Which Velcro / hook & latch for flexible solar panels

[Capt.Don]

I am so confused; what I thought would be a simple search for Velcro to secure flexible solar panels to my bimini is turning out to be difficult. What I'm trying to do is follow the advice from marine how to to sew "lapels" with adhesive Velcro on the top and bottom of the solar panels and corresponding sew-on Velcro on the fold-over lapel.

It seems like various websites suggest "Industrial Strength" Velcro. Where it gets confusing is this is a nylon based product, where Sailrite and others recommend polyester (better UV, water resistance....). To complicate things, even in the Velcro line, there's different hook and loop strengths and different adhesives.

I need both sew-on and adhesive hook & loop around 30' with the sew-on hook/loop working with the adhesive same loop/hook.

One option would be to use sew-on for both sides and use double-sided tape to attach to the panels and velcro. That way I could use polyester, without worrying about different hook & latch patterns, etc... Which double-sided tape would you recommend?

Any other recommendations? Thanks,
Don

[wyb2]

Originally Posted by Capt.Don

…
It seems like various websites suggest "Industrial Strength" Velcro. Where it gets confusing is this is a nylon based product, where Sailrite and others recommend polyester (better UV, water resistance....).
…
Don

I don’t think this part is confusing - the nylon is likely stronger, but the polyester will likely hold up better over the long term when used outdoors. Lots of “industrial” applications are indoors.

If you are sewing a lapel, with velcro on both the top and bottom of the panel, the strength of the Velcro connection is almost irrelevant. The only peeling action will be the wind trying to get under the downwind lapel, and this isn’t very high. Any action of the panel trying to lift off the bimini will create shear loads in the velcro connection, where it is an order of magnitude (or two) stronger than in peel.

The important thing is an adhesive that will stay stuck to the panel, through temperature swings and over time.

[GordMay]

Polyester hook and loop is recommended, for most outdoor projects, and [specifically] on boat canvas.

VELCRO® Brand Hook 81 [male] is made of polyester, and resists moisture, and ultraviolet light, making it great for outdoor use. It is available in widths up to 4 inches, and works best when paired with [female] Loop 9000.
Hook 81 also meets specification under military commercial item description AA55126 (Rev. C).
➥ https://www.trivantage.com/velcro-br...ck-item-580113


The strength of a hook and loop combination is measured in three ways.
Shear strength refers to the tensile strength of the hook and loop engagement, when held on opposite ends, and pulled apart at 180 degrees, parallel to the connection.
Tension is measured the same way as shear strength, except the sides are pulled apart evenly, from each side, perpendicular to the connection.
Peel strength is measured by pulling the hook and loop engagement apart, on the same ends, at 180 degrees, perpendicular to the connection.

Hook 81 only has a medium cycle life, when paired with polyester Loop 9000; but this shouldn’t be a major factor, since your application should only require occasional adjustment/engagement [open-close cycles].
If the fastener will undergo frequent openingsm and repositioning, higher cycle life is needed. If a closure is exposed to harsh outdoor conditions, with infrequent openings, then a low cycle life [high strength] fastener is suitable.

[CaptTom]

I've seen posts where people recommend strong magnets instead of Velcro. Seems like that would work even better. Thinking about either option, though, I'd want some sort of air gap between my Bimini and the panel. Not really sure on the best approach there.

[Capt.Don]

The more I think about this, I'd like to go with sew-on polyester and stick to the panel & velcro with a double-sided tape. Any suggestions on tape similar to what's on the Velcro industrial adhesive?

[Capt.Don]

Originally Posted by CaptTom

I've seen posts where people recommend strong magnets instead of Velcro. Seems like that would work even better. Thinking about either option, though, I'd want some sort of air gap between my Bimini and the panel. Not really sure on the best approach there.

Good point. The panels were too hot to touch after leaving in the yard for a few hours....

I might get lucky with my install. The outside edges sit on or near the bimini frame. The lapel + velcro will create a bit of gap. I'll have to check how the panels sit on the inside, though. My previous install (temporary 5 year solution) used 1/2 of pool noodle to raise the panels and prevent chafe. Perhaps I'll do something similar on the inside edge.

Don

[Capt.Don]

Just to close off this discussion, McMaster-Carr has polyester hook & loop with acrylic adhesive.

[jpendoley]

I just finished installing 400W of flexible panels on my bimini and the approach has worked well. This forum provided the concept that I went with. Because the panels are known to get hot and to protect the bimini, I mounted a sheet of corrugated acrylic to the bimini frame on Gemini Canvas post mounts. The post mounts are screwed to the frame through the canvas-the bases of the posts are saddlemounts and cover the bolt holes. Gemini Canvas is a Maine based canvas shop that has developed a line of mounts for canvas work.
The post mounts are stainless and well built. Installing the post mounts does involve tapping the bolt holes in the saddles with a 10/32 tap-tedious, but secure.
The acrylic sheet idea I got from this forum: it is corrugated so it allows air flow beneath the panels which are fastened to the acrylic which is mounted to the posts projecting 1" above the bimini fabric. The acrylic is available at Home Depot or Loews. The bimini and the acrylic never get warm. The acrylic sheet mounted on the posts bends to follow the curvature of the bimini frame such that the flexible panels are
not noticeable from almost any viewing angle or distance.
I would be hesitant to recommend two sided vhb tape-that was my first effort (I always seem to do every boat project twice....). The Dow VHB tape is so aggressive it does not allow adjustment of panel position. I spent two hours carefully cutting my panels away from the tape because an initial misalignment caused the panels to stick ferociously to the plastic subpanel. I finally settled on bungee cord threaded through the panel grommets and the underlying acrylic. Its completely secure and can be removed in minutes. If preparing for really heavy weather I would cut the bungee cord to remove the panels and dismount the acrylic so I could fold and lash the bimini and frame. Dismounting the acrylic would require unbolting 18 flat head screws that secure the acrylic to the posts-easily accomplished with a cordless drill. The bimini frame with the bimini still attached could then be folded back and the bimini fabric wrapped with line to protect against sredding in really heavy weather.
I accomplished all of this before my annual Maine cruise...Sitting in Linekin Cove batteries at float by 10 AM running laptops, reefer, autopilot and starlink without draining the house bank.

[jpendoley]

Hers a couple of pictures of the above arrangement. Tb tape-its a runner up for devil glue. There is unoccupied acrylic where I could add another panel. The only down side: I hate the cabling-thinking and wondering how to better cable the panels-four panels in two arrays wired in parallel amounts to a lot o MC4 connectors....wondering if I should have used sheathed two conductor cable instead and may try that....

[s/v Jedi]

Industrial grade holds up to 10 pounds while extreme outdoors grade holds up to 15 pounds so that’s what I would use. It doesn’t matter much because it only has to last as long as the panels…

https://www.amazon.com/VELCRO-Brand-.../dp/B09BNPHCZX

In the description they call it industrial grade again

[thinwater]

Originally Posted by Capt.Don

I am so confused; what I thought would be a simple search for Velcro to secure flexible solar panels to my bimini is turning out to be difficult. What I'm trying to do is follow the advice from marine how to to sew "lapels" with adhesive Velcro on the top and bottom of the solar panels and corresponding sew-on Velcro on the fold-over lapel.

It seems like various websites suggest "Industrial Strength" Velcro. Where it gets confusing is this is a nylon based product, where Sailrite and others recommend polyester (better UV, water resistance....). To complicate things, even in the Velcro line, there's different hook and loop strengths and different adhesives.

I need both sew-on and adhesive hook & loop around 30' with the sew-on hook/loop working with the adhesive same loop/hook.

One option would be to use sew-on for both sides and use double-sided tape to attach to the panels and velcro. That way I could use polyester, without worrying about different hook & latch patterns, etc... Which double-sided tape would you recommend?

Any other recommendations? Thanks,
Don

I also suggest you research flexing of panels and support. If they flex repeatedly they will fail prematurely and have been known to start canvas fires. If you read the manual they will say they can flex ONCE, but should be supported on a rigid structure, such as a curved deck. They are not really made for canvas, but most ... get away with it. The problem is that the cells are still crystals, but now they don't have the support of glass. They fatigue and crack with repeated bending, and the cracks can be too small to see, but they sap power and risk overheating. Buffing is also known to destroy panels (the flexing under pressure).



Better panels do better because they are stiffer. But Read the manual!!



I have gotten good life from a cheap semi-flex panel, but it is screwed to the the deck.

[s/v Jedi]

Originally Posted by thinwater

I also suggest you research flexing of panels and support. If they flex repeatedly they will fail prematurely and have been known to start canvas fires. If you read the manual they will say they can flex ONCE, but should be supported on a rigid structure, such as a curved deck. They are not really made for canvas, but most ... get away with it. The problem is that the cells are still crystals, but now they don't have the support of glass. They fatigue and crack with repeated bending, and the cracks can be too small to see, but they sap power and risk overheating. Buffing is also known to destroy panels (the flexing under pressure).



Better panels do better because they are stiffer. But Read the manual!!



I have gotten good life from a cheap semi-flex panel, but it is screwed to the the deck.

Your panel is on fire

[thinwater]

Originally Posted by s/v Jedi

Your panel is on fire

Thankfully, not my panel.


It's not hard to Google failed semi-flex panels on biminis. Worse if they cross a bow.

[Capt.Don]

Copper Indium Gallium Selenide (CIGS) panels handle curves and flex better, claim to be more durable. BougeRV has narrow 100w panels that fit my bimini. My initial test confirms they are not as efficient as my older 100w flexible panels (17%) and do run very hot. Getting ready to install with Velcro.

[Rohan]

This is the velcro that I used:

https://www.amazon.com/gp/product/B0006HWYJM/?th=1

And it's strong. It's almost too strong - it was difficult to remove the remove the panels when I wanted to take them off! I still tie the edges of the panels to something just in case of storm winds, but I probably don't need to.

There is glue on both parts of the velcro, and it firmly sticks to the panel well. On the bimini fabric it does help hold it in place while you sew it in, however the glue can gum up the sewing machine. You can use Goo Gone or a similar product to remove the glue first to make that easier. But we just powered through it.

I don't see how UV protection would matter, since it's entirely underneath the panel and blocked from the sun.