Solar panel sticky stuff. A test.

[Emmit]

Hi All,

A couple of weeks ago I had fun and games, moving and sticking down three solar panels on the roof of the 'van.
Prior to doing the deed I spent a lot of time on here, reading the merits of various adhesive/sealants to do the job.

With dire reports of solar panels flying off on the Motorways I decided to use Puraflex 40. Although made by the same firm that make Sikaflex in all its various forms and coming in at half the price of some products advocated on Fun, I did wonder whether I had chosen wisely.
As a result I decided to do a test. Nothing scientific, but something to put my mind at rest.
When I made the brackets for the panels, I had some ally sheet left over. I made, with two of the pieces, something that could be used to test the efficacy of of the glue. I formed and made something that could be screwed to a garage joist with a second piece of ally glued to it with Puraflex with a 2_3mm bead. The second piece was shaped so as to accept a rope.
Here are photos.

This shows the piece I made.
The next photo shows how it would fit on a joist.

I hope all this is making sense?

Anyway, the test. I threw a rope over the hook and attached 2 x 5lt tins of deck/fencing paint. They weighed approx 11kgs.
I left the tins on the rope and, left it dangling for two days. The photo of the piece was taken AFTER I did the test.
The surface area of the Puraflex was approx 55mm x 55mm.

Conclusion. If that adhesive can hold a constant weight of 11kgs without any sign of separation after two days I feel confident that there are two chances of it coming adrift on top of the 'van. Fat chance and no chance at all, especially as there are five points of contact holding each panel.

 

[PhilandMena]

And the Sikaflex test results ?

 

[Emmit]

I tested what I used. It was made by Sikaflex.
I'll test All!!! the Sikaflex products if someone provides them.

 

[bobandjanie]

It's always a worry when you have to much time on your hands.
Did you sleep well, I would have been dreaming about the big clean up, because the lids popped off. Bob.

 

[DBK]

I guess that was a bare metal to bare metal test? If you glue it on the roof of the MH I assume you won't be rubbing it down to bare metal. So it just depends how well the roof finish is stuck down.

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[Jimbohorlicks]

It's not the roof it's stuck to its just a film of paint

 

[Emmit]

I guess that was a bare metal to bare metal test? If you glue it on the roof of the MH I assume you won't be rubbing it down to bare metal. So it just depends how well the roof finish is stuck down.

Metal! Metal???
No, it was fibre glass that was cleaned to within an inch of its life.

 

[Emmit]

It's not the roof it's stuck to its just a film of paint

There was no paint on the roof under the Puraflex.

 

[Emmit]

It's always a worry when you have to much time on your hands.
Did you sleep well, I would have been dreaming about the big clean up, because the lids popped off. Bob.

It put the 'willy's' up me as well.
That's why the tins were hovering so close to the floor, a mouse would have had trouble crawling underneath.

But thanks for thinking about me.!!!

 

[Pete5996]

I formed and made something that could be screwed to a garage joist with a second piece of ally glued to it with Puraflex with a 2_3mm bead. The second piece was shaped so as to accept a rope.

Phew, I thought for a moment that the lockdown was finally getting to you....

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[DBK]

Metal! Metal???
No, it was fibre glass that was cleaned to within an inch of its life.

Should be fine then. But it is a serious point, the paint on the roof of my PVC has detached in a few places. I used Sikaflex but added self-tappers.

 

[Emmit]

Should be fine then. But it is a serious point, the paint on the roof of my PVC has detached in a few places. I used Sikaflex but added self-tappers.

I put the solar panels on the roof, complete with legs and drew around them. I then scoured those area's with wet and dry then swabbed the area with alcohol 96 percent.

 

[Lenny HB]

A static weight test is nothing like the force on them in use. You need to calculate the lifting effect of wind lift when driving at 70mph into say a 50mph headwind. The force on them will probably be a few hundred times your static test.

 

[Lenny HB]

Reminds me a few years ago I was fitting some screens in a BT call centre, they got another company in to fit the ceiling mounts (we were too expensive). They then had another company in to do a static weight test before we were allowed to fit the screens. We arrived looked at the fittings gave then a tug told them it was not safe to fit too and left.

 

[Emmit]

Lenny HB
While I agree that a static test proves nothing.

I do know however, that the the top of the panels are flat and not curved. I also know that the distance between the two edges of the panels both top and bottom are the same. As a result there will be no difference in pressure above or below them and theoretically no 'lift' as one would get with, say, an aeroplane wing.

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[Geo]

I put the solar panels on the roof, complete with legs and drew around them. I then scoured those area's with wet and dry then swabbed the area with alcohol 96 percent.

At least you ain't trapped any Covid under your plates

 

[Emmit]

Should be fine then. But it is a serious point, the paint on the roof of my PVC has detached in a few places. I used Sikaflex but added self-tappers.

Could it be, that the problem is that your PVC body is a mass manufactured unit. I have had problems myself with the paint on our coachbuilt, BUT the problem was on the bonnet of the Fiat and I have seen lots of examples of paint 'falling' off that item.

 

[9526]

A static weight test is nothing like the force on them in use. You need to calculate the lifting effect of wind lift when driving at 70mph into say a 50mph headwind. The force on them will probably be a few hundred times your static test.

Im struggling to believe your theory that the lifting force on a roof mounted solar panel will probably be a few Tonnes.

 

[bobandjanie]

Next project build a wind tunnel .

You know how well they are stuck on, when you try to get them off. Bob.

 

[Lenny HB]

Im struggling to believe your theory that the lifting force on a roof mounted solar panel will probably be a few Tonnes.

Just trying to point out a static load test is worthless, need to get an aero engineer to do the calculations.

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[Gellyneck]

...........The force on them will probably be a few hundred times your static test.

Wonder if the OP wants me to go down and stand on his rope for a day or two for him to give a real world test result?

 

[BusyBuilder]

I stick wet wall 2400 x 1200 sheets to bathroom walls, some of these walls are not straight. I use those expanding bars (bit like light weight acrows) to push the 12mm marine ply wet wall to the wall. I use the dot and dab method on the panels.

Not had one come off yet, and only use Sticks Like https://www.screwfix.com/p/evo-stik-sticks-like-sh-t-adhesive-290ml/22070

I have fixed 3 solar panels on 2 Hymer roofs using this and those large plastic corners, Amazon product ASIN B009X7WKR2they are still stuck down. Sometimes you can overthink things.

 

[Mr Chrysalis]

A static weight test is nothing like the force on them in use. You need to calculate the lifting effect of wind lift when driving at 70mph into say a 50mph headwind. The force on them will probably be a few hundred times your static test.

I was trying to work out how to say the same thing. You need to take account of the lateral force which will apply a shear force on the joint combined with the lift caused by the wind over and under the solar panel - this will have a tendancy to act like a wing, and remember that is strong enough to lift a Jumbo Jet! Think about how you would separate two things stuck together. You don’t just pull on them, but you naturally twist ( shear force to break the adhesion ) whilst you pull (lift).

 

[Mr Chrysalis]

Lenny HB
While I agree that a static test proves nothing.

I do know however, that the the top of the panels are flat and not curved. I also know that the distance between the two edges of the panels both top and bottom are the same. As a result there will be no difference in pressure above or below them and theoretically no 'lift' as one would get with, say, an aeroplane wing.

Yes, true if the panel is perfectly aligned with the wind, but any slight angle will create lift, think of flying a kite.

this work is similar but not exactly the same

https://res.mdpi.com/d_attachment/energies/energies-08-02438/article_deploy/energies-08-02438.pdf

 

[68c]

Aviation breakthrough, we no longer need to use super critical NACA profile airfoil shaped wings, just screw a couple of solar panels to the fuselage.

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[tonyidle]

You need to take account of the lateral force which will apply a shear force on the joint combined with the lift caused by the wind over and under the solar panel

No ......... we simply need to stop over-thinking it. Just stick clean surfaces together using PU adhesive. It works. My experience is of installing panels on 4 vans. Twice used Sikaflex and twice used Tigerseal. Adhesion checked visually and with a light tug once a year when cleaning the roof. No issues, no separation, no panels lost. Has anyone on the Forum ever had a panel come loose because of adhesive failure?

Wind passing over / under the panel will tend to pull it onto the roof (air will speed up under the panel because of the small gap). Wind hitting the front edge will attempt to push the panel towards the rear of the van.

 

[Lenny HB]

Has anyone on the Forum ever had a panel come loose because of adhesive failure?

2 or 3 have, they all had plastic brackets and used the wrong Sika, one of the common Sika's used for aluminium brackets is not suitable for plastic.

 

[tonyidle]

2 or 3 have, they all had plastic brackets and used the wrong Sika, one of the common Sika's used for aluminium brackets is not suitable for plastic.

One of the reasons I don't like plastic brackets. Apart from the excessive cost they introduce variables and need care to ensure all mould release is removed.

 

[Emmit]

No ......... we simply need to stop over-thinking it. Just stick clean surfaces together using PU adhesive. It works. My experience is of installing panels on 4 vans. Twice used Sikaflex and twice used Tigerseal. Adhesion checked visually and with a light tug once a year when cleaning the roof. No issues, no separation, no panels lost. Has anyone on the Forum ever had a panel come loose because of adhesive failure?

Wind passing over / under the panel will tend to pull it onto the roof (air will speed up under the panel because of the small gap). Wind hitting the front edge will attempt to push the panel towards the rear of the van.

That was my thought. Call it 'Lockdown fatigue' if you want but I had the spare ally and it occured that I've never seen a 'Shed' experiment on here so I went for it.

I will, when I have completed my next list of jobs forwarded by 'Management', do the experiment again with significantly increased loads (I will not be asking management to take part in the 'Load' provision) and we'll see how far that little spread of adhesive can be pushed.

 

[Emmit]

Wonder if the OP wants me to go down and stand on his rope for a day or two for him to give a real world test result?

I could do a static test with 'Management'.

The difficult part will be to get her to stand on the rickety stool while I tie the rope around her'''''''''
(There's No way that the QC for the prosecution could find this post, or is there? )

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