10kw vs 10.08kw

[BruceB]

Here is my thinking. First some definitions:

Total Installed Capacity - means the maximum capacity at which an Eligible
Installation could be operated for a sustained period
without causing damage to it (assuming the Eligible Low-carbon
Energy Source was available to it without
interruption), a declaration of which is submitted as part
of the processes of ROO-FIT Accreditation and MCS certified
Registration;

Declared Net Capacity - means the maximum capacity at which the installation can
be operated for a sustained period without causing damage
to it (assuming the source of power used by it to generate
electricity was available to it without interruption) less the
amount of electricity that is consumed by the plant;

Eligible installation - means, on a Site, any Plant Owned by a FIT Generator
capable of producing Small-scale Low-carbon Generation
from the same type of Eligible Low-carbon Energy
Source, the Total Installed Capacity of which does not
exceed the Specified Maximum Capacity;

Small-scale Low-carbon Generation - means the use, for the generation of electricity, of any
Plant:
(a) which, in generating electricity, relies wholly or
mainly on an Eligible Low-carbon Energy
Source; and
(b) the Total Installed Capacity of which does not
exceed the Specified Maximum Capacity;

Eligible Low-carbon Energy Source - means the following sources of energy or technology:
.............. (d) solar photovoltaic;

Plant - means any equipment, apparatus or appliance;

In abbreviated form the argument is as follows. TIC is the maximum an Eligible Installation can be operated at. An Eligible Installation means any Plant. The Plant is the inverter. The definition of Small-scale Low-carbon generation refers to the Plant as having the TIC. The solar panels are the Eligible Low-carbon energy source. It is the maximum output of the inverter, coupled to the panels, that is relevant in declaring TIC.

As I read it the DNC definition is all about ac being fed into the grid. The TIC uses identical wording and I believe it is also referring to ac power output. There may be other equipment in the plant room that draws power which reduces the TIC figure to a DNC figure. In the case of a simple low voltage inverter situation without any other equipment on the ac side then I believe the best interpretation is that DNC = TIC, less perhaps 1% for cable losses. I do not believe potential power in from the solar panels on its own is relevant to determining the TIC if it is the inverter limiting the maximum power out rather than the number/size of panels connected.

Regards
Bruce

 

[TedM]

And it is worth pointing out that the terms 'TIC' and 'DNC' have been in use for much longer than the FiT. They were definitions already in use that have simply been re-used by OFGEM.

 

[SolarCity]

Fair enough. It's fair to say that it's time I changed my opinion. Thanks for the info, fellas.

 

[EWebster]

Wow, started a good discussion :yes:

Thanks for everyone's input. It's all been very helpful.

Euan

 

[whlphil]

This something Ive been trying to get an answer on for a while, whilst I dont think the answer below is correct this is what OFGEM said today

TIC is the name plate rating for the PV panels. TIC is the size of the plant that determines the FiT tariff level (eg 10.08 is above 10 and thus in the 10 to 50 banding)

DNC is the inverter AC output and determines the classification for MCS or ROOFiT eligibility

eg a 55Kw PV system (rated at 55Kw STC) with 3 x 15Kw inverters giving a 45Kw DNC would be classed for FiT's in the 50-150Kw band but fall under MCS as DNC is below 50Kw.

Honest to god this makes my head spin, surely this is something thats being commented on by someone who doesnt know what they are on about as usual.

 

[BruceB]

Are they willing to put that in writing? I believe I recall Ted tried to get something definitive out of them but they were not willing.

 

[whlphil]

Are they willing to put that in writing? I believe I recall Ted tried to get something definitive out of them but they were not willing.

They have put it in writing but TBH the email is a tad crappily written as usual refers back to the guidance but does more or less confirm this as their version, that said I have had this before with the site extension loophole where one said the loop hole wasnt there but when I pushed and got the right person they confirmed (and put in writing) that the loophole did indeed exist (hope it doesnt get closed too quick im due 1Mw order tomorrow). So as usual its all a case of who you talk to!

Ive put an email into some friends on high to clarify and hopefully they will pull the chain of the right person, I'll let you know if I get an answer.

 

[solarfred]

What does the FIT application form say? The DNO is not interested in FIT only in protecting their network so the inverter output is paramount in their view. The FIT form for SSE has changed it's wording from "TIC" to "Installed Capacity". Why would they do that? In my view that term is not defined so you can enter whatever you feel is correct and that means the DNC after all losses. For a G83/1 that should be up to 16 amps/240volts (then the DNO is happy).
If you ask the MCS people they will say the FIT is determined by the nameplate output of the panels - or they did when I asked them but sadly they do not understand their own system and will not provide a written reply to this issue but hide behind the definitions which - as above are not always defined. Needs them to bring a case for an "oversized" array so it can be finally resolved.

 

[whlphil]

What does the FIT application form say? The DNO is not interested in FIT only in protecting their network so the inverter output is paramount in their view. The FIT form for SSE has changed it's wording from "TIC" to "Installed Capacity". Why would they do that? In my view that term is not defined so you can enter whatever you feel is correct and that means the DNC after all losses. For a G83/1 that should be up to 16 amps/240volts (then the DNO is happy).
If you ask the MCS people they will say the FIT is determined by the nameplate output of the panels - or they did when I asked them but sadly they do not understand their own system and will not provide a written reply to this issue but hide behind the definitions which - as above are not always defined. Needs them to bring a case for an "oversized" array so it can be finally resolved.

The suppliers don't get to decide how to apply definitions that's OFGEM's job, in my experience there's very few in the Renewables team at SSE that know what they are on about, not going on what OFGEM say is a risky game, just make sure that If you are going to take their (SSE) corner that you have it qualified in your quote to indemnify you.

 

[PJC]

DNC is what mcs, the DNO and energy providers are interested in . The fit payments are set by DNC, I have had confirmation of this from MCS and Eon. IN most cases the DNC is the capacity limit of the inverter.

 

[BruceB]

With respect, you are making the mistake of believing that MCS, Eon, Ofgem and other DNOs and suppliers when you get them on the phone know what they are talking about. Whilst DNC is what the DNOs 'should' be interested in from the perspective of effect on the network, it is quite unequivocal in the legislation as it currently stands that the FIT rate is determined by the TIC not DNC. If anyone is giving any advice contrary to that then they are wrong. Now what TIC is might be up for debate (personally I do not think so) but that is another matter.
Regards
Bruce

 

[TedM]

The FiTs bands are based on TIC. The 50kW MCS limit is based on DNC.

It would solve a lot of problems if the FiTs bands were based on DNC which, in my opinion, they should have been in the first place. In fact, for small systems, there is no point in having any distinction between TIC and DNC. There should only be Installed Capacity and that defined as the output from the inverter. Basing capacity on DC when the system pays for AC generation is plainly ridiculous.

That FiTS bands are based on TIC is clearly shown in the tariff tables in the Standard Conditions: http://www.decc.gov.uk/assets/decc/...0100331172153_e_@@_fitlicencemodification.pdf

See Annex 2 from p22 onwards.

If you get any nonsense from MCS (Gemserv) or anyone else on this then please point out the error of their advice.

 

[Worcester]

@TedM, you probably remeber this from the email you got from the ENA:

Q3 Can we get clarity as to exactly what the 16A per phase limit for G83 actually relates to? Is it based on:
a) the Declared Net Capacity or the Total Installed Capacity of the system (as given on the MCS commissioning certificate) ?
b) the manufacturers quoted peak output of the PV panels (or other applicable prime mover 'nameplate' figure) ?
c) the maximum grid-tie inverter output?
d) if it is based on the inverter output then is it based on the manufacturer's maximum rating for the model of inverter or based on the (sometimes programmable) actual maximum inverter output figure
e) figures used at a - d above are usually given in Watts - so, in order to convert to Amps, is 230V or 240V to be assumed? I believe the definition in G83 specifically states "230V ac" but many DNOs seem unaware of this minor fact.
f) can you confirm the maximum Watts applicable to a 3-phase supply?

(a) For Inverter systems it is the output of the inverter so it would be possible to install a 3.6kW inverter with 4kW peak of PV panels under G83
(b) No see answer above
(c) Yes see answer above
(d) maximum continues rating
(e) 230 volts is the nominal voltage for the whole of Europe
(f) 230x3x16= 11,040 for practicable purposes this is 11kW, split evenly over three phases. The following is not allowed
phase 1 4kW
phase 2 4kW
phase 3 3kW
as two phases exceed 16A per phase

Unbalance is allowable up to to the following limit
phase 1 3.7kW
phase 2 3.7kW
phase 3 any value under 3.7kW

The answer to (a) is the crucial one, TIC and DNC are based on inverter output .

The panel ratings are irrelevant, how about I sell my 260W panels rebadged as 250W panels because I have a surplus of them and everyone wants 16 x 250W not 15 x 260W, as a manufacturer with a warehouse full of 260W panels what would I do?