Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
 
 


Reply
 
Thread Tools Display Modes
 
Old 06-24-2021, 07:42 PM   #1
Platinum Member
 
@Michael's Avatar
 
Join Date: Oct 2018
Location: MN
Posts: 367
Default Flexible Solar Panel mounting - Magnets?

I bought four neodymium magnets that come with a 6mm bolt & rubber coating and used them to hold down the four corners of a flexible solar panel. No adhesive, No holes in the roof. I'm spacing the panel off the roof with a bit of foam weatherstripping, partially for airflow, and partially to keep the panel from damaging the paint.

The magnets have about 26lbs force each. I could add a couple more or buy stronger ones if necessary.

Has anyone tried this before? Any reason why this won't work?

Should I run 'er up to a 'hunnerd and see if anything fly's off?







Attached Images
File Type: jpg PXL_20210610_144500738.jpg (322.8 KB, 249 views)
File Type: jpg PXL_20210610_144058871~3.jpg (214.5 KB, 242 views)
File Type: png magnet.png (156.7 KB, 203 views)
__________________

__________________
2019 Coachmen Crossfit
My Campervan Modifications and Travel Blog
@Michael is offline   Reply With Quote
Old 06-24-2021, 10:29 PM   #2
Platinum Member
 
GeorgeRa's Avatar
 
Join Date: Feb 2016
Location: Portland, Oregon
Posts: 2,793
Default

Quote:
Originally Posted by @Michael View Post
I bought four neodymium magnets that come with a 6mm bolt & rubber coating and used them to hold down the four corners of a flexible solar panel. No adhesive, No holes in the roof. I'm spacing the panel off the roof with a bit of foam weatherstripping, partially for airflow, and partially to keep the panel from damaging the paint.

The magnets have about 26lbs force each. I could add a couple more or buy stronger ones if necessary.

Has anyone tried this before? Any reason why this won't work?

Should I run 'er up to a 'hunnerd and see if anything fly's off?








Any shade could block harvesting, your AC blocks 6 cells, it could cause problems.
__________________

GeorgeRa is offline   Reply With Quote
Old 06-25-2021, 01:28 AM   #3
Platinum Member
 
@Michael's Avatar
 
Join Date: Oct 2018
Location: MN
Posts: 367
Default

Quote:
Originally Posted by GeorgeRa View Post
Any shade could block harvesting, your AC blocks 6 cells, it could cause problems.
Yep. But when this panel is shaded, the others are not - and vice versa. The way they are arranged, no matter where the sun is, I'll have two of three unshaded.
__________________
2019 Coachmen Crossfit
My Campervan Modifications and Travel Blog
@Michael is offline   Reply With Quote
Old 06-25-2021, 01:35 AM   #4
Platinum Member
 
GeorgeRa's Avatar
 
Join Date: Feb 2016
Location: Portland, Oregon
Posts: 2,793
Default

Quote:
Originally Posted by @Michael View Post
Yep. But when this panel is shaded, the others are not - and vice versa. The way they are arranged, no matter where the sun is, I'll have two of three unshaded.
Good strategy, with limited available space it is tough to eliminate shade. I assume panels are connected in parallel.

Good idea with magnets. You could add a strip of EPDM tape on the leading edges but I doubt it will be necessary.
GeorgeRa is offline   Reply With Quote
Old 06-25-2021, 03:31 AM   #5
Platinum Member
 
Davydd's Avatar
 
Join Date: Aug 2007
Location: Minnesota
Posts: 5,678
Default

There is a lot of forces on solar panels. I lost a flexible panel that was mechanically fastened down on the side rails. You probably need a faring on the lead panel which might impede low sun. I would think there will be more forces that those magnets can overcome.
__________________
Davydd
2021 Advanced RV 144 custom Sprinter
2015 Advanced RV Extended body Sprinter
2011 Great West Van Legend Sprinter
2005 Pleasure-way Plateau TS Sprinter
Davydd is offline   Reply With Quote
Old 06-25-2021, 05:58 AM   #6
Platinum Member
 
GeorgeRa's Avatar
 
Join Date: Feb 2016
Location: Portland, Oregon
Posts: 2,793
Default

Quote:
Originally Posted by Davydd View Post
There is a lot of forces on solar panels. I lost a flexible panel that was mechanically fastened down on the side rails. You probably need a faring on the lead panel which might impede low sun. I would think there will be more forces that those magnets can overcome.
Was it a panel spanning across the roof attached to roof rail, there could be a lot of panel oscillation and lifting. But, I agree, there is some risk.

Sealing a front panels gaps would likely solve a problem.

My preference is rigid panel with rigid mounts.
Attached Images
File Type: jpg ZGR01032.jpg (706.1 KB, 16 views)
GeorgeRa is offline   Reply With Quote
Old 06-25-2021, 10:56 AM   #7
Platinum Member
 
markopolo's Avatar
 
Join Date: Oct 2006
Location: New Brunswick, Canada
Posts: 8,823
Default

If lower on the vehicle I'd expect you'd see iron debris accumulating and rusting. Roof might be different, you'll have to report back on that to let us know. Also, I have some plated neodymium magnets that rusted pretty quickly so hopefully your rubber coated ones will fair better.
__________________
Two bikes on sliding cargo box: https://www.classbforum.com/forums/m...icture206.html & 1997 GMC Savana 6.5L Turbo Diesel Custom Camper Van Specifications: https://www.classbforum.com/forums/f...vana-5864.html
markopolo is offline   Reply With Quote
Old 06-25-2021, 12:41 PM   #8
Platinum Member
 
Davydd's Avatar
 
Join Date: Aug 2007
Location: Minnesota
Posts: 5,678
Default

Exterior magnets attract a lot of iron debris. We had magnet closures in our last van for the nerf bar storage that Advanced RV later eliminated. They don’t use any magnets now on the exterior but we have a lot of magnets inside the van mostly for hanging curtains and night closer curtains and the bathroom door stays open if there is any unlevelness that could cause it to swing back.
__________________
Davydd
2021 Advanced RV 144 custom Sprinter
2015 Advanced RV Extended body Sprinter
2011 Great West Van Legend Sprinter
2005 Pleasure-way Plateau TS Sprinter
Davydd is offline   Reply With Quote
Old 06-25-2021, 01:26 PM   #9
Site Team
 
avanti's Avatar
 
Join Date: Jul 2013
Posts: 4,892
Default

Anyone who has ever carried a mattress on their car's roof at speed understands how easy it is to build an airfoil with very powerful lift. IMO, using magnets for this purpose is asking for trouble. If you don't want to drill holes, 3M VHB adhesive tapes (the strong ones) will do the job, if properly installed.
__________________
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
Now: 2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
Next: 2022 Fully-custom buildout (Ford Transit EcoBoost AWD)
avanti is offline   Reply With Quote
Old 06-25-2021, 02:37 PM   #10
Platinum Member
 
Join Date: Nov 2014
Location: PHX, AZ
Posts: 2,308
Default

I like magnets , but that thing needs a mechanical fixture to keep it from killing the guy behind you.


"it's only air"




yes air:


mkguitar is offline   Reply With Quote
Old 06-25-2021, 02:57 PM   #11
Platinum Member
 
Join Date: Aug 2010
Location: Minnesota
Posts: 10,687
Default

Wind forces are huge in some cases, think wings a spoilers on vehicles to hold them down as the driving wind can severely reduce the weight on the tires and make the car float.


Static force is bad, but conditions can also make flexible stuff flutter and that is way, way, worse for making things break or come off.



Personally, I wouldn't consider that setup safe and as Avanti mentioned, if it comes off and causes an accident lots of bad things could happen.
booster is offline   Reply With Quote
Old 06-25-2021, 03:35 PM   #12
Platinum Member
 
Join Date: Nov 2014
Location: PHX, AZ
Posts: 2,308
Default

mounting panels on the roof requires you park in the sun.


consider carrying your panels inside the vehicle


parking in a shady spot


and then setting up your panels where the sun is better, moving them to take best advantage through the day



you just need 20' of wire


mike
mkguitar is offline   Reply With Quote
Old 06-25-2021, 05:44 PM   #13
Platinum Member
 
@Michael's Avatar
 
Join Date: Oct 2018
Location: MN
Posts: 367
Default

Quote:
Originally Posted by avanti View Post
3M VHB adhesive tapes (the strong ones) will do the job, if properly installed.
VHB is an option, but VHB has a disadvantage of being really hard to remove and clean off the roof when I need to replace the panel. I already have two factory panels that are held down with some kind of adhesive (Sika 221 or Manus-bond??), which seems to be impossible to peel off the roof without damage.

Quote:
Originally Posted by booster View Post
Wind forces are huge in some cases, think wings a spoilers on vehicles to hold them down as the driving wind can severely reduce the weight on the tires and make the car float.

Static force is bad, but conditions can also make flexible stuff flutter and that is way, way, worse for making things break or come off.
I hear you. The question is 'how much is enough' when it comes to resisting the dynamic forces from wind under the panel.

It seems like a few square inches of VHB will hold a rigid panel in place. I.E AMSolar says two 1" x 5" strips of VHB are enough to hold a rigid panel in place. This implies that 10 sq. in. of VHB at 22lbs/sq. in. peel adhesion strength is enough.

Quote:
Originally Posted by mkguitar View Post
consider carrying your panels inside the vehicle
... and then setting up your panels where the sun is better, moving them to take best advantage through the day
Been there. Done that. Storing 2' x 4' panels inside the van is a genuine PITA, and the portable panels are only useful when one is sitting in one spot & can leave them unattended without worrying about theft or damage.

The fold-up panels store easier, but are more expensive less inefficient.
__________________
2019 Coachmen Crossfit
My Campervan Modifications and Travel Blog
@Michael is offline   Reply With Quote
Old 06-25-2021, 06:18 PM   #14
Bud
Platinum Member
 
Join Date: May 2016
Location: LA
Posts: 1,472
Default

Quote:
Originally Posted by @Michael View Post
VHB is an option, but VHB has a disadvantage of being really hard to remove and clean off the roof when I need to replace the panel. I already have two factory panels that are held down with some kind of adhesive (Sika 221 or Manus-bond??), which seems to be impossible to peel off the roof without damage.



I hear you. The question is 'how much is enough' when it comes to resisting the dynamic forces from wind under the panel.

It seems like a few square inches of VHB will hold a rigid panel in place. I.E AMSolar says two 1" x 5" strips of VHB are enough to hold a rigid panel in place. This implies that 10 sq. in. of VHB at 22lbs/sq. in. peel adhesion strength is enough.



Been there. Done that. Storing 2' x 4' panels inside the van is a genuine PITA, and the portable panels are only useful when one is sitting in one spot & can leave them unattended without worrying about theft or damage.

The fold-up panels store easier, but are more expensive less inefficient.

Very Interesting Michael, would also be interesting to 'see' what's happening up there with a video camera?

I'm not placing any bets yet, but I'm going with just maybe you're ok. Problem is without a camera, maybe not a good bet to make. But heck if I know.

Fun project though. Have fun.

Bud
Bud is offline   Reply With Quote
Old 06-25-2021, 07:10 PM   #15
Platinum Member
 
GeorgeRa's Avatar
 
Join Date: Feb 2016
Location: Portland, Oregon
Posts: 2,793
Default

Quote:
Originally Posted by @Michael View Post
VHB is an option, but VHB has a disadvantage of being really hard to remove and clean off the roof when I need to replace the panel. I already have two factory panels that are held down with some kind of adhesive (Sika 221 or Manus-bond??), which seems to be impossible to peel off the roof without damage.
..
VHB uses acrylic adhesives vs Sika 221 (or 3M 4XXX or 5XXX) which is polyurethane. VHB, once separated, can be removed with solvents like WD40 or GooGone. Polyurethane can be removed with Aqua Regia, unfortunately it would make a hole in the roof. Best way to cut through polyurethane is a piano wire, for example windshields replacements.

Sealing the leading-edge gap between the solar panel on the roof would prevent potentially harmful harmonic oscillation. Butyl tape could be used, it stays flexible and can easily be removed.
GeorgeRa is offline   Reply With Quote
Old 06-25-2021, 07:24 PM   #16
Platinum Member
 
Join Date: Aug 2010
Location: Minnesota
Posts: 10,687
Default

I think tight to the roof and sealed front edge is totally different than standing proud on the magnets. You still get the upward pull on the panel is tight down and retained on edges, though, depending on roof shape and attack angle of the wind to the roof. Of course the right roof shape could help hold it down also.


The roof of our Chevy Roadtrek slopes down to the rear and is crowned a bit side to side, so our rigid panels are mounted stair step style on angled mounts, with the panel orientation carefully matched to be parallel to the ground to minimize lift or push down on them. I intentionally did not seal the front edge except for the no choice area where the air is blocked by the ceiling vent fan cover as that in itself will create more air pressure on the panels. We have had no issues with it affecting the van handling or with looseness, but our brackets are on with rivet nuts with bolts and urethane caulking/adhesive so very secure. The crown on the roof makes the thicker, stronger, adhesive necessary. Tape would only contact about 20% of our bracket area in this case unless the brackets were bent to exactly the same curvature.
booster is offline   Reply With Quote
Old 06-25-2021, 08:06 PM   #17
Platinum Member
 
GeorgeRa's Avatar
 
Join Date: Feb 2016
Location: Portland, Oregon
Posts: 2,793
Default

Quote:
Originally Posted by booster View Post
I think tight to the roof and sealed front edge is totally different than standing proud on the magnets. You still get the upward pull on the panel is tight down and retained on edges, though, depending on roof shape and attack angle of the wind to the roof. Of course the right roof shape could help hold it down also.


The roof of our Chevy Roadtrek slopes down to the rear and is crowned a bit side to side, so our rigid panels are mounted stair step style on angled mounts, with the panel orientation carefully matched to be parallel to the ground to minimize lift or push down on them. I intentionally did not seal the front edge except for the no choice area where the air is blocked by the ceiling vent fan cover as that in itself will create more air pressure on the panels. We have had no issues with it affecting the van handling or with looseness, but our brackets are on with rivet nuts with bolts and urethane caulking/adhesive so very secure. The crown on the roof makes the thicker, stronger, adhesive necessary. Tape would only contact about 20% of our bracket area in this case unless the brackets were bent to exactly the same curvature.
I think, if the front gap between the panel and the roof is completely sealed with a butyl tape as thick as rubber magnets it will prevent front edge from oscillation and variable vortex. A 3-4 inches wide butyl tape could form a wind deflector as well. There still going to be some lift on the panel but likely insufficient to rip the panel off the roof.

I still prefer rigid panels:
1. No issue with potential flying frisbees
2. Air gap will allow cooling airflow under panels
3. A "Double Roof" will keep van cooler in sunny days.
GeorgeRa is offline   Reply With Quote
Old 06-25-2021, 09:06 PM   #18
Platinum Member
 
@Michael's Avatar
 
Join Date: Oct 2018
Location: MN
Posts: 367
Default

Quote:
Originally Posted by GeorgeRa View Post
VHB uses acrylic adhesives vs Sika 221 (or 3M 4XXX or 5XXX) which is polyurethane. VHB, once separated, can be removed with solvents like WD40 or GooGone. Polyurethane can be removed with Aqua Regia, unfortunately it would make a hole in the roof. Best way to cut through polyurethane is a piano wire, for example windshields replacements.

Sealing the leading-edge gap between the solar panel on the roof would prevent potentially harmful harmonic oscillation. Butyl tape could be used, it stays flexible and can easily be removed.
Good info. Thanks.

Quote:
Originally Posted by GeorgeRa View Post
I think, if the front gap between the panel and the roof is completely sealed with a butyl tape as thick as rubber magnets it will prevent front edge from oscillation and variable vortex.
That would be easy to do.

Quote:
Originally Posted by Bud View Post
Very Interesting Michael, would also be interesting to 'see' what's happening up there with a video camera?
Good idea. A perfect excuse to buy a GoPro.
__________________
2019 Coachmen Crossfit
My Campervan Modifications and Travel Blog
@Michael is offline   Reply With Quote
Old 06-26-2021, 12:10 PM   #19
Platinum Member
 
markopolo's Avatar
 
Join Date: Oct 2006
Location: New Brunswick, Canada
Posts: 8,823
Default

Quote:
Originally Posted by booster View Post
................if it comes off and causes an accident lots of bad things could happen..........
Yes, really bad such as this: ( https://www.abc.net.au/news/2020-10-...-ross/12726538 )



Quote:
Police believe the crash occurred after a southbound vehicle, a red Toyota Celica, lost control after trying to avoid hitting a solar panel that dislodged from a caravan, then colliding with a northbound vehicle.
The driver of the southbound vehicle, a 48-year-old man from Launceston, his 15-year-old daughter and 71-year-old aunt died at the scene.
Here's a video of a non-related incident that gives an idea of what any of us might encounter at any time when following an RV.

__________________
Two bikes on sliding cargo box: https://www.classbforum.com/forums/m...icture206.html & 1997 GMC Savana 6.5L Turbo Diesel Custom Camper Van Specifications: https://www.classbforum.com/forums/f...vana-5864.html
markopolo is offline   Reply With Quote
Old 06-26-2021, 03:42 PM   #20
Platinum Member
 
Boxster1971's Avatar
 
Join Date: Mar 2012
Location: Maryland
Posts: 1,124
Default

My only thought - Yikes!!
__________________

__________________
2013 Airstream Interstate Lounge EXT on 2012 Sprinter 3500 170Ext
Formerly: 1973 Dodge B300 DIY pop-top conversion
Boxster1971 is offline   Reply With Quote
Reply

Tags
solar

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 06:33 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
×