DNOs and G83 limit

[Ramjam]

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.

 

[edexlab]

I spoke to UK Power Networks today and they not only said it was the inverter output they're interested in but that they've changed to calculating their 16A over 240V (instead of 230) so we can install 3.84kW under G83.

240 v It makes you laugh ,I was talking to a bloke from SPManweb and he kept on about the calcs must be done with 230 v ,even though I told him yes I know, about 6 times, and yes i know why , I think the DNO's are just enjoying the disruption they cause I just wish we could do things the simple way in this country and all sing from the same sheet but ,then thats too easy!

so if I were you I would do it on 230v and you know you're in the clear because the next person you speak to from UKPN will tell you that 240 nominal value on calcs won't count and they will reject them

 

[DomB]

UK Power Networks actually ask for whichever is the lowest figure between (the inverter's AC output limit) & (the array's kWp x the inverter's efficiency).

So if the inverter was 97% efficient you could install a kWP system that was 3.84/.97 = 3.95 kWp - very nicely just below the 4kWp of the feed in tariff

Point taken tho Edexlab, I might try and get it in writing that UKPN now use 240V.

 

[SolarCity]

DomB: I think the FIT threshold is concerned with the kWp of the roof array, rather than what the inverter is capable of producing.

Also, your inverter sum isn't quite right. The kWp of the array should be multiplied by the inverter efficiency, not divided.

 

[DomB]

Ta BiggsSolar, Soz, I probably wasn't clear on my post there:

According to UK Power Networks you can install an array that produces 16A of AC after the inefficiencies of the inverter are taken into account. So the array can be bigger than the 3.84kWp (s'why I divided by the efficiency to see what array would give out 3.84 kW on the AC side after going through an inverter that was 97% efficient).

Just on your point about the FiTs - I see the MCS database asks for "Declared Net Capacity" - which I s'pose is what is declared to the DNO? For UK Power Networks, at least, that is the power on the AC side, not the array's kWp. The E.On FiT application also asks "What is the total installed capacity of your generator" - Is that not the same SSEG that the DNO is interested in, i.e the AC side? Maybe the FiT is not all about the kWp?

Man, I'm confusing myself now!

 

[SolarCity]

Man, I'm confusing myself now!

Ha ha! You're not the only one. There is so much conflicting information out there that it is difficult to know what's right and wrong.

 

[TedM]

I've tried to get OFGEM to issue clarification on TIC and DNC - to write it in words that a PV installer can make sense of - but they are not prepared to do it.

I am still going to try to find more senior people in OFGEM to get this done though.

Reality is that 99% of systems registered for FiTs have TIC and DNC as the same value. But TIC is the phrase used in the legal document that defines the tariff bands. OFGEM then go and use DNC in some other (non-legal) documents and the confusion multiples.

Why MCS only ask for DNC on the certificate is a complete mystery to me. Suppliers ask the owner for both TIC and DNC when they sign for a FiTs contract. The owner is probably the last person who understands the terms.

 

[DomB]

Trying to find some definitions of Total Installed Capacity & Declared Net Capacity. I'm guessing TIC is basically the kWp of the array and DNC is the AC side of the generator?

I notice in the Central FIT Register User Guide, which I understand the suppliers use to register FiT applications, TIC & DNC are both requested, so they are recognised as different.

I'll go ask MCS and UK Power Networks and come back here

 

[solarfred]

I've tried to get OFGEM to issue clarification on TIC and DNC - to write it in words that a PV installer can make sense of - but they are not prepared to do it.

I am still going to try to find more senior people in OFGEM to get this done though.

Reality is that 99% of systems registered for FiTs have TIC and DNC as the same value. But TIC is the phrase used in the legal document that defines the tariff bands. OFGEM then go and use DNC in some other (non-legal) documents and the confusion multiples.

Why MCS only ask for DNC on the certificate is a complete mystery to me. Suppliers ask the owner for both TIC and DNC when they sign for a FiTs contract. The owner is probably the last person who understands the terms.

I just checked the SSE FIT application form off their site as I was going to try and post a copy as I know it only mentions DNC. It does not say TIC at all. I was surprised to see it is a new form which says "Installed Capacity (kw)" now? So it is not even a defined calculation.

Happy days.

 

[Matt iecconnect]

Hi All
I am having the same problem.
No one will give me an answer as to size of array possible under G83.
Elec North west have sent me an email saying anything under 4kw is permitted under G83
As for Scottish power, who i deal with most , after 4 months of speaking to different people i still don't have an answer.
they have sent me a pre application form for any system over 3.68Kw which is headed for a G83 install.
I have 9 forms outstanding without response, The first submitted will be 7 weeks old this Thursday.
Called SP today and as always the person is on leave or off sick. Still no joy
Needs to be sorted ASAP.
How hard can it be to give an answer???????

 

[TedM]

The G83 limit applies to the inverter output. I'm still trying to get ENA to get the word on this out to all DNOs so that everyone has the same answer.

 

[Matt iecconnect]

Having spoke to a Scottish power engineer today, He confirmed that the max output of the array is measured by the max AC inverter output.
So it is possible to install a 3.92 kw system, comply with G83, as long as the inverter is rated less than 3.68kw.
If you require a G59 it will cost £900 + vat to witness test and carry out a network survey.
I have not yet received this in writing but expect to get it tomorrow.

Let the sun shine!!!!!!!!!!!!!!!1

 

[Jonjolavin]

This is a reply i received from UK Power Networks. This is the first one that has given an answer to so many questions:



Calculation of the size of the SSEG
Some installers appeared to mis-understand the rating of the SSEG as it should be reported on the G83 form. What is required is the maximum output from the SSEG, not the total rating of the solar panels. The calculation should be done, as follows:
• Add the total rating of all of the solar panels. Call this SP_Rating.
• Identify the efficiency of the inverter. Some inverters have charts showing how the efficiency varies with the DC Input Voltage, and other factors, and some just state an 'Average Efficiency'. Call this Inverter_Efficiency.
• Multiply the two figures (i.e. SP_Rating x Inverter_Efficiency). Call this Output_1.
• Compare Output_1 with the maximum rated output of the Inverter. Take the smaller figure. This is the SSEG output which should be reported.
Consider the following worked example:
7 solar panels rated at 235 Watts each, with a Sunny Boy 1200, (rated at 1200 Watts)
7 x 235 = 1645 Watts (SP_Rating)
Inverter Efficiency = 92% (Inverter_Efficiency).
SP_Rating x Inverter_Efficiency = Output_1.
1645 x 92% = 1513.4 Watts (Output_1)
Compare Output_1 (1513.4 Watts) with the rated output of the Sunny Boy 1200 (1200 Watts), and take the smaller figure, which is 1200 Watts.


Our guidance for installers is:

Here is our standard advice to new installers.
The first point to note is that G83 has a fixed upper limit of 16 Amps per phase at 240 Volts (3.84kW), which doesn't quite extend to the 4kW of the first band of the Feed-In Tariff. However, many installers, in talking to customers, who want to hear a big number, refer to the size of the installation according to the DC output of the Solar Panels, whereas we as a Distribution Network Operator, are concerned with the AC Output from the inverter. Please see the explanation below on how to calculate the output to record on the G83 form.
I've attached the G83 Commissioning Notification Form. This should be completed and sent no more than 30 days after completion of a G83 Installation. Although we don't insist that Installers use our form, we find it helps to ensure that the correct information is recorded.
You may find the following helpful in filling in the form
Information required by the form
See the following table. (Most items are self explanatory. Items which require more explanation are in bold.)

Line What is required
Customer supply number (MPAN) The MPAN is on every Customer's bill. Experienced installers collect this when they accept the order.
Property address (inc. post code) The address of the property where the SSEG is installed
Telephone number The Phone Number of the site where the installation is.
Distribution Network Operator (DNO) The name of the company who distribute electricity to the property
* See more information below.
SSEG owner The Customer's Name
Contact person The person who is to be contacted. For domestic installations, this will be the same as the SSEG Owner.
Contact telephone number The Customer's Phone Number.
Manufacturer and model type For PV and Wind Turbines, this relates to the Inverter
Serial number of SSEG For PV and Wind Turbines, this relates to the Inverter
Serial number / version numbers of software
(where appropriate) For PV and Wind Turbines, this relates to the Inverter
SSEG rating (Amps, Volts and power factor or kW - under normal running conditions) 1 This is the AC output from the Inverter.
* See below on how to calculate this
Number of Phases connected to the generation How many phases is the inverter connected to?
Maximum peak short circuit current (Amps at 240V AC) Some inverters indicate that they can deliver a greater output than their maximum rating for a very short period of time.
Type of prime mover and fuel source (For PV, state PV) For PV State "PV"; for Wind Turbines, state "Wind Turbine"
Location of SSEG within the installation 2 For PV and Wind Turbines, this relates to the Inverter
Location of multi pole isolator For PV and Wind Turbines, this relates to the Inverter
Installer The name of the company with the MCS Accreditation
Accreditation/Qualification Usually MCS
Address (including post code) The address of the company
Contact person The person in the company to talk to
Telephone Number The phone number of the person in the company to talk to
Fax Number The Fax number of the person in the company to talk to
E-mail address The email address of the person in the company to talk to
Final copy of circuit diagram Tick box to indicate that the information is provided
SSEG Test Report (Appendix 4) or web address if appropriate (not necessary if already provided e.g. under a Stage 2 connection) Tick box to indicate that the information is provided
Computer print out (where possible)
or other schedule of protection settings Tick box to indicate that the information is provided.
Electricity meter(s) make and model: On the existing meter

Calculation of the size of the SSEG
Some installers appeared to mis-understand the rating of the SSEG as it should be reported on the G83 form. What is required is the maximum output from the SSEG, not the total rating of the solar panels. The calculation should be done, as follows:
• Add the total rating of all of the solar panels. Call this SP_Rating.
• Identify the efficiency of the inverter. Some inverters have charts showing how the efficiency varies with the DC Input Voltage, and other factors, and some just state an 'Average Efficiency'. Call this Inverter_Efficiency.
• Multiply the two figures (i.e. SP_Rating x Inverter_Efficiency). Call this Output_1.
• Compare Output_1 with the maximum rated output of the Inverter. Take the smaller figure. This is the SSEG output which should be reported.
Consider the following worked example:
7 solar panels rated at 235 Watts each, with a Sunny Boy 1200, (rated at 1200 Watts)
7 x 235 = 1645 Watts (SP_Rating)
Inverter Efficiency = 92% (Inverter_Efficiency).
SP_Rating x Inverter_Efficiency = Output_1.
1645 x 92% = 1513.4 Watts (Output_1)
Compare Output_1 (1513.4 Watts) with the rated output of the Sunny Boy 1200 (1200 Watts), and take the smaller figure, which is 1200 Watts.

Generation up to 3.84kW Per Phase
You need to note that G83 allows for up to 16 Amps per phase at 240V AC (i.e. 3.84kW), and there is no flexibility to exceed 16 Amps per phase under G83.

Submitting G83 Notifications
The G83 form needs to be accompanied by a copy of the G83 Compliance certificate of the Inverter and a Schematic Diagram of the installation.
Our preferred method of receiving G83 registrations is by email to the address on the form. When G83 Registrations are made by email, it is sufficient to type your name as your signature.

MPANs
A key item of information for the registration is the MPAN, which is on the Customer's electricity bill. Experienced installers collect this information when the customer places the order.
There is a useful webpage to identify the DNO from the MPAN at:
Meter Point Administration Number - Wikipedia, the free encyclopedia

Generation between 3.84kW and 4.00kW Per Phase
If you are considering an installation which is between 3.84 and 4kW, then you will need to Apply for permission to connect this generation. Please complete our G83 Application form, making plain that this is for a single installation, and send it to the email address or the Fax number:
Email: [email protected] Fax: 08456 500248
The Application from is available at:
http://www.ukpowernetworks.co.uk/pr...83_multiple_installation_application_form.doc
The application needs to be accompanied by a Location Map.

Larger Generation
For larger generation, please contact me again for guidance on how to connect generation which is in excess of 4kW per phase.

 

[edexlab]

Nice to see something fom a Dno down on paper

although using 240v on calculations is the right way it should be done,as this is the voltage they are supplying, I'm curious why some use 240 and some 230
Dno's are using 230v ie Harmonised values and stating 3.68 kw before an aplication need to be made not 240v /3.84kw
It seems to me that those using 230v must be the right way to size the system (because of harmonisation etc)
the 3.84kw figure does'nt make much sense as 16 w extra to the 4 kw limit is'nt going to make that much difference until everyone has a system and by then they'll have rebuilt the grid anyway
anyone know why? as I'm sure they should all be using the same values in their calculations

 

[TedM]

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.

I'll be pulling together all the responses here and feeding them back to the ENA so that they can at least appreciate the issues involved for installers who are getting different advice from different DNOs and even different engineers within the same DNO.