In-roof or on-roof panels - recommendation for suppliers / intallers South West

[Walshie]

Hi all,

Apols for the idiot question but....

I'm about to do a renovation which will involve the while roof being recovered in slate.

Seems like a good opportunity to go for in-roof panels - for no other reason than they look better.

However, be good to get some views on pro's / con's before a take a leap into the unknown!

 

Also, would be great to have some recommendations for suppliers / installers in the South West - I'm in Porlock.

 

Thanks for your help,

 

W

 

 

[brumeye]

Watching as we're thinking of doing something similar. I'm on the fence given in-roof is supposed to be a bit less efficient due to less heat dissipation (10-15% less output?) and thinking about the long term, I also wonder whether replacement will be more difficult when needed.

Edited December 28, 2024 by brumeye

[Alan Ambrose]

Pros:

 

+ Fewer tiles, so less cost and weight.

+ Better looking (maybe).

+ Easier to protect against nesting birds.

 

Cons:

 

+ More complex fitting (check out the instructions for choosing trays and for battening).

+ Harder waterproofing detail.

+ Lock in to a range of panel sizes when renewing in 20-30 years / possibility trays have degraded by weather or UV and need replacing,

[G and J]

  On 29/12/2024 at 10:19, Alan Ambrose said:

Pros:

 

+ Fewer tiles, so less cost and weight.

+ Better looking (maybe).

+ Easier to protect against nesting birds.

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Tick to all those….  In fact the reduced natural slate costs make Solar pv really easy to cost in, and I think it’s looks a lot better.

 

  On 29/12/2024 at 10:19, Alan Ambrose said:

Cons:

 

+ More complex fitting (check out the instructions for choosing trays and for battening).

+ Harder waterproofing detail.

+ Lock in to a range of panel sizes when renewing in 20-30 years / possibility trays have degraded by weather or UV and need replacing,

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Not sure about complexity of fitting.   Having been on a roof recently looking at GSE trays they look pretty simple to me, and an awful lot less faff than retro fitting bird guards.  The flashing detail looked easily doable too, so I’m not sure about that as a downside either, especially given the real waterproofing of a roof is the underlay, which is unaffected.

 

I’m sitting in a house that we built 33 years ago, with a design life of 25 years.  Plus, in 30 years a few dicky solar panels will be the least of my worries as I stumble through my tenth decade, so that one won’t worry me personally, and I’m not sure, with optimisers fitted, if it’ll be much of a worry to most peeps.  
 

I did at one point concern myself with the loss of efficiency at high temperatures, but that could be reduced by counterbattening and besides, that efficiency drop will only be when there’s tons of solar anyway, so for me less of a concern.

 

Regardless of the technicals, I think flush solar looks finished, so that’s the decider for me.

 

 

[SteamyTea]

  On 28/12/2024 at 22:20, brumeye said:

I'm on the fence given in-roof is supposed to be a bit less efficient due to less heat dissipation (10-15% less output?)

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This is a bit of a red herring.

It will only get a reduced output when it goes about 25°C, and the radiation is above 1000W/m².

So a few days a year, at a time when PV is producing the most.

Most PV modules will have a greater output than the nameplate rating anyway, that way, as they age, they stay withing the guaranteed output.

It is never worth chasing the last few percent of efficiency at the extremes.

[Gone West]

The only potential problem I have with an in-roof system, is, if a PV panel needs replacing in the future, will the same size PV panels still exist.

[torre]

No idea of suppliers in the SW but we'll be using Viridian in roof panels. UK based and been around a long time, they supply a number of UK housebuilders and are now owned by Marley so hopefully a good chance of replacement availability in future and good flashing compatibility with common UK roof finishes.

[G and J]

  On 30/12/2024 at 09:11, torre said:

No idea of suppliers in the SW but we'll be using Viridian in roof panels. UK based and been around a long time, they supply a number of UK housebuilders and are now owned by Marley so hopefully a good chance of replacement availability in future and good flashing compatibility with common UK roof finishes.

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Maybe I should put half a dozen of the same panels on my man cave at the bottom of the garden to use on the main roof if needed.  

[Walshie]

Thanks all for the info.

The Viridian kit looks good!

[Nickfromwales]

  On 29/12/2024 at 11:40, G and J said:

Not sure about complexity of fitting.   Having been on a roof recently looking at GSE trays they look pretty simple to me, and an awful lot less faff than retro fitting bird guards.  The flashing detail looked easily doable too, so I’m not sure about that as a downside either, especially given the real waterproofing of a roof is the underlay, which is unaffected.

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+1. 
 

Been on a few in-roof installs and I was surprised at just how quickly it all went in, vs a re-roof job I did ages ago where we had to take an on-roof system off and then reattach it afterwards. What a PITA that was. Pigeons nested behind most of the peripheral panels to a bit of ethical uncomfortableness too factor in, so the further ugly / also PITA of fitting vermin skirting is another thing I’d want to avoid at all costs.

 

In-roof, every damn day of the week. 
 

Choose a very good quality panel, with a warranty tied to the manufacturer vs one that you’d need the installer for. Lots of people lost their cover when the FIT ended and around 5000 MCS registered companies disappeared…..

[G and J]

  On 09/02/2025 at 15:43, Nickfromwales said:

with a warranty tied to the manufacturer vs one that you’d need the installer for.

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Good point. 
 

Presumably that would cover panel only, as opposed to any peripherals like optimisers. 

[Dillsue]

  On 09/02/2025 at 15:43, Nickfromwales said:

 with a warranty tied to the manufacturer vs one that you’d need the installer for. Lots of people lost their cover when the FIT ended and around 5000 MCS registered companies disappeared…..

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We've had a couple of optimisers fail and I've gone direct to SolarEdge for replacements and I think the panel warranty from JA SOLAR would be the same. I don't recall seeing anything in the warranty wording that needed the installer to make a claim.

[Nick Laslett]

  On 30/12/2024 at 07:50, Gone West said:

The only potential problem I have with an in-roof system, is, if a PV panel needs replacing in the future, will the same size PV panels still exist.

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This is an interesting point. The GSE tray system has flexible adjustment for height, but the width is fixed. 
 

I actually had to deal with this issue because I bought 2 panels at the beginning of the build to use for on-site power whilst I waited for main electric connection. It also gave me a chance to do an actual small scale PV install with inverter, MPPT and batteries. When I came to buy the other 12 panels, the solar panels I had were already end of life and being phased out. But I was able to get the panels I needed. 
 

 

Edited February 10 by Nick Laslett

[Nickfromwales]

  On 10/02/2025 at 10:06, Dillsue said:

We've had a couple of optimisers fail and I've gone direct to SolarEdge for replacements and I think the panel warranty from JA SOLAR would be the same. I don't recall seeing anything in the warranty wording that needed the installer to make a claim.

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Cases vary, just I've spoken to a number of people in the solar industry and clients at various exhibition shows, and gleaned the feedback there.

 

SolarEdge are a very reputable company for eg.

 

Most clients don't know why the system has stopped working, so they need the original installers to come out so that between them they can ascertain what the fault is. Some have been unsuccessful getting certain panel brands replaced, is what I have been told. 

[Nickfromwales]

  On 09/02/2025 at 23:40, G and J said:

Good point. 
 

Presumably that would cover panel only, as opposed to any peripherals like optimisers. 

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Anything should have a min 1 year warranty, just ensure that you are the party that is wedded to it, is all I'm saying vs assume anything  

[G and J]

  On 10/02/2025 at 10:06, Dillsue said:

We've had a couple of optimisers fail and I've gone direct to SolarEdge for replacements and I think the panel warranty from JA SOLAR would be the same. I don't recall seeing anything in the warranty wording that needed the installer to make a claim.

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Were the optimises accessible without taking the panels off?

[Dillsue]

  On 10/02/2025 at 23:44, G and J said:

Were the optimises accessible without taking the panels off?

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Not for me. Unless you mount them inside the roof then they are either integrated into the panel or mounted behind/under the panels.

 

If you or your roofer are confident on the roof then it's only a 15 minute job to lift a panel, swap an optimiser and refix the panel. I have access to a rope and harness so happy to work off a ladder but with an alloy scaffold tower it's a breeze to lift a panel.

[Dillsue]

  On 10/02/2025 at 11:07, Nickfromwales said:

Anything should have a min 1 year warranty, just ensure that you are the party that is wedded to it, is all I'm saying vs assume anything  

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I think most panels/inverters/optimisers have at least a 10 year warranty. JAs warranty is for the end user and transferable to subsequent property owners. I'd guess most mainstream suppliers would be similar??

[Alan Ambrose]

>>> or mounted behind/under the panels.

 

@Dillsue - so you can fit optimisers with in-roof trays OK? Or were you talking about on-roof at that point?

[Nickfromwales]

  On 11/02/2025 at 10:27, Alan Ambrose said:

>>> or mounted behind/under the panels.

 

@Dillsue - so you can fit optimisers with in-roof trays OK? Or were you talking about on-roof at that point?

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We put them on the roof routinely now, as mounting them remotely seems to conflict with MCS ‘good practices’ if adding made up ‘jumper cables’. 
 

 

Note the silver boxes (optimisers) at each tray. 

[Alan Ambrose]

Ah, picture paints 10,000 words. Thanks.

 

Is it a PITA to get your battens spaced so they suit both the tiles and the trays? I've looked at the GSE docs and they make it look v hard.

Edited February 11 by Alan Ambrose

[Nick Laslett]

I quite enjoyed fitting the GSE trays, just a one man job. The PV panels are a little tricker, because they are so unwieldy. You need another person to hold the panel whilst you connect it up. The instructions make it seem harder than it is. 
 

@Alan Ambrose If you zoom in on the photo, you can see the extra batten requirements, not many needed. I let the roofers fix their battens then added the extra ones myself. 
 

@G and J, besides the roof access requirements, it is easy to lift up a PV panel to access the solar diverter. The panels are held on with a few clips screwed into the tray. 

[Nick Laslett]

A more close up photo. 

 

There are lots of good GSE installs on YouTube.

[marshian]

@Nick Laslett have you got any pictures with the in roof install finished?

 

I will at some stage need to strip my south facing roof to replace the felt (Old bitumen style felt from the 80's)

 

I have a small stock of spare roof tiles from when I did the extension (I could still get the original tiles then) but the in roof solar PV looks like I could get away without trying to find seconds to match the existing tiles.

[Nick Laslett]

@marshian, here you go. 
 

You are welcome to visit the site if you want a closer look at the PV install. These panels are on the Cartlodge (garage), so easy to access.