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To Tile below PV panels or not to tile that is the question...


MikeSharp01

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While I have my lunch, the PB has just arrived so an afternoon for getting some of that to the garden room awaits, I am pondering on to the next step for the garden room which is the tiling of the roof. The front elevation has, will have, 16 solar panels which covers 90% of the available space and I am wondering if I should bother tiling under the panels and if not what do I put under them to catch the water that will run off as I am not sure I want to rely on the membrane long term. The tiles are Marley Thrutone in case that makes any difference.

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If you're fitting PV panels in the roof, then they will fit to flashing frames (rather like roof window flashing kits) that secure to the tile battens and the panels then fix to them.  This has advantages over fitting them on the roof, i.e. over the top of tiles, in that it looks neater and it also prevents birds nesting under the panels.  Panels fitted on top of tiles need to be fitted to frames, and this leaves a gap under the panels big enough for pigeons to get in and nest.  We have some friends who are plagued with birds nesting under their panels, and last year they even managed to disconnect one of the DC connectors when raking out all the old nests, which entailed getting scaffolding put up to remove the panels, remake the connection and refit the panels.

 

The cooling issue seems to be minor, as the in-roof kits have a lot of ventilation space underneath, and there should be a good flow of air up under the panels and tiles and out through the ventilated ridge vents.

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1 minute ago, MikeSharp01 said:

Nope not yet, have been looking for one but I can get away without for the garden room a nothing to high and a simple batten frame will sort it.

 

Sorry I meant a "lifter" / carrier for carrying full boards around on your own. The is the one I have:

 

http://www.axminster.co.uk/axminster-panel-board-carrier-950130

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21 minutes ago, MikeSharp01 said:

Is that a reg or something?

 

 

There's no easy way to fit panels over an untiled area, unless you use an in-roof kit.  I guess you could faff around and lay something like an EPDM section, suitably flashed to the tiles all around, where the panel mounting frames are going to be bolted down, but frankly it would be a lot easier to just fit in-roof kits, as they are dead easy and quick to install, and are probably cheaper than either tiling underneath or fitting some sort of waterproof membrane.

 

Having seen the mess nesting pigeons can make under on-roof panels, I don't think I'd want to consider fitting them unless I had no choice.

Edited by JSHarris
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36 minutes ago, JSHarris said:

There's no easy way to fit panels over an untiled area, unless you use an in-roof kit. 

Might be able to help there as the I have been working on a plan where panels will be on a aluminium frame that tilts so I can get to 40deg from the 17deg that the roof is normally. I have 8 points on the roof suitably supported from below for this, my original plan was to make some aluminium (6mm) tile sized plates on which the brackets for the frame bolted, they would just slot in like normal tiles. The lower set of four carrying the bearing and the upper set of four carrying the linear actuators that will tilt the frame. (I think the whole thing including the frame weighs in at around 220Kg although the weight is only one problem as the lift, in a good gales, will not be insignificant in they happen to to be tilted.)

 

Having said all that looks like tiling is the simple solution.

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15 minutes ago, MikeSharp01 said:

so I can get to 40deg from the 17deg that the roof is normally

A quick look at PVGIS shows that for a 1 kWp, south facing, system in Milton Keynes, there is only 3.4 kWh/year difference (73.7 kWh/year @17°, 77.1 kWh/year @40°).

So really just random variation and statistically insignificant.

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Sounds like an argument for using one of the in roof systems from

 the likes of GSE or Easyroof as it not only saves you the roof covering it also saves you the frame fittings. 

 

Caveat to that is to check that they can go down to 17 degrees ...

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16 hours ago, MikeSharp01 said:

Ok so will forget the tilt it is a windage nightmare anyway. So think I will go EPDM under the cells and tiles round the edges. Cheaper that way at least. Thanks all - another problem solved! ( the dreaded exclamation mark again - Trump style.)

 

Probably cheaper, and very definitely a great deal easier, to fit in-roof flashing units and just slot the panels in to them.  They are much easier to install than rails and frames to fix the panels too, won't need bolts that have to be sealed through an EPDM membrane, fix directly to tile battens with normal membrane underneath and make for a very neat installation.

 

The two biggest manufacturers are Easy Roof and GSE Integration, both French (because of French regulations on fitting panels).  Here are the links:

 

http://en.irfts.com/easy-roof-evolution/

 

http://www.gseintegration.com/en/inroof.html

Edited by JSHarris
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