Tic & dnc help urgently needed!!

[BruceB]

Like the 4000TL, SB3800 etc.

I've always considered the 16A limit to be a bit silly. If they had of made it 4kW instead they could have saved themselves a LOT of work.

Although to confuse things the 4000TL also has G59/2 certification so you can choose to operate it in that regime, or indeed as WPD often ask for an amalgam of the 2 regimes! Standards are wonderful things - but there can be so many of them.

 

[Earthstore]

Sorry Bruce, I have just spoken to DECC, TIC "total installed capacity" is just that.
The amount of panels installed IE 16 x 245 = 3920 (3.92KW)

DNC is declared Net capacity so if you restrict the output by using a G83 approved inverter then your DNC would be 3.68KW.

This is how confusing this industry is, when even the well versed professionals on here ( who I respect immensely), are confused.

 

[BruceB]

Well, with respect, whoever you spoke to in DECC is wrong.
They would be right if the inverter was larger than the kWp of panels installed, but not in this case.
I can only point you at the definitions in the legislation.
If you do not have a link I can find one.
I do not feel at all confused. Legislation often has some ambiguity, but not to my mind on this point.

Regards
Bruce

 

[SolarCity]

To be fair, I think it is the DECC that have it wrong.

 

[Earthstore]

Sorry chaps, I am just trying to help, but DECC are adamant that this is so.
I have also been led to various PDF files to explain this legislation , however I could not find the exact information (only amendments).
So, by what you are all saying you could install 5 KWP of panels, on a 3.68 inverter and the TIC and DNC would be 3.68 therefore making you eligible for the >4KW FIT rate?

 

[Gavin A]

eta - ah, actually this was in response to an earlier post, not the one above.

 

[BruceB]

I think you mean making you eligible for the less than or equal to 4kW rate, then correct.

Working through the definitions, for example here:
http://www.decc.gov.uk/assets/decc/...0100331172153_e_@@_fitlicencemodification.pdf
takes awhile, but can be instructive.

Regards
Bruce

 

[TedM]

This link should work:

http://www.decc.gov.uk/assets/decc/what we do/uk energy supply/energy mix/renewable energy/policy/fits/1_20100331172153_e_@@_fitlicencemodification.pdf

The definitions of TIC and DNC are on pages 3 and 9.

The other relevant one is "Eligible Installation" also on page 3.

Ask your contact at DECC to explain how an "installation" for TIC means panels only, and then "installation" means panels plus inverter when used for DNC.

You might also point out to them that, in a grid-tie system, panels without an inverter don't produce any watts at all - so the system would have a TIC of zero - by their definition.

 

[BruceB]

To return to AGSElectrical's original question. My recommendation is keep it simple, make TIC = DNC= 3.6 or 3.68 and give a consistent answer on the MCS certificate, G83 form, your schematic diagram and make sure your customer puts the same answer(s) on the FIT form. It is differences in the answers that will raise hares.

 

[Gavin A]

It is differences in the answers that will raise hares.

well I suppose it is March, and I'm feeling a wee bit mad...

 

[Earthstore]

Thanks chaps, I have read the links that you posted, and I have also read so many other files, just to try to understand this fully, why they have to have so many ammendments for what should be a simple rule is quite beyond me, still guess that is government for you.
TIC and DNC appears to be generic terms used for any type of SSEG, So DNC = power that can be produced- power that is used to produce that power.
I am still not convinced of TIC/DNC for PV, I do take on board your points though, and except that the Inverter makes up part of the system.
When I have time, just for my own peace of mind, I will research this further.
But thank you for all your comments.

 

[mdovey]

Given that DNC is defined to be the TIC less electrical consumed by the plant, so in effect the electrical losses, and since the inverter efficiency or capping is an electrical loss, the DECC view that the TIC is
the output of the panels doesn't seem unreasonable (in effect the output if all the wires have 0% loss and a 100% efficient uncapped inverter). This was certainly what I initial thought was the case before reading these forums.

However, although it has no official weight, I found this document the most convincing analysis - http://www.ownergy.co.uk/library/gosple/F2RCAP1d.pdf

This is almost the DECC view apart from in calculating the TIC of the panels it suggests using PVGIS data for the actual location and aspect of the panels rather than the STC value.

TIC definition
Based on the principles for defining the respective capacity measures in section 3 above, the TIC would be based on the output capability of the solar array given uninterrupted exposure to sunlight over a sustained period at its installed location. Suitable data on which this figure can be based is produced by the European Commission’s Joint Research Centre at Ispra, which maintains a resource called the Photovoltaic Geographical Information System (PVGIS)7.
PVGIS is based on extensive solar energy data throughout Europe. It has facilities to derive for any location and solar array angle three irradiance measures: Global ‘clear sky’ irradiance Global ‘real sky’ irradiance Diffuse ‘real sky’ irradiance
We propose to use the best month’s clear sky irradiance as the basis for the TIC calculation. This is the highest of the three figures, and that which best matches the ‘without interruption’ requirement of the definition.
We will use actual tilt angle and azimuth offset figures for installations constrained by the surface on which they are mounted (e.g. roofs). In the case of stand-alone and ground-mounted PV systems we will use the optimum tilt angle (also given by the PVGIS resource), and assume the array is oriented towards true South.
The TIC will then be calculated as the power output of the solar array at the average irradiance derived in this way.

DNC definition
The net output of a PV system, after conversion of light energy in each solar module, will be affected by configuration factors, such as ‘mismatch’ losses from the series and parallel interconnection of the modules, cable losses, voltage drops in metering and protection devices and the efficiency of the inverter and any other power conditioning equipment.
As described in section 4 above, it is proposed that these factors are deducted from the TIC to derive the DNC.