4 KW or Under

[liquidity]

p.s. liquidity, y'asked earlier for that list of inverters SSE allow :

View attachment 7293

It's a pdf, hope that works..

Cheers

It does indeed; thanks. I guess the SB 4000TL isn't listed as it will only be G83 compliant if the output is capped by the installer at 3680 watts?

 

[DomB]

Cheers liquidity, I've also attached SSE's 'PV installers newsletter' which might be of interest there. It seems to be the "maximum rated output of the inverter in Watts" which is defining their compliant inverter list.

View attachment PV installers newsletter Mar 2011.pdf

It's interesting that that newsletter says, regards output calculations "There is the possibility of diversity with multiple installations, due to them being on roofs facing in different directions. If anyone has any ideas about how this should be calculated please let me know and if we can agree on a formula then I’ll arrange for it to be distributed to all known installers in our area."

 

[Worcester]

In the example I used above with the East West split, I actually used an Inverter that has a mximum rated output of 3.68kWp (the G83 limit), so I didn't need to go the whole of Bruce's way and do the math, I let PV*Sol tell me that a PVI 3.6 was OK, and I happen to know that it's TIC figure is 3.68kWp, because it's maximum continuous rated output is 16A.

When you fill inthe G83 form (I know we are mixing DNO notification and FiT's here, just bear with me) .. they don't care what panels are used, the SSEG is the inverter, becasue that is what creates the power, there is an argument that says you could change your panels without nescessarily telling your DNO (so long as it doesn't go over 3.68kWp), however if you change your inverter you MUST notify them.

So I would conmforatbly declare that installation as 3.68kW on the FiT form.

If the Inverter was say an SMA SB4000TL which isn't limited to 16A, then I'd have to do the extra math that BruceB mentions to ensure that it comes in the 4kWp FiT's band.

 

[SolarCity]

Fascinating thread. Although I have to admit that I'm not convinced. There seems to be far too much conflicting information out there and for that reason I'm just a little windy about installing >4kWp and still expecting to fall within the 4kWp band - although I agree that the definitions seem to support this as acceptable.

 

[PvNewbie]

The definitions don't include angle of incidence on roof which worries me. They only define number of panels x kWp x inverter efficiency. So I can't see how you can argue the case.

2.3kWp on East and 2.3kWp on West = 4.6kWp. Yes, it will never max at that but to me, the definition says it is 4.6kWp system. (not allowing losses for inverter efficiency)

So although I agree with all that has been said, rules-is-rules. How can triginometry overcome it?

 

[BruceB]

The statutory definitons of TIC and DNC make no reference to kWp. What definitions are you thinking of?

 

[PvNewbie]

Sorry BruceB, my mistake

What I meant to say was number of panels x their stated output x the inverter efficiency for the TIC. Where does angle of incidence come into that?

 

[BruceB]

Because the formula you are quoting is a simplification and gives the maximum output from a single array when the sun is shining directly at it (or more accurately at a defined irradiance level. If you have arrays pointing in different directions then clearly you cannot just add the figures from the 2 arrays together because the sun cannot be shining from 2 directions at once. If you want to know what the combined output is when the sun is in any particular direction then trigonometry is required.
Regards
Bruce

 

[PvNewbie]

Thanks Bruce I understand that. Please tell me if I'm being stupid here but what I'm trying to say is that the argument appears to be that you can use trigonometry to justify going over the 4kWp limit. My query is that how can you when the legal definition for TIC is number of panels x their stated output x the inverter efficiency. Not number of panels x their stated output x the inverter efficiency x factor allowing for angle of incidence of panels.


​I may be missing the point totally here. I'm just trying to clarify it in my head. Your help/clarification appreciated.

 

[BruceB]

The legal definition is NOT what you are saying, it is:

“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 Lowcarbon
Energy Source was available to it without
interruption), a declaration of which is submitted as part
of the processes of ROO-FIT Accreditation and MCScertified
Registration;

Regards
Bruce

 

[solarfred]

".......maximum capacity at which an Eligible
Installation could be operated for a sustained period
without causing damage to it (assuming the Eligible Lowcarbon
Energy Source was available to it without
interruption),......"

As I have said that seems to me to mean the maximum capability of the kit. It says "could" not "is". If it happens to be on different aspects then tough - you could install it really badly and bring that into the calculation if you took this to the n'th degree. The maxiumum capacity is the panels * inverter efficiency. It states " assuming the eligible low carbon energy source is available to it without interruption" A legal definition is open to interpretation until a precedent is set. I think we are playing a dangerous game here.

 

[PvNewbie]

So, is 'the maximum capacity at which an Eligible Installation could be operated for a sustained period without causing damage to it' partially dependent on angle of incidence in the case of PV?

 

[BruceB]

yes, if that is limitiing the maximum output rather than simply the size of the inverter

 

[PvNewbie]

Ahaaaa! Got it.

So I suppose the next question is how do you correlate angle of incidence to output of panels?

 

[pirhead]

Pardon my ignorance all this talk of TIC is above me as a newbie can u break it down evenr further:shocked3: