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Author Topic: G83  (Read 30350 times)
marshman
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« Reply #15 on: July 18, 2010, 12:33:55 PM »

[
[/quote]

The DNO should be able to change the tapping on the transformer to give a lower voltage.  Often the voltage was set at the top end of the range if a lot of electrical power was going to be used.  E.g milking machines at a farm.

[/quote]
Yes they should, but they are reluctant to do so without lots of investigation. They have monitored one of the other phases and this is not as high. The EDF engineer that  fitted the logging/monitoring box was aware I was feeding back into the grid - he wondered where 10.5amps was coming from. But he said his boss has said allow up to another 4V on top of the upper limit (253V) to allow for the grid tied inverters!! He didn't think they had a requirement to keep to 253V if there was a generator feeding back !!!  He did admit that the whole issue of microgeneration was still evolving and that they as the DNO didn't really have much to do with it at the moment - but they were aware of it!!

Roger


Ted,

I will phone the installer on Monday and ask the question.

Thanks

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Philip R
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« Reply #16 on: November 19, 2010, 11:05:38 PM »

Well done Ted,

You are very well informed and your articles concise, explicit and timely. You will get an applause mark from me.

Regards, Philip.
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Philip R
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« Reply #17 on: November 19, 2010, 11:23:23 PM »

In reponse to Marshmans comments.

When you said the volts went upto 257V,
The system voltage you see is partly due to variances on the supergrid system. Yes, it swings about during the day as voltage gradients down a power line are used to shift real and reactive power.  Local variations should be partly compensated by tap changing or VAr control at the bulk supply point by NGC or DNO. Finally, your local 11kV/415 transformer should have either an off load tap changer or a link box with tappings above and below nominal values.
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peterpiper
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« Reply #18 on: January 14, 2011, 12:39:33 PM »

Whats the position if you have one system connected under G83 then want to add a second G83 of a different technology eg Hydro 1kW then Solar 3.6kW.

As I understand: Solar PV systems under 16A per phase (i.e under 3.68kWp) come under engineering recomendation G.83/1. Solar PV systems installed under G.83/1 can be installed without prior notice to the DNO, with the DNO being informed afterwards (within 30 days).

So the DNO will have been informed of the first installation, but it seems that DNO expects to be told after installing the second system. Is that the case or do the rules say anything different somewhere.

In our particular case we are fed overhead from a transformer 150m away, which also feeds one other house. It's fed single phase HV for about 1km. The transformer and HV line were installed 5 years ago, it's much larger than the old transformer, which was much further away and fed 5 properties, replaced due to low voltage issues.

SSO is Scottish Hydro, local MCS people say getting above 16A with them is hard.

At the moment we are deciding on PV system, may want to add hydro 500-1kW, later so what maximum PV size to stay G83?
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freddyuk
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« Reply #19 on: January 16, 2011, 12:42:17 PM »

I had a conversation with a guy who just completed his PV course prior to his first qualifying installation.
I asked him about the G83 limit as I think it is 16 amps out of the inverter which should be the defining measurement although I would prefer the 4kw installed collector capacity. He started scratching his head as they had not really defined this but he did assure me that the accepted voltage should be based on 240 volts.
That is 3840 kw.

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Ted
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« Reply #20 on: January 16, 2011, 03:11:25 PM »

"16 A per phase, single or multiple phase, 230/400 V ac"


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GavinA
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« Reply #21 on: January 19, 2011, 12:21:26 AM »

Whats the position if you have one system connected under G83 then want to add a second G83 of a different technology eg Hydro 1kW then Solar 3.6kW.

As I understand: Solar PV systems under 16A per phase (i.e under 3.68kWp) come under engineering recomendation G.83/1. Solar PV systems installed under G.83/1 can be installed without prior notice to the DNO, with the DNO being informed afterwards (within 30 days).

So the DNO will have been informed of the first installation, but it seems that DNO expects to be told after installing the second system. Is that the case or do the rules say anything different somewhere.

In our particular case we are fed overhead from a transformer 150m away, which also feeds one other house. It's fed single phase HV for about 1km. The transformer and HV line were installed 5 years ago, it's much larger than the old transformer, which was much further away and fed 5 properties, replaced due to low voltage issues.

SSO is Scottish Hydro, local MCS people say getting above 16A with them is hard.

At the moment we are deciding on PV system, may want to add hydro 500-1kW, later so what maximum PV size to stay G83?

I'll take this one...

the rules would seem to indicate that you need to notify the dno in advance and gain permission / check that the transformer can take it / pay for an upgrade if needed, but then still install to G83 standards on each sub 16amp microgenerator. At least in our experience with SSE (the scottish branch), though they absolutely insisted on us also installing a G59 control box between both g83 inverters and the grid connection as an additional control measure / safety net.

this was 6kW wind pre-existing plus 3kWp solar PV, so they may look more favourably on it if it's only a kW of hydro.

if that's clear as mud still I apologise, I gave up arguing and installed the extra control box as I couldn't find anyone who's role it was to act as an independent arbitrator between the DNO & us, so it seems the decision is based on the whim of the DNO in question rather than any actual guidance or legislation.
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jamesingram
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« Reply #22 on: July 19, 2011, 10:01:20 PM »

G83/1-1 is ok for systems up to 3.68kW ( ok so this is inverter peak ac rating not peak panel size, just found out on DNO thread , good news for me )
I've heard 3.84kW mentioned ( 240Vac being used not 230Vac ) this seems wrong,
But I also heard G53/2 did really apply til >5kWp so creating a vague grey area.
Also due to inverter/system loss , systems around 3.69-4 kWp wouldn't exceed 16A so G83/1-1 may still apply ?

Anybody fancy helping the class div  , not done anything above 3.68kWp, so far so if client want 3.69-4kWp whats the score ?
If we use a 3600 inverter ,then its no problem , what about a 3800 or 4000,  wackoteapot ,

cheers Jim
« Last Edit: July 19, 2011, 10:46:14 PM by jamesingram » Logged
jamesingram
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« Reply #23 on: July 19, 2011, 11:02:31 PM »

This seem to answer my question a bit ,
"The definitions in G83 are clear that the G83 system includes all associated
equipment (clearly that would include inverters and protection) and
that the output is at 230/400V and 50Hz. Therefore the output of your
system should be after the energy used by the associated equipment,
not simply the output of the energy source (e.g. the solar panels).
We recommend that you quote the NET generation figure which
is the actual generation capability of the scheme after energy
use for inverters etc has been taken into account."
http://www.ce-electricuk.com/som_download.cfm?t=media:documentmedia&i=728&p=file

Any one got a reliable figure for PV system loss ?
sma design tool give approx 82% for therotically Pv yeald to power fed into grid
or approx. inverter efficency of 95% depending on inverter used .         PVGIS suggest total system losses 14%

so inverter of max power 3.8kW ac ( 3.8 x 0.95) would work out 3.61kW into grid , so g83/1-1 applies
do this make sense ? cable loss also to consider .


definition of TIC,  Total Installed Capacity and DNC,  Declared Net Capacity here http://www.ownergy.co.uk/library/gosple/F2RCAP1d.pdf



« Last Edit: July 19, 2011, 11:33:16 PM by jamesingram » Logged
BruceB
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« Reply #24 on: July 19, 2011, 11:32:27 PM »

In that link, the reasoning/terminology in question and answer 11 is not quite right, but they do come to the right answer.  It is the output of the inverter that matters.  I have gone through it all in a post and discusion a month or 2 ago.

An inverter of maximum power output say 4kW can deliver 4kW assuming there are enough panels.  No efficiency calcs necessary.  If there are less panels than the inverter is capable of outputting then efficiency calculations are required to get the answer.

In a simple domestic PV set up then TIC and DNC are the same thing: the output of the inverter.  FIT band is decided by TIC.  DNO is generally interested in DNC.  DNC would be lower than TIC when there is some other plant drawing power from the generator, as an example external cooling systems.

The view offered by Ownergy in your link that TIC is the output of the panels  is wrong.

The 'grey area' between G83/1-1 Stage 1 and G59/2 is G83/1-1 Stage 2.  Have a look on the Energy Networks Association site to read about it.  I have done a few applications under that regime and it all works fine.  The one wrinkle now is that around me Western Power Distribution have started asking for the G83 parameters on inverters to be tweaked in that situation (over-frequency setting raised to 51.5Hz) or G59 standards applied, whereas a few months ago they were allowing standard G83 settings.

Regards
Bruce
« Last Edit: July 19, 2011, 11:38:43 PM by BruceB » Logged
jamesingram
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« Reply #25 on: July 19, 2011, 11:35:39 PM »

thanks again Bruce , got a link to your previous thread
cheers Jim
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BruceB
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« Reply #26 on: July 19, 2011, 11:46:23 PM »

Here you go.  Quite a long thread.  If the link works then my long explanation starts towards the bottom of this page.
http://www.navitron.org.uk/forum/index.php/topic,13403.msg151372.html#msg151372
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EccentricAnomaly
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« Reply #27 on: July 19, 2011, 11:51:26 PM »

I've heard 3.84kW mentioned ( 240Vac being used not 230Vac ) this seems wrong,

If the voltage actually is 240 V then that'd be OK as it's within (just on the edge of) the 16 A/phase limit. If it's 239 V then it'd be naughty at 16.0669... A.
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jamesingram
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« Reply #28 on: July 20, 2011, 04:14:53 PM »

thanks Bruce , I'll try to digest it all.
Quick look , it seems strange that there's not clear guidance from Ofgem ; with higher effiency panels coming on the market , getting as close to 4kWp and more importantly the 16A limit ffor easy installation on to the grid , is surely in the interest of the FITS funded national PV project
Getting as big and cost efficient system on each household as poss. to maximise returns for all. ( including us the energy bill payers funding this FITs scheme)
« Last Edit: July 20, 2011, 04:16:28 PM by jamesingram » Logged
Ted
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« Reply #29 on: July 20, 2011, 05:25:34 PM »

The ENA are discussing G83 changes. And the DTI PV install guide is going to be updated to version 3 with the intention of clarifying use of RCDs, frame earthing, TL inverters, etc.

But none of these things happen quickly.
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