesting comments, I wonder if we should consider how we can use more on site when the sheds are empty. Possibly boiling water for sterilisation.

 

[Wombat]

same here, DNO have said they are a volt over but will do it in their time and any damage is ours to stand. Generated FA since April as we daren't turn anything on.

 

[f0ster]

see if it will let you select a different country code, this one we were dealing with allowed it (with password access, default usually 1234 or 0000)

 

[Exfarmer]

We have now had the input voltage monitored for a week. The UKPN man was shocked to discover the monitoring equipment had thrown up some huge vagaries in the voltage.
The monitoring equipment was placed on the line side of the meter

The individual phases showed fluctuations in the line voltage from 170 - 300 volts! This was independent of whether the panels were turned on or not.
The phases also revealed one phase was consistently 10+ volts higher than the other two.
Not sure what this has done to my equipment or all the other machinery on site.
He did want to do a full load test turning all the equipment on but the owner refused to allow it as he has currently got £150 K of. Chickens in the sheds and he was worried about turning all the fans on. So we will shall have to wait for that.
The UKPN guy was not happy when he heard the sums quoted for stock and equipment!

 

[akaPABLO01]

They probably need to service their sub. Can’t see dropping site tranny tap down would rectify volt fluctuation on this scale.

 

[Exfarmer]

Apparently according to the UKPN man they have a similar problem a few miles away which is definitely on completely different line, where they have been battling for a year with no result.
I know absolutely nothing of the electrics upstream of the meter, so interested in any comments.

 

[sjt01]

The individual phases showed fluctuations in the line voltage from 170 - 300 volts!

That is horrendous. Surprised the electrical retailers in Bury St Eds are not doing record breaking sales in the area. When we were running at 253-254 our washing machine caught fire. Luckily we were in the house of the whole lot would have burnt down. I suspect much consumer electrical stuff is designed for 230 v, with very little tolerance and no testing at the extremes.

 

[akaPABLO01]

Apparently according to the UKPN man they have a similar problem a few miles away which is definitely on completely different line, where they have been battling for a year with no result.
I know absolutely nothing of the electrics upstream of the meter, so interested in any comments.

Have you checked the solar electric cert on AC voltage test?

 

[Exfarmer]

Have you checked the solar electric cert on AC voltage test?

Sorry I dont understand.
Initially the attitude of the UKPN guy was that it was probably our PV causing the problem, but they tested the system for 2 days with the PV turned off, then they had 5 days with it on.
The PV made very little difference

 

[akaPABLO01]

Sorry I dont understand.
Initially the attitude of the UKPN guy was that it was probably our PV causing the problem, but they tested the system for 2 days with the PV turned off, then they had 5 days with it on.
The PV made very little difference

A lot of renewable energy is entering the grid which the DNO cannot mix quick enough then is my guess.

I’ve a hydro plant a mile away from an install and it boosts voltage from 244 to 260/270 early afternoon which shuts the inverter g59 for several minutes. I’ve not looked at an optimiser as they’re just like g59 and shut down the inverters until voltage stabilises.
I’ve thought about contacting the DNO to see if they could do anything and I think I’ll just get the same response for a lot of effort.

It’s not causing much loss but still impacts on generation some few %. Albeit not enough data has been collected and would like at least a year.

That’s if the sub can worked for a fix.

 

[Old earwig]

We had this sort of problem a few years back and it turned out to be back up the supply line. There was an auto tap changer on the 33Kv to 11Kv tranny that would both get stuck or oscillate.