Aluminium Angle for mounting Solar Panels?? (1 Viewer)

Oct 8, 2014
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Help!!! .... I am confused!

I am just about to fit a 100W Solar panel to my MH. I have bought 4 x lengths of 300mm long 2.1/2" x 2.1/2" x 1/8" Aluminium Angle, together with Sikaflex 512 and Sika 205 Activator.

However in a post about cleaning under solar panels, I received this reply:

"Don't use bare aluminium directly on the roof. Use anodised or stainless steel then you can attach them without screws. Adhesive eventually lets go of bare aluminium because the oxide layer to which it is stuck absorbs water & corrodes the aluminium. You can also get plastic corner mounts that can be stuck to the roof."

I have read numerous posts on this forum regarding using Aluminium Angle, and have never seen this warning before. Also there is no mention of it on the various Sika Data Sheets I have read - including their pre-treatment one - even though it does not mention Sikaflex 512 directly. https://usa.sika.com/dms/getdocument.get/4c07225f-6914-3451-9f4b-ad1cf9cbfbed/Primer%20Chart%20PU%20Sikaflex%20200.SikaTack%20Series.pdf

Should I be looking at an alternative bracket material?
 

mid4did

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to oxidise aluminium needs oxygen,if it's sealed with sikaflex then surely it cant IMO.(y)

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Techno

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I've never witnessed any evidence of that and Sikaflex is designed for direct use on bare aluminium. Carry on.
 

DBK

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Some quick googling suggests the aluminium oxide does reduce the bond strength by up to 50% but given the area you are considering this won't matter a jot. I can't see a long term problem either, bonding aluminium is a common practice and it wouldn't be done if the joints fell apart afterwards.

I would just roughen the aluminium with fine sand paper first. I also used screws on mine in addition to the Sikaflex. :)
 

Terry

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Can't remember ;)
I'll reserve judgement for around 15 yrs -that is the oldest I have taken off and examined --I found and warned of some Sikaflex not sticking to some plastics -letting go after 3-4 yrs ;)

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Revolvor
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Thanks guys for all the reassurance.... I will proceed as planned.
 

Techno

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These will come unstuck for sure if the boding surface hasn't been scoured with wire wool and cleaned with sika 205 or equivalent
image.jpeg

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Revolvor
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These will come unstuck for sure if the boding surface hasn't been scoured with wire wool and cleaned with sika 205 or equivalent View attachment 104426
@Techno - Andy, where do you get these cable entry boxes? Most of the ones I have seen are much larger.

Also, what is the typical time interval between applying the Sika 205 and the Sika 512?
 
Last edited:
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I used Sikaflex and some self tappers. I put spacers between the base of the aluminium angle and the roof to ensure a 2mm gap was kept when I screwed down.
5 years and counting. This is on a PVC though.
 

Terry

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Can't remember ;)
More often because the plastic wasn't prepared correctly before applying adhesive
Probably Andy but I know the plastic was prepared right I did it(y) and two yrs later it let go -noticed it could move so I pulled it off and used other stuff that it stayed stuck with :)

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Aug 6, 2013
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My experience with aluminium corrosion is admittedly on small parts - I suspect a decent area would be fine. Having said that I wouldn't use it. Mine are on 1mm stainless 'L' section bent up for me by a local metalworks. Little difference in price (to me - the owner is a good friend).
 
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Machined Aluminium starts to oxidise within thirty minutes, so to get a good surface bond scotchbright the faces before applying your chosen adhesive and it should in theory last as long as it takes the adhesive to start to decompose.
 

vwalan

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for about the last 5 years when i have fitted solar panels i have used white plastic angle .
i find some of the local builders are happy to let people use off cuts and only want a drink for them . it seems to work ok. havent had any probs yet.
mind mine is on with ally and have been for 14 yrs . well the first three still no probs .

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Kool Kroozer

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I stuck 2 140w panels on our roof with sikaflex 512 using raw aluminium angle, i do stick my head through the roof lite now and again and give em a tug to see if there is any movement - as of yet none - still solid
 
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Revolvor
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My experience with aluminium corrosion is admittedly on small parts - I suspect a decent area would be fine. Having said that I wouldn't use it. Mine are on 1mm stainless 'L' section bent up for me by a local metalworks. Little difference in price (to me - the owner is a good friend).
In hindsight, I would have preferred Stainless, but a) it is more expensive, and b) I already have ordered the aluminium!

Machined Aluminium starts to oxidise within thirty minutes, so to get a good surface bond scotchbright the faces before applying your chosen adhesive and it should in theory last as long as it takes the adhesive to start to decompose.
I plan to scotchbrite and apply Sika 205 immediately, and then the adhesive as soon as the Activator is dry.

for about the last 5 years when i have fitted solar panels i have used white plastic angle .
i find some of the local builders are happy to let people use off cuts and only want a drink for them . it seems to work ok. havent had any probs yet.
mind mine is on with ally and have been for 14 yrs . well the first three still no probs .
I think I'd be a bit nervous about plastic angle for structural purposes, but thanks anyway.

I stuck 2 140w panels on our roof with sikaflex 512 using raw aluminium angle, i do stick my head through the roof lite now and again and give em a tug to see if there is any movement - as of yet none - still solid
I plan to do the same!

Thanks guys for all your constructive and helpful comments.

John
 

ShaKen

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Resurrecting an old thread......

I’ve installed a 200W panel (113mm x 99mm) on my MoHo using Sikaflex 292i and plastic corner feet; with additional intermediate feet on the longest edge.

To prep, I used Sika Activator and Primer on the roof and feet. I also used a scotchbrite pad on the feet.....BUT I didn’t use a scotchbrite pad on the roof!

The roof area was cleaned in advance with a magic sponge (which does act as a micro abrasive) - but clearly it wasn’t roughly abraded.

However to be SUPER safe I’m thinking of adding Aluminium angle (60mm x 60mm) along the full length of the sides with a full prep’d and primed roof (polyester GRP) and aluminium angle.

Do you think that a) Wise idea or b) Overkill?

Here’s the current install:

A4D557F5-00A2-4436-93BE-8A1CE744BF1F.jpeg

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Aug 6, 2013
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There is going to be a lot of panels flying off roofs :)
Including mine. I haven't followed my own advice re stainless and I've never had problems. I've a feeling I wrote that having just seen a very corroded bracket that was used to mount an aerial. Corrosion had crept part way under the adhesive. However it wasn't mine and I've never had the problem. So ignore my 2016 post ?.
 
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Would you not be better fitting some sort of wind deflector along the front edge of the panel?

This should stop the force of the 60-70 mph 'wind' getting underneath the panel when travelling down the motorway.

I understand that there are proprietary deflectors produced for this purpose, but can't immediately see one online.

Barry
 
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Resurrecting an old thread......

I’ve installed a 200W panel (113mm x 99mm) on my MoHo using Sikaflex 292i and plastic corner feet; with additional intermediate feet on the longest edge.

To prep, I used Sika Activator and Primer on the roof and feet. I also used a scotchbrite pad on the feet.....BUT I didn’t use a scotchbrite pad on the roof!

The roof area was cleaned in advance with a magic sponge (which does act as a micro abrasive) - but clearly it wasn’t roughly abraded.

However to be SUPER safe I’m thinking of adding Aluminium angle (60mm x 60mm) along the full length of the sides with a full prep’d and primed roof (polyester GRP) and aluminium angle.

Do you think that a) Wise idea or b) Overkill?

Here’s the current install:

View attachment 384495
That looks neat.. ?

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ShaKen

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That looks neat.. ?

Thanks!

Expanding my question.....

If I do choose to add additional Aluminium Angle brackets, should I:

a) Add 2 brackets per side, say 10cm long (60mm X 60mm Aluminium)

like this...

7556F2D5-F692-4812-A9F6-53A2679FE91E.jpeg


Or

b) Add 2 brackets on the nearside, offside sides of 60cm long

like this...

5A435AF0-2C87-4F01-92AE-3EBBBEF09417.jpeg
 
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Revolvor
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ShaKen As the originator of this thread, 6 years ago, I can confirm that my panels are both still on! Regarding your question, I would say that option a) is overkill. I would suggest option b), but with shorter lengths of angle, and then fit a deflector of some sort, as suggested by namwaldog

IMG_20200503_141412122_HDR.jpg
 

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