Airstreamer looking for some advice on mounting to a curved roof

Stepandwolf

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Probably is 2" X 2". The first roll I used for installation was a 4" Eternabond Roof tape. That ran out and I started to use Dicor Roof tape I picked up off the shelf at a local Camping World. I Do cut the roofing tape into a square so its a bit bigger than the mount and will secure it. Got the method from this guy at 2:45 in


The PV wire I use is 10 AWG on the roof. That is here: https://www.wireandcableyourway.com/solar-photovoltaic-pv-wire. There is some 6 AWG wire in the area, but I don't think it made the pick.

Even though the PV wire was UV rated, to make the installation look better, I bought 100' of white split loom wire off E-Bay at this place: https://www.ebay.com/itm/131571481083. Could be that because the split loom is not UV resistant, I may need to replace in a few months. I may just take a split loom and paint it white.
I found a company, Electriduct that makes a UV resistant wire loom tubing but only in black. They make white tubing, but not UV resistant. Compared to having red and black cables on the roof, a black wire loom isn't horrible. I don't know many people who are 10' tall and will see it :)


Seems the 1/2" OD (.47 ID) should be large enough for a pair of PV cables. Do you remember the diameter of your tubing?

I bought one of those 20' extension OV cables I hope is long enough.
 

chrisski

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. I hope this addresses some of the valid concerns with this install method.
I don’t think it addresses any concerns. You got the install method from a professional shop that uses hardware like rivets to secure the panels, and skipped that step.
 

chrisski

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Do you remember the diameter of your tubing?
I got 3/8” White. I can‘t remember if there was more than one wire in it or not. I probably only put one. Not that maby places up there two wires come together.
 

Wattson

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I don’t think it addresses any concerns. You got the install method from a professional shop that uses hardware like rivets to secure the panels, and skipped that step.
I have to ask, did you even watch any of the information I presented? In the AM Solar video please give me a time stamp that corresponds to them using fasteners to attach the solar panels (other than the VHB tape).

Thanks in advance.
 

Stepandwolf

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I got 3/8” White. I can‘t remember if there was more than one wire in it or not. I probably only put one. Not that maby places up there two wires come together.
My panels will be in a row along the edge of the roof and all interconnections will be done with tiewraps under the rack they will be mounted to. I was only asking about the best way to get from there across the roof, and that would be two wires, i.e. positive and negative. Don't know where you would be running a single wire?
 

chrisski

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I have to ask, did you even watch any of the information I presented?
I did not watch the install video. No YouTube video could convince me that any tape, glue, or epoxy alone is a good idea for installing a flat panel on a roof.

At this point we’re just repeating ourselves.
 

chrisski

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Don't know where you would be running a single wire?
Not really a single wire. More like By the time the positive and negative wire hooked back up, they were a couple feet from the Entry box. This is a pic of the entry box before the VHB tape was added.492C9A76-0964-4399-AB89-E17719C565BB.jpeg
THose peel and stick brackets did not last long before coming off, weeks at best.
 

Stepandwolf

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Not really a single wire. More like By the time the positive and negative wire hooked back up, they were a couple feet from the Entry box. This is a pic of the entry box before the VHB tape was added.
THose peel and stick brackets did not last long before coming off, weeks at best.
Seems the best way to route from my roof to the intended battery location is going down through a closet on the left front of the trailer. When I install the second set of panels, they will be over that location, but I am installing the panels down the right side of the roof, so I will need to turn the pair of wires from the right front to the left front, 6 or so feet across the roof to the junction box. I won't have a combiner as I am not combining anything. the 3S2P config will be a single pair of wires. When I install the second set of panels, they will come down through the same box to it's own MPPT in the battery area. With my intended installation method, the only cable you will see (after installing second set of panels) is about two feet of cable between the two sets of panel. I added the box in the left front under the first panel and the purple line runs under that panel, across the roof and then under the panels on the right side of the roof. For now, I am only installing the six panels on the right side of the roof so the cable from the inside edge of the solar panel to the pass-through box is all that will be visible, and when the second set of 6 panels are installed, only that middle piece of cable will be visible.

I am considering running a plate across the leading edge of the panels angled to match the trailer nose to both deflect the wind plus give something for objects to hit instead of the panel. If I install that "air foil" across the front, the cable can route there instead.
trailer roof5.jpg
 

12VoltInstalls

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peel and stick brackets did not last long before coming off
Not surprised.
The very nice 3M tape that I’ve used for other things in the past and am convinced of its high quality is what came with my $40 glass mount I started using for an old iPhone4.
I implemented it for hosting the speed55 “black box recorder” in my jeep (after getting a completely bogus traffic ticket - that cost me a lot of money- that I couldn’t prove I didn’t commit but that’s another story).

It lasted maybe 3 days before it got hot in the sun (at 35*F outside) and fell off. Weight/force/heat notta do workie with that stuff!- It’ll hold stuff in place but it won’t hold force with vector and temperature.

I might trust epoxy?! but no, actually I’d want a mechanical connection if safety was part of the question.
 

McCarthy

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2 aluminum strut channels, connected to the roof with 14 screws into 1/2" Rivnuts. For ONE 465 watt panel.

That's how you install solar panels properly on a roof.




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Stepandwolf

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2 aluminum strut channels, connected to the roof with 14 screws into 1/2" Rivnuts. For ONE 465 watt panel.

That's how you install solar panels properly on a roof.




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When working with a trailer/motorhome roof, there are trusses to bolt into. I think you were overboard on your install. I am making a rack out of 1.5" square aluminum which will be attached to the trusses and the panels will attach to the square. Instead of four holes in the roof at random places per panel, I will be putting less holes in but I don't think my rack will pull off of the roof in the wind. I expect to only have 12-14 holes in the roof for the rack to hold six panels.
 

McCarthy

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When working with a trailer/motorhome roof, there are trusses to bolt into. I think you were overboard on your install. I am making a rack out of 1.5" square aluminum which will be attached to the trusses and the panels will attach to the square. Instead of four holes in the roof at random places per panel, I will be putting less holes in but I don't think my rack will pull off of the roof in the wind. I expect to only have 12-14 holes in the roof for the rack to hold six panels.

There is much more to all this. Just a disclaimer at this point, I used to work for Mercedes Benz in R&D, in Germany, Bremen to be exact. We did - among other things - crash testing.

Now, what do you think will happen with any of those half-assed-installed solar panels if you rear-end somebody? What's going to happen with that momentum in the panels? Any idea what forces will remain in that 40 pound panel when the vehicle comes to a stop from 50 to 0 MPH in just a few feet?

They come flying off, right into the direction of that innocent person you just hit or any bystanders.

In Germany EVERY part that gets installed on a vehicle, OEM or aftermarket, needs to be testes for safety by the TUV, and gets certified by an ABE (Allgemeine Betriebserlaubnis = general operating permit). If you would get caught in Germany with any rack that was not certified, you will face a fine, you will not be allowed to operate that vehicle anymore, and if that part causes a crash or harm to anybody, the insurance will not cover you, and you will be liable for any outcome. For a good reason.

Did any of you do any crash tests to make sure it will not take somebody's head off?

If you would try to get a certification with a rack attached with tape, in Germany, you would not only fail but pay for that failed attempt.

Be glad that we have less regulations in the US, BUT if we do stupid things and people get hurt, we all will face the same onslaught of regulations because a few worry more about putting holes into their holy grail airstream roof than the safety of people when those panels come off with wind or in a crash.

I think I made my point clear in this thread and leave it at that.

If 'your' solar panel installation causes any harm to any bystanders, you will remember my posts.


 
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Stepandwolf

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There is much more to all this. Just a disclaimer at this point, I used to work for Mercedes Benz in R&D, in Germany, Bremen to be exact. We did - among other things - crash testing.

Now, what do you think will happen with any of those half-assed-installed solar panels if you rear-end somebody? What's going to happen with that momentum in the panels? Any idea what forces will remain in that 40 pound panel when the vehicle comes to a stop from 50 to 0 MPH in just a few feet?

They come flying off, right into the direction of that innocent person you just hit or any bystanders.

In Germany EVERY part that gets installed on a vehicle, OEM or aftermarket, needs to be testes for safety by the TUV, and gets certified by an ABE (Allgemeine Betriebserlaubnis = general operating permit). If you would get caught in Germany with any rack that was not certified, you will face a fine, you will not be allowed to operate that vehicle anymore, and if that part causes a crash or harm to anybody, the insurance will not cover you, and you will be liable for any outcome. For a good reason.

Did any of you do any crash tests to make sure it will not take somebody's head off?

If you would try to get a certification with a rack attached with tape, in Germany, you would not only fail but pay for that failed attempt.

Be glad that we have less regulations in the US, BUT if we do stupid things and people get hurt, we all will face the same onslaught of regulations because a few worry more about putting holes into their holy grail airstream roof than the safety of people when those panels come off with wind or in a crash.

I think I made my point clear in this thread and leave it at that.

If 'your' solar panel installation causes any harm to any bystanders, you will remember my posts.


Generally an accident involving pedestrians is low speed and wouldn't cause even poorly installed panels to come off. Even if a vehiicle accident in a crowded pedestrian area, I just don't think inertia would exist. In high speed crashes the panels are probably the least of the worries as the vehicles colliding will be the problem. Can something horrible happen, sure, but the odds are beyond speculation.
 

PerryB67

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I have to ask, did you even watch any of the information I presented? In the AM Solar video please give me a time stamp that corresponds to them using fasteners to attach the solar panels (other than the VHB tape).

Thanks in advance.
You can lead a horse to water, but . . . . . .
 

PerryB67

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Looking at the videos that McCarthy posted it's apparent people just don't understand physics.

Video #1 shows a large panel mounted in front of the air conditioning probably at the front of the camper at an angle. GoPower does not want their panels mounted within three feet of the front of the camper. The initial angle with the 5th wheel scoops the air underneath the panel and off it goes. The mistake was mounting the panel too close to where the front scooped air exists. It also appears to have taken some gelcoat with it. Another question, was the roof properly prepared for the VHB tape?

Video #2 shows a large panel with mounts too small/thin to remain stiff. Vibration will cause the mounts to fail. Spend the money and time on strong mounting hardware.

Video #3 the guy mounted three panels together making a huge sail, with mounts only at the edges. Even he figured out that style of mounting was the problem. How many square inches is your sail? Mount every panel separately!

Video #4 shows that he mounted his rear panel with inadequate tape (what kind?) and thin mounts at the edge of the roof. He mounted the panel at the angle where it goes from horizontal to vertical. You can't fix stupid!

Video #5 just shows a portable that was mounted on their roof. Since it didn't happen going down the road I don't know why this one was included.

AM solar uses only four mounts with VHB tape on a large panel held with only 4 mounts. They only use 2 1/2 square inches per mount for only 10 square inches total. I seriously doubt they've never had a panel blow off.

Using the Rich Solar 200 watt panel (58.7" x 26.8") there is 1573 square inches of sail that AM solar would hold on the roof with 10 sq in's of VHB tape. Not enough for me, but with larger panels I'd use six brackets no matter how they are attached. We chose three Renogy 100 watt panels (42 x 20) with 840 sq in's of sail, about 53% of sail vs that Rich Solar panel.

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Our front panel behind the escape hatch has 6" x 2" front brackets on each side and 7 1/2" X 2" brackets on the back. That's 54 square inches of VHB tape holding the panel that gets the most wind in place. The escape hatch is 24" so only 18" is really exposed to the frontal air. 54 square inches of tape is total overkill!

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The center panel behind the front panel, but ahead of the Maxx Fan has 7 1/2" x 2" brackets on the front and 4" x 2" brackets holding the rear. That's 46 square inches holding the panel in place. More overkill!

The rear panel between the air conditioning and Maxx Fan has 3 1/2" x 1 1/2" brackets on all four corners. That's 21 square inches holding that panel protected by the Maxx Fan and the two forward panels. Still overkill.

Remember AM Solar uses just 10 square inches total to hold a considerably larger panel. I think our panels are safe with three to five times the amount of VHB tape, but we're using the correct VHB tape and properly preparing our fiberglass. I've done my homework.

Yes our panels are cabled so if one does fail it will just wreck our roof, just in case I'm human.

I could link to some recent threads here where you see cheap flexible mounts that will fail, but I'm sure you know which I'm talking about.

I also do agree that most taped panels are using too little tape, mounted in the wrong spot, on the wrong roof (rubber, etc.), and have not had the roof properly prepared. Again, do your homework!

If you wish to understand my reasoning for the install read Adding 300 Watts Solar To Our 5.0 on the Escape forum.

Enjoy,

Perry
 
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PerryB67

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If it took gel coat I’d say, “yes!”

Mechanical fasteners? Yup, good idea.
Actually neither of us knows which went first, the inadequately prepared roof/mount or the gel coat. My guess is the one with the gel coat was the only one that was prepared properly, but with the other three failing the gel coat was overleveraged.

Many mechanical fasteners have failed on campers as well.

It comes down to proper design and installation.

Enjoy,

Perry
 

McCarthy

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Had a hard time finding a datasheet on the VHB tapes, the US 3M website has a dead link. All they show is marketing crap and "For industrial/occupational use only. Not for consumer sale or use.". Awesome liability jargon.

Found this on the 3M UK website. Check out this crazy drop in tensile adhesion once it gets to only 50 F. The tape will face 170 F easily on a sunny summer day, on the roof of a trailer or RV. Meanwhile its down to 10% strength.




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jwelter99

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Either install panels properly; with the correct mechanical fasteners; or stick to portable ground panels.

Running panels installed with just tape can kill someone.
 
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