Fixing semi-flexible solar panel

[LittleSister]

I am contemplating fitting a semi-flexible solar panel. These would typically be glued to the supporting surface (in this case a slightly curved wheelhouse roof).

What adhesive could I use that would be sufficiently strong for the purpose, but capable of removal a few years down the line without damage to the gelcoat or leaving unsightly residue?

 

[RichardS]

I am contemplating fitting a semi-flexible solar panel. These would typically be glued to the supporting surface (in this case a slightly curved wheelhouse roof).

What adhesive could I use that would be sufficiently strong for the purpose, but capable of removal a few years down the line without damage to the gelcoat or leaving unsightly residue?

I've just done exactly the same to 4 panels and used a blob of CT1 in each corner. It can be softened with solvent if I ever need to remove it although it won't be easy.

Richard

 

[Gwylan]

Did that with wide double sided velcro. Still there after 4 seasons.

 

[VicS]

I am contemplating fitting a semi-flexible solar panel. These would typically be glued to the supporting surface (in this case a slightly curved wheelhouse roof).

What adhesive could I use that would be sufficiently strong for the purpose, but capable of removal a few years down the line without damage to the gelcoat or leaving unsightly residue?

My first panel was bolted to the deck and also sealed around the edges with silicone sealant as suggested in the fitting instructions, I assume I used a "marine" sealant, not the bathroom stuff., It certainly was not one of the modern adhesive sealants.

When the time came to remove it I broke it into many pieces trying to un-stick it from the deck. The residue was difficult to remove from the deck too.

The new one is just bolted down though grommets in the corners.

 

[Pete7]

Did that with wide double sided velcro. Still there after 4 seasons.

Same here. Homebase do packs of sticky backed pads.

 

[peteK]

I used butyl strip around the circumference of the panel.

 

[PetiteFleur]

I used small countersunk stainless self tapping screws, in each corner and along the edge. Small enough so they did not penetrate the grp - but I did add a small blob of sealant in the hole just in case I'd drilled the pilot hole too deep.

 

[PaulRainbow]

The pair of 30w panels on my coach roof are held down with four self tappers. Been there since 1988.

 

[duncan99210]

The three panels on my foredeck are fixed at the corners with self tappers. Been there for 6 years now.... The previous ones were stick down with Sikaflex and were a real pain to remove. New panels cover the remaining mess. I’ll never use adhesive to fix panels in place again.

 

[AntarcticPilot]

Mine is simply lashed to the guardrails like a canvas dodger. It can be moved easily to whichever side faces the sun, and is at a good angle for the low sun usual in the UK.

 

[blxm]

It won’t need a lot to hold it down. I have 3 panels held to a soft(ish) Bimini with just Velcro around the edges. No sign of moving and they have been battered at times.
If you can find an adhesive that can be removed easily then a dab in each corner should be just fine.

 

[JumbleDuck]

I've just done exactly the same to 4 panels and used a blob of CT1 in each corner. It can be softened with solvent if I ever need to remove it although it won't be easy.

The pair of 30w panels on my coach roof are held down with four self tappers. Been there since 1988.

I have nice new panels waiting to be fitted. If they were going on flat I would use a screw at each corner, but they will both have to be curved (the one on the coach roof rather more than the one on the hatch garage) and am worried about the stresses which will be induced as the edges try to lift.

My current cheapy panels are held down with velcro. That worked quite well, but one velcro strip has mostly lifted off the roof and all the velcro goes a foul green-brown colour with stuff living in it.

I#m therefore watching this thread with interest. So far I have been considering glue, but not Sikaflex, so sticky pads sound interesting, and holding each side down with a teak strip screwed outside the panels to the deck. I don't want to drill new holes through the panels because I would worry about leaks, and I hope these ones will last a long time. They cost €200 each and replace ones which cost £50-ish.

 

[tross]

When I first fitted mine to the hatch garage I just ued the screws holes provide. However, in a bit of blow you could see the wind getting under the panel and vibrating it ! Even more worring in was when I lifted the panel off was the water trapped below it had started to create little bubbles (osmosis) in the gel coat !!!! In the end I sealed it around the edges with Stick like Sh*t acrylic sealant adhesive to prevent both issues. The nice thing about using this is I have found it remains flexible much longer that silicone / other adhesives and sets on damp surfaces.

 

[ghostlymoron]

Vertical is not the optimum even for the UK. Horizontal is much better. For what it's worth, I've always fixed my panels with through bolts through the corner grommets as I don't trust glue (the sea can be an unforgiving environment).

Mine is simply lashed to the guardrails like a canvas dodger. It can be moved easily to whichever side faces the sun, and is at a good angle for the low sun usual in the UK.

 

[dunedin]

Did that with wide double sided velcro. Still there after 4 seasons.

+1. We used “industrial” Velcro - 2 inches wide - to attach panels to sprayhood. Worked perfectly, and survived multiple severe gales without any issue. Removed 2-3 times, which requires a lot of careful pull, but no damage and easily refitted.

 

[AntarcticPilot]

Vertical is not the optimum even for the UK. Horizontal is much better. For what it's worth, I've always fixed my panels with through bolts through the corner grommets as I don't trust glue (the sea can be an unforgiving environment).

Neither vertical nor horizontal is ideal for the UK. If you wish to attain the peak noon insolation, then the angle to the horizontal should be the same as the latitude, and the panel should face due south. However, the average altitude of the sun on a particular day is below the peak altitude, and of course the peak altitude varies between latitude + and minus 23 degrees. I'd argue that the ideal angle in UK latitudes is around 45 degrees for a south facing panel. Domestic installations at roof angles do very well - I get a peak insolation from mine of better than 90% of the maximum, which is close to the theoretical maximum for my latitude (52N ish). Flat has the obvious advantage that it is not directionally sensitive, which is going to be a factor for those on swinging moorings; for me, on a marina berth in a fixed orientation, vertical has advantages - I can arrange it so that the panel is not shadowed at any time of the day, which would be difficult for a flat panel.

PS. The solar calculator I posted on another thread (https://globalsolaratlas.info) makes the optimum angle at my latitude 38 degrees - so my guess wasn't bad!

Obviously, as you move further south, a flatter orientation gains the advantage, but in UK latitudes, I think you can reasonably argue that either is fine, and will not give significantly different results. Indeed, in Scotland, I would imagine (I haven't done the sums) that a vertical orientation is significantly better.

In any case, my method of attachment (lashing through eyelets in the panel) means that I can readily change it to suit circumstances.

 

[ghostlymoron]

I must admit that my comments were based on swinging mooring and fixed installation. I like to generate when sailing so vertical would not work for me.

Neither vertical nor horizontal is ideal for the UK. If you wish to attain the peak noon insolation, then the angle to the horizontal should be the same as the latitude, and the panel should face due south. However, the average altitude of the sun on a particular day is below the peak altitude, and of course the peak altitude varies between latitude + and minus 23 degrees. I'd argue that the ideal angle in UK latitudes is around 45 degrees for a south facing panel. Domestic installations at roof angles do very well - I get a peak insolation from mine of better than 90% of the maximum, which is close to the theoretical maximum for my latitude (52N ish). Flat has the obvious advantage that it is not directionally sensitive, which is going to be a factor for those on swinging moorings; for me, on a marina berth in a fixed orientation, vertical has advantages - I can arrange it so that the panel is not shadowed at any time of the day, which would be difficult for a flat panel.

PS. The solar calculator I posted on another thread (https://globalsolaratlas.info) makes the optimum angle at my latitude 38 degrees - so my guess wasn't bad!

Obviously, as you move further south, a flatter orientation gains the advantage, but in UK latitudes, I think you can reasonably argue that either is fine, and will not give significantly different results. Indeed, in Scotland, I would imagine (I haven't done the sums) that a vertical orientation is significantly better.

In any case, my method of attachment (lashing through eyelets in the panel) means that I can readily change it to suit circumstances.

 

[ghostlymoron]

On revisiting this thread I'm wondering how people fix their velcro to fabric or GRP.

 

[scrambledegg]

If using velcro I think you'll have to be sure that the panel won't ever get stepped upon, because that's likely to cause the panel to locally exceed its flexibility limit and be damaged. Maybe not a good idea on the OP's roof.

 

[LittleSister]

A belated thanks for all the suggestions.

If using velcro I think you'll have to be sure that the panel won't ever get stepped upon, because that's likely to cause the panel to locally exceed its flexibility limit and be damaged. Maybe not a good idea on the OP's roof.

Yes, that was one of the concerns that ruled out Velcro for me, as I do need to stand or kneel on this surface at times.

I also abhor self-tappers into fibreglass, and would rather not through bolt in this particular instance (because of what's inside below) if possible to avoid.

My current thinking is -
1) Panel bolted to Bigfoot or similar stud fitting at each corner, and those fittings glued to GRP wheelhouse roof with some adhesive that could be softened/cleaned off with solvent after several years (suggestions for such an adhesive invited); and
2) Rather than just edges sealed, whole panel (excepting the above fittings) bedded on thin layer of butyl sealant. In my imagination this would (a) hold the panel more securely (by air pressure); (b) reduce the likelihood of the reverse side blistering due to continuous contact with water; and (c) reduce the local flexing in way of the Bigfoot fittings if (despite intention of avoiding) the panel is stepped or knelt on very close to them.

Any comments on this cunning plan?