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Old 06-24-2016, 10:36 PM   #1
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Default Attaching Solar Panel(s) Coachmen Class B

Hello Folks,

I am getting ready to proceed with the solar panel installation on my 89 Coachem Class B. Quick Question for anyone who may have done this: What size/Length Screws did you use to actually attach the brackets to the fiberglass roof of the RV? I want to avoid punching down through the headliner

thanks
-t
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Old 06-24-2016, 11:40 PM   #2
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.

If your roof is aluminum or fibreglass, you don't have to drill.

You can use adhesive to glue the mounting brackets to your roof.

Today's adhesives are stronger than weld !!!

You can also check out 3M VHB tape.


If your roof is rubber, then you have to use screw. Adhesive will not work.
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Old 06-25-2016, 12:04 AM   #3
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Here's a link to a VHB tape failure: http://www.classbforum.com/forums/f2....html#post8728

A while back I searched the web and found reports of other failures. No doubt there are success stories also. I just encourage folks to think about the potential consequences if something like a large solar panel flies off the roof & hits another vehicle or person.
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Old 06-25-2016, 01:34 AM   #4
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Quote:
Originally Posted by markopolo View Post
Here's a link to a VHB tape failure: http://www.classbforum.com/forums/f2....html#post8728

A while back I searched the web and found reports of other failures. No doubt there are success stories also. I just encourage folks to think about the potential consequences if something like a large solar panel flies off the roof & hits another vehicle or person.
Quote:

...the FAILURE was that the metal "footings" where attached to a PAINTED
surface versus fiberglass.
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Old 06-25-2016, 01:41 AM   #5
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.

There are 3 key factors for successful adhesives:

1. good surface prep -- the bonding area must be bondable

2. sufficient surface area for the adhesive -- you must calculate the amount of gluing surface area needed to provide sufficient bond for the required load.

3. proper mounting hardware -- you can't just glue the Z-bracket. Although I have seen people do it. But you should use proper ABS mounting hardware.

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Old 06-25-2016, 02:18 AM   #6
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There are very, very, many different things to worry about when using just adhesive, be it tape or liquid/caulk. The shape of the pieces being bonded have to match within the the adaptability of the adhesive, and I would consider this the concern that is most likely to bite someone. Many/most class B roofs are sloped, or even compound curved, so it is very hard on many of them to accurately determine if the foot and roof are parallel enough for tape. If you won't stick it to paint, you leave out nearly all the new units, but many of the solar folks say it is OK, so that is another choice. Of course there is factory paint and aftermarket differences also. Oxidized gelcoat, especially if it has been waxed or treated with any silicone based "reconditioner" may have worse adhesion than paint. You also need to protect the edge of the tape, if you use tape, from UV as it will deteriorate.

This is not to say adhesive won't work, as there are many documented cases where it did, but there are also documented cases where it didn't. Personal choice, and risk aversion.

For me, when I did ours on our painted, curved, fiberglass Roadtrek roof, I chose to use rivnuts (steel) and then use urethane adhesive caulk to seal and be the primary adhesive. Using the caulk allows 100% compliance with curves so much better than tape in this application. If the caulk fails, the rivnuts will keep the panel from killing anyone. I like a bit of redundancy in areas that could be hazardous in a failure. With the caulk 100% sealing all around the rivnut, and the screw into it, the chance of a leak are extremely small, and the time to do it is not bad at all, so for me there was not really any downside of consequence.
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Old 06-25-2016, 12:12 PM   #7
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Even if you use adhesives to mount, how are you going to bring the wires into the coach, without punching any holes? I think there is no way getting around it. Just punch the needed holes and use a lap sealant.
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Old 07-22-2016, 12:15 PM   #8
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The whole roof worth of solar panels (640w) held down by 6 pieces of VHB tape.

The Building of BoB the Van - Page 3 - Ram Promaster Forum




ps. not my build
not endorsing nor criticising his mounting method
just a data point
YMMV
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Old 07-22-2016, 02:39 PM   #9
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Quote:
Originally Posted by BBQ View Post
.................................................. ..... ps. not my build
not endorsing nor criticising his mounting method
just a data point
Good points - it's all about getting good info out there for people to read.

Two people made the effort to contact AM Solar and were advised to use screws (in addition to VHB tape): Solar panel blown away! - Page 5 - Airstream Forums

I see people recommending Dicor a lot on Class B groups. I like Dicor & use it but it's not recommended for painted surfaces as far as I know. I've used it on painted surfaces with the knowledge that it's likely not the best option.

Quote:
Compatible with EPDM and TPO sheeting, it adheres firmly to aluminum, mortar, wood, vinyl, galvanized metal, fiberglass and concrete.
Stuff just seems to get repeated so often that it seems to become fact when in reality it's probably not.

It's interesting to see how cleanly the solar panel foot "pops" off in this video:



Edit: forgot to add isopropyl alcohol shouldn't have much affect according to 3M - http://multimedia.3m.com/mws/media/7...oduct-info.pdf

Quote:
Testing has revealed no apparent degradation of any VHB Tape when exposed to splash testing of most common solvents, including water, petrol, white spirits, motor oil, ammonia cleaner, acetone, methyl ethyl ketone (MEK) and isopropyl alcohol.
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Old 07-22-2016, 03:12 PM   #10
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Default Sticking the Panel to the Roof

Sticking the Panel to the Roof using VHB tape

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