How to attach flexible solar panels to canvas

[skunther]

What is the best way to attach flexible solar panels to biminicanvas? I understand I should get non adhesive backed hook and loop (2” strips), sew the loop side to the canvas and adhere the hook side to the panel with something like 3M 4000. Does this sound like an adequate setup?

Any recommendations on specific hook and loop/adhesive?

The panels are 28”x18”, and I will attach 4 of them due to split backstay configuration: Amazon.com

I’m figuring on maybe attaching lines to corner grommets of the panels for backup, though I would need to find suitable attachment points on the Bimini.

We cruise in the Salish Sea.

 

[fred1diver]

What we do on our Dodger is very simple, on Amazon you can find magnets with screw studs, you use those on the panels and get good magnets for under the canvas, I will try to find the Amazon links for you.
We have used these for over 3 years now and zero issues, very strong, no glue, sewing or anything else, it is very strong, easy to install and remove, and you can drop your canvas in the laundry after

 

[fred1diver]

these are what we use.

 

[skunther]

What we do on our Dodger is very simple, on Amazon you can find magnets with screw studs, you use those on the panels and get good magnets for under the canvas, I will try to find the Amazon links for you.
We have used these for over 3 years now and zero issues, very strong, no glue, sewing or anything else, it is very strong, easy to install and remove, and you can drop your canvas in the laundry after

I actually have 2 panels secured in the same way. I’ve viewed it as a short term install before I could get the hook and loop sewn on.The issue I see with the magnet bolts is that the threaded bolts and nuts are rusting pretty badly after one year. Do you have a rust issue as well?

 

[BarryL]

Hello,

Last year I added 2 solar panels to my dodger. One of my friends suggested sewing a zipper onto the solar panel and to the dodger. I had my canvas guy do that and it works well. Its east to install and remove the panels and they are very secure.

My only regret is that the panels I bought were cheap units and I don't expect them to last more than another year or two.

Barry

 

[fred1diver]

Yes K do have some rust on them, but it is on top, so I do not see it, but you could always paint them

 

[Foswick]

I am a big proponent of industrial velcro. One major reason is that it doesn't fail suddenly and it tends to self-heal. When it ultimately wears out, it is easily, inexpensively, and non-destructively replaced. I had a solar panel attached to a hard surface with velcro, years ago, and it was completely secure. The only real downside was that I had slide a little putty scraper or something in between the hook and loop surfaces to remove it because the grip was too strong to just pry the panel off.

As for 3M 4000, that's probably overkill. If you buy Velcro brand that is for outdoor use (I think it goes by a few names), the adhesive on that tape will definitely adhere to the panel. That isn't the problem. The problem is the canvas side. The adhesive on the tape would "probably" remain fixed to the canvas, but I would sew it on. My service dog's life vest has patches that are attached with velcro that adheres to the vest with just that adhesive. They endure quite a bit of abuse and hold fast, but I don't know that I would trust that to mount a solar panel - especially since it would be easy to just sew the velcro to the canvas.

I would have some concern over magnets interfering with the compass. Some people have an absolute rule about magnets on the boat, though I think this aversion is overemphasized.

One other half-thought is that you could mount the panels to another piece of canvas - just slightly larger than the panels themselves. Then, mount that canvas to the bimini using whatever you like - zipper, snaps, whatever.

 

[AaronD]

I actually have 2 panels secured in the same way. I’ve viewed it as a short term install before I could get the hook and loop sewn on.The issue I see with the magnet bolts is that the threaded bolts and nuts are rusting pretty badly after one year. Do you have a rust issue as well?

I've used adhesive-backed magnets; somewhat less hardware to rust. The solar panels are smooth, and the adhesive seems to work well for us. But we only moor in the summers, so no really-long-term experience (probably a total of < 1 year of usage).

 

[JoeWhite]

Here is how I attached 100 watt flexible to the dodger top with lines only.

Solar Panel | Sail La Vie

mei1970.org

 

[skunther]

This is how my magnets look after 9 months.

 

[skunther]

I am a big proponent of industrial velcro. One major reason is that it doesn't fail suddenly and it tends to self-heal. When it ultimately wears out, it is easily, inexpensively, and non-destructively replaced. I had a solar panel attached to a hard surface with velcro, years ago, and it was completely secure. The only real downside was that I had slide a little putty scraper or something in between the hook and loop surfaces to remove it because the grip was too strong to just pry the panel off.

As for 3M 4000, that's probably overkill. If you buy Velcro brand that is for outdoor use (I think it goes by a few names), the adhesive on that tape will definitely adhere to the panel. That isn't the problem. The problem is the canvas side. The adhesive on the tape would "probably" remain fixed to the canvas, but I would sew it on. My service dog's life vest has patches that are attached with velcro that adheres to the vest with just that adhesive. They endure quite a bit of abuse and hold fast, but I don't know that I would trust that to mount a solar panel - especially since it would be easy to just sew the velcro to the canvas.

I would have some concern over magnets interfering with the compass. Some people have an absolute rule about magnets on the boat, though I think this aversion is overemphasized.

One other half-thought is that you could mount the panels to another piece of canvas - just slightly larger than the panels themselves. Then, mount that canvas to the bimini using whatever you like - zipper, snaps, whatever.

I bought some industrial strength Velcro with adhesive backing with this in mind. The seamstress I’m using said she can sew the adhesive backed Velcro loop side to the canvas without any issue. I’d be concerned about needing to replace the Velcro and having to deal with the glue tho. Seems better just sewn and not glued.
I had also heard that the adhesive to the panel tends to fail after a couple years though, so that’s why I was thinking of using more robust adhesive there.
You haven’t had any issue with the adhesive on yours failing?

This is what I purchased:

 

[marcham]

I have had two 100 Watt panels secured with magnets (one in each corner) for 2 years now, none have ever come off. I use these magnets. One magnet gets bolted (stainless bolt) to the corner of the panel, the other goes under the canvas. Survived 60 mph wind storms.

Amazon.ca

Solar panels get hot, the glue won't last....

I'd avoid putting holes in the canvas or sewing anything.... if the panel fails, then you have to start all over again. The other advantage of the magnets is if you put the boat away for part of the season, it's easy to remove and stow them. The exposed velcro would have to be protected in that case.

 

[Foswick]

You haven’t had any issue with the adhesive on yours failing?
This is what I purchased:

Yeah, that's the stuff. I only had mine for about 3 years. It was in direct weather/sunlight pretty much continuously for that time, but showed no signs of failure. I have another application where I have equipment mounted to aluminum on a surface that has been outdoors for over 10 years, and the adhesive is still holding strong.

That said, I don't think there is anything wrong with overkill except that I don't know how an adhesive like 3M 4000 would interact with the already adhesive-coated surface. Might be just fine - I have no idea.

A nice thing is that, as I mentioned earlier, the attachment is somewhat self-healing. I had a sheet slip under a panel and rip it about 3/4 of the way off, but when the panel came back down, it immediately reattached like nothing happened. With a lot of other attachment methods, we would have lost the panel.

 

[skunther]

I do like the ease of panel replacement and adjustment with the magnets. It’s very clean. There’s also zero modification to the canvas, so if the configuration changes there won’t be any stitching or glue left on the canvas.They do seem to hold well enough in storms, as I’ve left mine on all winter with no issue in Squalicum Harbor.
Magnets are also super simple to install and don’t require any professional sewing of Velcro strips on the canvas.
I guess the only real concern with magnets is that they place the load on smaller contact hot points on the canvas. It seems over time that may damage and ultimately tear the fabric at the magnet footprint, more than hook and loop would. I wonder what the longest anyone has had magnet mounts on their solar panels is.

 

[thinwater]

I've had cheap semi-flex panels twice and gotten 12-15 years from them. However, they were not mounted on canvas. The problem with cheap panels on canvas is that the flexing causes micro-cracks in the cells, reducing output. It also speeds delamination. The silicon wafers are very fragile, and on semi-flex panels, we sacrifice the protection of glass and a frame.

If there is a trick, it is not how you attach them, it is how you keep them from flexing. Canvas is convenient, but it is a poor mounting surface. A rigid deck is much better.

 

[Foswick]

Thinwater makes a good point. I somehow missed that these are flexible panels. I think I would be tempted to preform them to the desired contour and layup fiberglass to keep them in that shape. Or, just accept that they will wear out, the more you flex them.

There is a lot more to this, though. A true thin-film (like amorphous silicon) panel isn't bothered by flexing and won't degrade in the same way a monocrystaline or polycrystaline flexible panel will. But, it is generally less efficient.

Kind of the only way to get longevity is to go with rigid (usually monocrystaline) panels, and don't damage them. My attitude about it, though, is that if flexible panel lasts 5-10 years and a rigid panel lasts 20-30, but I break it after 5 years, then what have I gained? (Though rigid panels are, on average, quite a bit more efficient.)

 

[skunther]

@marcham, have any of those magnets rusted, or does the epoxy keep them rust free?

I have had two 100 Watt panels secured with magnets (one in each corner) for 2 years now, none have ever come off. I use these magnets. One magnet gets bolted (stainless bolt) to the corner of the panel, the other goes under the canvas. Survived 60 mph wind storms.

Amazon.ca

Solar panels get hot, the glue won't last....

I'd avoid putting holes in the canvas or sewing anything.... if the panel fails, then you have to start all over again. The other advantage of the magnets is if you put the boat away for part of the season, it's easy to remove and stow them. The exposed velcro would have to be protected in that case.