FIT and panel replacement

Chris_Type_R

Hi all

I have a 2.02 kWh install from 2011 (9 x 225W Polycrystalline) which came with the house when we purchased in 2015. A neighbour has recently removed a large tree from their garden which was shading the install, so I have the opportunity now to make better use of this. Historically this has only generated 1207kWh per annum.

I've recently added Tigo Monitoring and Optimisers to the existing panels. 

Something I'm considering is replacing the 9 225W panels (2025W - polycrystalline) with 6 330W panels (1980-2010W - monocrystalline). The panels are on a ground floor part of the house, so this is something I could DIY - panel costs would be about £1k. They're pretty much plug and play in terms of dimensions. 

I hope to increase yield due to the new panels being monocrystalline and as there would be fewer, these could be arranged to be less affected by building shading in the morning. Also, they'd not have 11 years of degradation like the existing panels. 

Is this possible within the FIT agreement, and if so what would one have to do / how would one go about it ? I've previously spoken to someone at SSE who manages the FIT payments and they've stated that provided the capacity remains below 2.02 kWh there's nothing to be done formally - but I'm somewhat sceptical of this information ....

Thanks in advance for any help... 

QrizB

Any changes to a FIT-earning system need to be agreed with your FIT supplier, ideally beforehand.

DIY changes will not be MCS-certified and so will void your FIT.

Replacing the panels is likely to void your FIT.

Adding TIGO optimisers might be OK but you should check.

Martyn1981

Hiya, QrizB raises an interesting point about DIY changes, I hadn't thought of that, as the FiT provider may want to see a new MCS certificate.

You can add optimisers, and 'better' inverters etc, (as you've done) as that just improves the potential, but changing the size of the system will require notification to the FiT provider. If you went bigger, then they would pro-rata your FiT payments, so for example if you replaced all the 225's with 330's, then they'd pro-rata your payments to 2,025/2,970 ths.

Going smaller is interesting, I can see the point they are making, and it may be correct, but get it in writing, in fact when I was looking into 'stuff' like this, I carried out all the correspondence by e-mail, and found ways to keep asking the same questions in different ways to get multiple confirmations.

If you have Tigo optimisers (and they are suitable for 330Wp panels too(?)), then could you consider replacing all 9 panels whilst you're at it?

Chris_Type_R

Martyn1981 said:

Going smaller is interesting, I can see the point they are making, and it may be correct, but get it in writing, in fact when I was looking into 'stuff' like this, I carried out all the correspondence by e-mail, and found ways to keep asking the same questions in different ways to get multiple confirmations.

If you have Tigo optimisers (and they are suitable for 330Wp panels too(?)), then could you consider replacing all 9 panels whilst you're at it?

It's not so much going smaller as keeping roughly the same, but not more. Going any larger would require an inverter upgrade. Fewer panels would fit the Sun sweet-spot better. 

IIRC the Tigos are good up to 700W - and what I'm considering *is* changing all 9 panels - essentially going from 9 to 6 physical panels. Going to monocrystalline should in theory increase yield on cloudy days - which we seem to have a lot of.

The 330W panels themselves have downloadable MCS certificates - but obviously this would not be what's registered against my install. 
 
I've not collected enough data yet, but I suspect at least one of the existing panels is performing below expectation (after factoring in age losses). Replacing panels - where manufacturers are unable to supply replacements / can't honour warranties isn't something that there's much information about. 

(thanks for the PV FAQ btw)

Chris_Type_R

Five of these could in theory replace the 9 x 225s - https://midsummerwholesale.co.uk/buy/perlight-monocrystalline-solar-panels/perlight-400w-delta

Exiled_Tyke

As I've posted before, I asked my installer about pro-rata FIT payments for amended installations.  Their view was that they hadn't heard of any FIT provider agreeing to it and they wouldn't recommend even trying as once the system has been changed, if the FIT provider changes their mind on allowing it, then it will be too late and everything will be lost.  When I added two panels to my system it was kept entirely separate from the existing system. We used one 600w microinverter and a separate meter to measure production. So I don't get paid for any export from these and I can't monitor them online either but I can live with that .

All in all I wouldn't risk changing the panels out. 

Exiled_Tyke

I think I would also be inclined to inform the FIT provider about the reduced shading, otherwise they may be suspicious of your increased production and withhold payments until they can check the meter.    

Chris_Type_R

Exiled_Tyke said:

I think I would also be inclined to inform the FIT provider about the reduced shading, otherwise they may be suspicious of your increased production and withhold payments until they can check the meter.    

I did ask in the past and only had the response that it wouldn't matter provided the rating is not exceeded. 

Strategically I'm taking meter photos every month as supporting evidence if it should be required.

gefnew

This may help on the fit question.
How to avoid jeopardising FiT payments with solar repairs - Farmers Weekly (fwi.co.uk)

Chris_Type_R

gefnew said:

This may help on the fit question.
How to avoid jeopardising FiT payments with solar repairs - Farmers Weekly (fwi.co.uk)

Thanks, I had found that previously - and might have prompted me thinking about the scenario of replacement with better panels by reducing overall panel count. 

I think it's more guidance than fact though. 

QrizB

Have you seen this document?

https://www.ofgem.gov.uk/publications/feed-tariffs-guidance-renewable-installations-version-16

Chapter 6 concerns modifications. In particular paras 6.14 to 6.17 seem to cover your situation.