Can 7.8kw of panels be fitted onto a G83 3680w 16 A system?

[finewine]

Right guys, perhaps a rather odd question but I am considering adding another 3.92kw of panels onto my North West roof. I already have a 3.92kw system on my SE facing roof which was installed on 26th March and is performing very well indeed with approx 12% generation above SAP predictions (Considering the dull spring I am very happy)
I am not suggesting a whole new system, just adding it as another string to my existing SMA 3600tl . This system is already limited to 3680w and 16A and therefore this would not be exceeded. This way I wouldn't be breaking G83 rules and also wouldn't end up with less than 21p/kwh

The reason I would like to do this is SAP calculations for my Northwest roof (40 degrees) suggest an annual generation of 2350kwh. I think in reality in sunny weather during summer this will be clipped back but my thoughts are this roof will be generating in the morning (during the sunny weather last week the roof was sunny from 5am until 8.30 am and then again from 11.30am as the sun was overhead. From 4.30pm the sun is already at a good angle to the roof until sunset. The SE facing roof made around 28.5kw/h a day last week and I am sure having watched the back roof I could have squeezed at least another 15kw from the back roof as the sun shone on it for around 12 hours.

My installer said it would cost around 4-5k to add the extra panels on the back roof but is unsure how this will effect my existing FITS etc.

I have made a few phone calls, the DNO says as long as its limited I can have an unlimited amount of panels but I really an not sure as I haven't heard of anyone else doing it. The SMA 3600tl will on some days be running at full capacity for most the day but apparently it is capable of this. I have read other threads on here where several installers have spoken about 5kw of panels on a G83 installation.

This is just an idea at the moment and may well be a complete non starter. ANy thoughts would be greatly appreciated.

My total outlay will be around 12 - 13k for this system if I went ahead with an annual generation hopefully around 4900 - 5200kwh giving an annual fit return of between £1102.50 and £1170 before savings on electricity.

 

[Gavin A]

This is a 6kWp east west system we installed a while back on a 3600TL, with 2.5kWp on a steep ESE roof, and 3.5kWp on a shallow WNW roof.

As you can see, it pretty much self limits around the 3.6kWp mark (the figures are for half hourly readings, so double them to get the actual reading)

I'd caution that unless your roofs are relatively steep, I think in peak summer you will be pushing the inverter pretty hard, and the limiting will be reasonably significant (but probably less than 1% of output still), but you're on the right tracks.

I assume you know that this extra array will only be paid at the 4-10kWp rate?

 

[Earthstore]

Gavin, are you sure that the second arrry will be on the 4-10 KW Fit, only I have had this conversation before and it is all about TIC, and as the inverter makes up part of the system, then the TIC could be classed as 3.68KWP, or you could use DNC, I know it is a very grey area, and you should assume that it will be the lower tarrif, it all depends on who you ask really.
What does TedM the now famous think?

 

[Gavin A]

Gavin, are you sure that the second arrry will be on the 4-10 KW Fit, only I have had this conversation before and it is all about TIC, and as the inverter makes up part of the system, then the TIC could be classed as 3.68KWP, or you could use DNC, I know it is a very grey area, and you should assume that it will be the lower tarrif, it all depends on who you ask really.
What does TedM the now famous think?

I'm absolutely certain in this case because it's adding a second system.

I also know for sure that Ofgem currently regard TIC as being the rated output of the panels alone, although we still dispute this, and Ofgem have offered no support for their position legally, merely reasserted their position / tried to pass the buck to anyone else, squirmed, reasserted the position, and basically dared us to spend thousands taking legal action against them. I've had firm legal advice that their position is unlawful, but they don't care about stuff like complying with the law apparently.

 

[Earthstore]

I too have been up the same road with OFGEM, DECC, as well as reading through all the rules myself, they could not make things more complex and unclear if they tried, but I guess we should be getting used to it.

 

[finewine]

Hi Guys, Thanks for your replies. Gavin A, with regards to the FIT, this is the area that I am really confused about. The DNO said that the rated output of the panels wasn't an issue as in their eyes a 4.00kw system could actually be producing as much as 4.25kw\h at absolute peak generation. The chap was helpful and said lots of people are installing 5 or 6kw in order to get maximum generation in duller weather but that the system would need to be limited to 3.68kw. However he was unsure how adding extra panels would affect my system and suggested I seek expert help. The Ofgem customer service agreed that the DNO were correct and so I asked for confirmation on this in writing. They said it was not possible to put this into writing and suggested I would need to seek professional advice on how it may affect my FITS ETC. Apparently it is the customers responsibility to interpret the legislation and it is not appropriate for Ofgem to give their opinion in writing on this. I then contacted my installer again and they said they are getting the same answers. Surely if the those that regulate the industry cannot give a firm answer then who can?

Basically, if I can get 21p/kwh then I am going to go ahead. Another question is will my house need an EPC. Both Ofgem and DNO said this was a 'variation' on an existing system and therefore wouldn't need one but my installer has never heard of any such term.

 

[Gavin A]

yes, Ofgem's position on this issue is an absolute disgrace. A complete failure to fulfill their remit as the scheme and industry regulator, and IMO the people involved should be forced to resign in disgrace... ain't gonna happen though, as it's an establishment stitch up despite them knowing the legislation doesn't say what they want it to say.

 

[Earthstore]

I do wonder if it is about time that they recieved a legal letter asking for clarification on this, not just to be pointed to yet another file being told "the information you need is all in there" when it clearly is not.

I had recent emails to and fro, trying to clarify an EPC point, even though you ask a direct question and point out that the answer is not in the 88 page document , they still insist it is.


Still, I may have the misfortune of meeting Barking this month, could be interesting...