Tic & dnc help urgently needed!!

[AGSELECTRICAL]

Hi Forum

We have just completed our first installation and I need help with registering this please.

It is a 4 kw system, this consists of 16 x 245kw panels, south facing, no shading and 30 degree angle.

I am being asked for Total installed capacity and declared net capacity.

Can someone advise me on how to calculate this asap please.

Please email me on [email protected]

Thanks in advance

Amanda

 

[TedM]

16 x 245W (not kw!) = 3920W or 3.92 kW

From this you can deduct for the efficiency of the inverter (maybe 95% or so but you should look it up from the manufacturer's figures)

3.92 * 95% = 3.724 kW

If the inverter max capacity is less than that then use that figure instead.

As both will be below the magic 4 kW threshold you get the highest tariff.

Use the same figure for both TIC and DNC.

(Umm, you should have known what this figure was before you started as you need to pre-notify your DNO under the G83 regs if it was going to be more than 3.68 kW)

 

[moggy1968]

unless you used a 3.6 inverter!

 

[AGSELECTRICAL]

We have used a 3.6 inverter, would this change the calcs or the TIC and DNC??

 

[TedM]

As I said, if the inverter max capacity is less than the panel figure then use the inverter figure instead.

Don't forget to notify the DNO.

 

[Gavin A]

either 3.92kW if the inverter isn't limited, or 3.68kW if the inverter is limited to 16amps / 3.68kW.

 

[AGSELECTRICAL]

Hi Ted

So just to clarify its 3.6 * 95%= 3.42

So TIC & DNC is 3.42 correct?

 

[Gavin A]

Hi Ted

So just to clarify its 3.6 * 95%= 3.42

So TIC & DNC is 3.42 correct?

no. The inverter output limit already factors in any inverter losses.

 

[AGSELECTRICAL]

Im confused then.........

 

[AGSELECTRICAL]

so is it just 3.6 then for both TIC & DNC??

 

[GaryM]

so is it just 3.6 then for both TIC & DNC??

Yes, if that's the output of your inverter.
Out of interest, what inverter are you using?

 

[Earthstore]

NO.
TIC total installed capacity, 16 x 245 = 3920 which is 3.92 KW.

DNC declared net capacity, that should be the maximum output from the inverter, which as you have not asked for DNO approval should be done under G83 which means the inverter that you have used should be G83 compliant and have a certificate stating maximum output of 3.68KW (or less)

If you have not used a G83 inverter, you may be in the poo.

I hope this helps.

 

[Earthstore]

Sorry Gary, I think you are wrong on this one, I hope my explanation clears things up, Between us all though we do have a vast amount of knowledge.

 

[GaryM]

To be honest, I was just going what the majority seem to state, Ted included. Your explanation however makes sense.

Although, the MCS certificate stated 4kW for my DNC (4kW of panels and 3.68kW inverter) so I also enter 4kW for TIC on my FiT application.

 

[Earthstore]

I believe the confusion comes if you are close to a FIT change IE 4KW, or for an export meter (30KW).
The DNO is totally separate to the FIT, all the DNO want to know is DNC, the maximum amount of electricity that could be poked into their system.

What the FIT needs to know is TIC, as if it is over say 4KWP then you should be on the 4-10KWP tariff and not the higher>4KW

So if you install 4KWP of panels and use a G83 approved inverter (max 16amp max output 3.68kw) install and then inform the DNO within 28 days, you are covered for both parties.
However if you install 4KWP of panels and use an inverter that is not G83 approved then it is under G59 which you have to get prior approval from the DNO first, but would still get the higher >4KW tariff rate.

I do hope this makes sense?

 

[SolarCity]

As far as I'm aware, the inverter specifications for G83 don't mention power output at all.

If the inverter is limited at 3.68kW then TIC and DNC are both 3.68kW.

 

[BruceB]

Oh dear this is getting confused. Ted, Gavin and Gary have it right and Earthstore you are incorrect saying in this case the TIC is the kWp of panels installed. If the inverter is 3.6kW output and the array's output is greater than that then the TIC and DNC are just the inverter output, ie 3.6kW.
Regards
Bruce

 

[BruceB]

And SolarCity understands!

ER G83/1 does mention 16A per phase often, but the tests for g83/1 compliance do not include a maximum current test. So with DNO agreement, an inverter can be operating under a g83/1 regime in terms of voltage and frequency cut-offs, but be operating at a current and power level beyond which G83/1 is normally applied, but where G59/2 is.

 

[SolarCity]

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.

 

[TedM]

TIC and DNC both refer to the maximum capacity of an 'eligible installation'. Panels on their own are not an 'installation'.