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Old 30-11-2020, 07:45   #1
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Use Strong Magnets to Mount Flexible Solar to Bimini??

Good Day! We are considering using strong rare earth magnets to mount flexible solar panels to our bimini. We will use Reflectix between the Sunbrella and the panels to keep the heat down and protect the canvas. This will be a temporary mount until proper zippers or Velcro can be sewn in later, or perhaps we will just stick with the magnets if they work well.


Any experience out there using rare earth magnets for flexible solar? Thanks!
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Old 30-11-2020, 08:05   #2
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

Greetings and belated welcome aboard the CF, TJ.
How will you maintain the required air space, between the Reflectix radiant barrier, and the underside of the PV panels?
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Old 30-11-2020, 10:59   #3
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

Thank you for your input Gord May. I have read several hundred of your posts and really value your opinion. Good point on the air space. I see a lot of flexible solar panels on other boats that appear to be sitting directly on the canvas. I assume this is incorrect? I figured sandwiching Reflectix between the canvas and the panels would be an improvement, but perhaps this still will not provide enough of an air gap. From there, I am considering using six pairs of 100lb pull strength magnets per panel, after coating the magnets in epoxy paint or Plasti Dip to delay rust. I just won't have the ability to properly sew Velcro flaps into the bimini for some type, so was hoping magnets might be a short-term solution.
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Old 30-11-2020, 11:34   #4
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

bimini covers are used over boat cockpits, from which most boat maneuvering is conducted. I understand we live in a digital geo-location GPS world now, but the binnacle compass would probably be right below your collection of strong magnets. The first rule of boating is safe operations - a working magnetic compass enhances safety in many mission critical operations.
Why dont you try bungie cords or cable ties to hold down your solar panels?
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Old 30-11-2020, 14:39   #5
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

I'm feeling particularly dense this morning, but just what are these magnets sticking too in your proposed design? Could you either sketch or describe this in more detail, please?

Jim
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Old 30-11-2020, 15:15   #6
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

Hello Jim. The magnets will be sticking to themselves. Imagine about six 100lb pull strength magnets (about 1.5 inches wide) on each panel, and another six magnets on the underside of bimini, with the North and South sides of the magnets attracting each other and hopefully keeping the panels secure!
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Old 30-11-2020, 15:30   #7
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

^^^^^

Ahh, so! Thanks for the fill-in. I now understand your idea, but can't offer any meaningful advice. I velcroed a 100 watt semi-flex panel to our cloth dodger and it damn near came off in only about 40 knots. I had to physically hold it down in the gusts. Later I modified the velcro arrangement to be quite a lot stronger and it worked ok (the panel didn't, though... the vibration from wind forces caused an early failure).

So, don't underestimate the lift that strong winds can exert on the panels. I don't have a clue how strong your magnetic hold down would be.

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Old 30-11-2020, 18:52   #8
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

I would not bother taking a short cut like that: Magnets..

When I mounted solar panels over the bimini some 16 years ago, 1 inch stainless steel archs were used, so was a lot of other hardware and the panels stayed on during hurricane Wilma, she came overhead pushing 105 knot winds gusting 120 knot.
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Old 01-12-2020, 09:35   #9
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

As AndyEss said - what about your compass?? Your chartplotter & autopilot will work off a fluxgate compass tucked away safely (hopefully) down below somewhere - but your (main, last resort when all else fails) cockpit compass needs to be at least a metre away from anything metal (like an engine) & sticking powerful magnets within a couple of metres (just over 6 feet) of the compass is not a good idea...
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Old 01-12-2020, 09:50   #10
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

Isn't your Bimini frame made out of Stainless Steel. If so magnets won' or at least shouldn't work. JMHO
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Old 01-12-2020, 10:20   #11
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

If you use the magnets to attach your flexible solar system, get underway and box the compass with at least 8 courses (N, NE, E, SE, etc.) and compare your magnetic compass readings to GPS. If the mag. compass is affected, there is probably no way to adjust it.
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Old 01-12-2020, 10:28   #12
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

Did you remove the bimini ? Do you have to remove the panels to remove the bimini. I took down both for irma. What a pain.
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Old 01-12-2020, 11:01   #13
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

Ive seen other posts of folks doin what you are proposing. Hopefully someone with some actual experience with magnet anchors will weigh in. Otherwise you may need to do some further searching in this and other sites.

Ive considered magnets an option as I only plan to put up the panels when at anchor. My weather is more predictable and not subject to sudden summer squalls. That said, theyd be tucked under a mattress and not subject to sunlight and degradation for the days shes sailing locally or sitting in her slip. Your uses and needs may be quite different.

Also - as another option, my canvas installer showed me some pictures where solar installations used small screws and barrel nuts going through the fabric using SS washers over large nylon washers to spread out the load on the fabric. They used a carefully inserted awl to spread apart and not tear the fibers during installation. So far this system has reportedly been sound and without issues over several years. Just another option dependent on your usage and environmental factors.
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Old 01-12-2020, 11:51   #14
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

The corrosion resistance of rare earth magnets is poor. So if you go the magnet route, corrosion protection of them is important.
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Old 01-12-2020, 12:03   #15
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Re: Use Strong Magnets to Mount Flexible Solar to Bimini??

My experience with magnet hold-downs in similar situations suggests that they're not very good at preventing slip-sliding sideways creeping movement over time. A combination of velcro and the magnets would prevent that.

I'm not recommending magnets for your use just suggesting other factor to consider.
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