DNOs and G83 limit

[solarfred]

Do you think DNO's could insist on only allowing inverters that are 16 amps limited by the manufacturer being installed into G83/1 installations? That solves the issue for UK Networks and I wonder if all DNO's might concur. That would not require a change in regulations as it is already a requirement that output is maxed at 16 amps. It does not resolve the disparity in voltage calculations though.

 

[Energetic]

Our DNO has, very sensibly, temporarily upped their limit to 17A per phase for G83 for 1 year. This means we can install a 4kw system on a 4000TL and still comply. This also means that national companies quoting here are telling customers they can't have an array above 3.6, which is nice...

 

[BruceB]

Which DNO?
And do you have a link?
Regards
Bruce

 

[solarfred]

Ted knows about these things Quote "G83 is quite definitely 16A at 230V for single phase. There is no guidance on how that is to be interpreted at different voltages.

Apparently discussion of G83 is on the agenda for the next meetings of the DCRP - a meeting of all DNOs under the auspices of the ENA. But I am informed that any decision on changes to G83 will take months to come into effect. The last update, from G83/1 to G83/1-1, took about 12 months." unquote.
So unless the DNO has changed the G83/1 regulation how can they do this?

 

[edexlab]

My understanding is that the DNOs have decided or been advised that they can allow upto 17kWp on a single phase under G83 if they want. I was chatting with our DNO Western Power about fitting 10kWp Wind and 10kWp of PV at my place and he told me about the 17kWp allowance on single phase, I don't want to have to pay to get 3 phase if I can avoid it. They tell me that they get so many conflicting memos about SSEG that it's a minefield for them to process. They are crying out for a policy that they can work to, I think the ENO&Ofgem need to pull their fingers out.

I think that this will depend a lot on your location and what the grid infrastructure is like, I've asked about the possibility of this figure of 17kw on a single phase and was told very unlikely in my area as the grid runs from 132kv straight to 11kv (its a fairly rural area) and Dno's have less opportunity to control voltage rises than with 132kv to 33kv to 11kv systems where apparently its less of a problem.

 

[wozzit99]

Posted on another forum

Hi

This is an email I received from Central Networks dated the 25th March.

Central networks comments are given in blue.

Hope this helps.



"So that I have definitely got this right could you confirm the following"



1. g83 goes up to 3.68kw after which g59 protection settings becomes the standard.

The standard G83 limit is 16A per phase (i.e. 3.68kW single phase or 11kW three-phase). For a single SSEG installation, this can be connected and then you can inform us later, providing all the commissioning documents etc to register for FIT. The standard G83 compliant inverter is acceptable (with upper frequency set to 50.5Hz). For connections >16A/phase, there has been a relaxation in the rules as given below.

2. It is possible to install up to 17kw on a single phase or 17kw per phase on a 3 phase system so long as the protection settings in the inverter are based around the g59 standard therefore negating the use of g59 relays ( this is depending on whether the line can take it )

We will accept a G83 1/1 type connection for a single SSEG installation, provided the inverters used are type-verified, and the capacity is no greater than 17kW single phase, or 50kW three-phase. You must submit an application form first (Appendix 2 of G83/1) to gain consent for connection, or to get costs for any reinforcement that maybe required. A G83 compliant inverter could be used, provided the upper frequency limit is set to 51.5Hz, or a G59/2 relay.

3. I have been quoting for a job where the customer requires approx 9.6kwp on a single phase supply. The intended design is to use 3 separate g83 inverters ,sma 3300 which as far as I am a where are configured with the g83 protection settings. Is it ok to use these inverters with the g83 settings as they individually are less than the 3.68kw limit ? The problem is I can't find a single inverter to use on a single phase which has the g59 protection settings and I don't want to get into the realm of g59 relays.

As above, the G83 protection should be set to 51..5Hz on the upper frequency

 

[wozzit99]

Looking at the protection settings on sma inverters they are set to the country relevent settings and they can not be altered.

How do you change the upper frequency to 51.5hz on a g83 type inverter?


Wozzit

 

[edexlab]

Looking at the protection settings on sma inverters they are set to the country relevent settings and they can not be altered.

How do you change the upper frequency to 51.5hz on a g83 type inverter?


Wozzit

I think it can be done using a communication device and with an authorisation code from SMA

 

[SolarCity]

Correct me if I'm wrong, but aren't the standards for G83 inverter a little more strict than a G59 relay needs to be?

 

[BruceB]

Yes, in terms of over-frequency, the G83 limit for GB is 50.5Hz and 0.5s, so I do not understand why Central Networks would say change the setting to 51.5Hz, as it is already within the G59 figure.

Regards
Bruce

 

[wozzit99]

Just a thought,

G83 over freq setting maybe in the range of G59 setting but it is also a full 1Hz below the reccomended limit. So nuisance tripping on larger systems might cause problems with the dno, thats why G59 settings are more forgiving. It does'nt explain why only the frequency limit has to be altered and not the rest of the parameters.

 

[BruceB]

I think you may be right there. Here is a G59 extract:



and also explains perhaps why sma went to the trouble of certifying their tripower range to the g59 standard in Feb this year

Regards
Bruce

 

[wozzit99]

Thanks Bruce

Is it only the tripower range of inverters which are accredited with g59?

 

[BruceB]

Do not know for sure, but just having checked their website for the 3000TL/4000TL/5000TL they only have G83/1 certification on the english page

 

[SolarCity]

Tripower inverters are accredited with G59? Are you sure?