Installing flexible solar panels to roof

[k corbin]

I am a believer in following the instructions for installation from the company you purchase them from. Failure to do so will void any warranty you might have gotten from that company.

The companies that sell you the solar panels want them to perform right for you. That is why they test the installation methods so they can pass on the best methods for best results. But of course there will always be people who think they are more clever than the professional installers. Once in a while it is even true but not generally this many years after there has been proven success in how to install flexible solar panels. Don't over think it. Just follow the instructions.

[tractors1]

Originally Posted by Markz

There must be a method of effectively removing VHB from fiberglass?

I've used hundreds of rolls of industrial grade 3M foam double sided VHB tape on fiberglass for my products and worked with 3M tape engineers for 20+ years.



Removal on fiberglass is straightforward - but the parts cannot be pulled apart. Use either dental floss or monofilament fishing line to "saw" through the foam center of the tape, thereby separating the parts, then "roll" the tape off both parts. Any residue on the fiberglass can be removed with either fingernail polish or acetone (main ingredient in nail polish.)



On your part, try a bit of acetone to test if it will damage your part. It will dissolve almost any plastic!

[Byron Kinnaman]

Originally Posted by Markz

There must be a method of effectively removing VHB from fiberglass?

There is it's called dental floss.

[Ak Ron]

I put a 100w flex panel on my trillium outback using eternabond and sealed the edges with dicor. Fits well with nothing to catch air or to see from the ground except some wires.
I don’t worry about the output reduction due to heat as if it is hot that means it is sunny and I am getting all the charging I need anyway.

[GaryM]

We have a 2015 Alto R1713 by Safari Condo. The flexible PowerFlex PFM-2K, 95 watt solar panels (190 watts total) were installed by Safari Condo during the construction of the camper. They are glued directly to the roof without any need for ventilation under the panels. We camp about 140 nights per year and have towed the camper 37,757 miles. The panels work great and are still attached in their original positions. We recently spent 5 days in Rocky Mountain National Park with no hookups. They worked great!

[Davo]

Anybody have experience and product recommendation on MPPT (vs older technology PWM) charge controller between panels and battery?

[Fallon]

Originally Posted by Davo

Anybody have experience and product recommendation on MPPT (vs older technology PWM) charge controller between panels and battery?

http://www.bogartengineering.com/support/faq.html
https://handybobsolar.wordpress.com

[GaryM]

Originally Posted by stude

I have now talked to several solar dealers who also install them and 5 out of seven say leaving a gap for air movement is important to keep the area under cool. I use Rigid for this reason only, at one time the Flexible S. Panels were not that good but maybe now they are better.
Stude

Evidently, there are different requirements for flexible panels made by different manufacturers. The video at https://tinyurl.com/yaso3ckz was made by Powerflex and, while not an RV application, there is no mention of ventilation under the panels. They show the panels being adhered directly to the roof.


There are too many mechanics, dealers, installers out there who think they know more than the people who designed, engineered and built a given product. I always go with the instructions from the manufacturer.

[David in Maryland]

Originally Posted by Markz

I am interested in installing a pair or flexible solar panels to the roof of our Boler.

If you're intent on raising the panels and since the panels are flexible, maybe a compromise between raised and glued down would work. I'm thinking you could arc the panels, with several risers in the middle, the end that would face the wind as you're driving glued down and the other end also glued down for added bonding strength. That should decrease the possibility of them breaking free, catching enough wind to tear it off and still allow for some airflow underneath.

[tractors1]

Originally Posted by David in Maryland

If you're intent on raising the panels and since the panels are flexible, maybe a compromise between raised and glued down would work. I'm thinking you could arc the panels, with several risers in the middle, the end that would face the wind as you're driving glued down and the other end also glued down for added bonding strength. That should decrease the possibility of them breaking free, catching enough wind to tear it off and still allow for some airflow underneath.

Crosswinds from passing vehicles (think semi trailers) and storms were deemed to be the cause of lost rigid solar panels on Escape trailers a couple of years ago. The mounting rails were epoxied to the trailer, but with the right combination of winds the whole shebang would fly off the trailer as the epoxy held well enough to rip the gelcoat off the fiberglass.

[David in Maryland]

Originally Posted by tractors1

Crosswinds from passing vehicles (think semi trailers) and storms were deemed to be the cause of lost rigid solar panels on Escape trailers a couple of years ago. The mounting rails were epoxied to the trailer, but with the right combination of winds the whole shebang would fly off the trailer as the epoxy held well enough to rip the gelcoat off the fiberglass.

So... maybe my suggestion turned 90 degrees? Or gluing down the sides with a riser or two long ways? Just spitballin' here...

[Jim Bennett]

My suggestion, do as I did following manufacture recommendation and fasten the Lensun flexible panels directly to the roof. They claim it works great and the panels can handle it, and I find it true too. When a good, simple and effective method is available, why try to complicate it?

Unless you want to orient your panel into the sun for the most effective solar gain, this method works just fine. I know I am only 1 1/2 years into using them mounted this way, but as reported all is still fine.

I have done lots of mods to my trailer with many more planned, so keeping some things as simple as possible means I get more done. I will not knowinly compromise a quality install though.

[David in Maryland]

I agree - simply fastening the panels to the roof would be ideal. But, as a confirmed tinkerer who constantly looks at ways to modify things, I was trying to accommodate the OP's request to get some cooling under his panels.

[Roger M]

Originally Posted by Markz

There must be a method of effectively removing VHB from fiberglass?

AM Solar has excellent DIY instructions and videos:

https://amsolar.com/rv-solar/support/

VHB tape removal title is "Removing The Rocker Feet". It's remarkably easy.

[tractors1]

Originally Posted by Roger M

AM Solar has excellent DIY instructions and videos:

https://amsolar.com/rv-solar/support/

VHB tape removal title is "Removing The Rocker Feet". It's remarkably easy.

I wouldn't be scraping/scratching the gelcoat with a metal blade putty knife. I find cutting the tape center with dental floss or fishing line to be simple, then use a little acetone to soften up the adhesive on the two halves of the cut tape. No harm done to the gelcoat.

[Roger M]

I wouldn't advise scraping the gelcoat in the same manner as demonstrated in the video either. It took all of 30 seconds to remove the foot in the first example. Using a plastic putty knife and more care in pushing the alcohol into the tape should leave the gelcoat in fine shape.

IIRC AM Solar stated in a phone conversation they have never had a VHB tape failure and they've done thousands of installations.

3M VHB tape when installed properly works very well and can be removed easily, either method you choose.

[Grandfatherjim]

I am on here because I have a Trillium, but I also have an Adventurewagen, which is a VW van conversion with a solid fibreglass top. I think my question could apply pretty well to other FG RVs so here goes.

I have two flexible solar panels that I want to affix using Eternabond, one in front of and one behind the vent in the roof. However the roof has two wide ribs running lengthwise, and the panels are big long enough to span the full width of the roof.

You can see that I could mount the front panel far enough forward that the leading edge would lie flat where the ribs flatten out (picture on the right), however for the trailing edge, I'll have to deal with the 7/8" height of the ribs. One solution could be to add 7/8" of something between the ribs so that the panel wouldn't be forced to flex around them, as they are not so flexible that they could do such tight bends. But this would trap air and maybe eventually water underneath and if the air can't move I can't see how it would help significantly with cooling.

Or, I could mount it a bit further back, and only tape the panel down where it lies on the ribs (and the sides). This approach gives it pretty good cooling but seems risky as there isn't too much attachment area where the panel lies on the ribs and I worry they might blow off while driving.

The rear one is kind of the same thing in reverse, as the ribs flatten out toward the rear (toward the snow in the first picture). Here though, I have another decision to make - I could turn the panel 90 degrees so it lies partly on the area that tapers down toward the rear. This has the advantage that when parked, I can catch sun more hours per day with the rear panel. But in that case I really would have to close off the front side, or it seems pretty certain it would rip off in the wind.


Thoughts?
Thanks,
Jim
PS dirty roof eh? Someday I hope to have indoor parking....

[Thomcat316]

Originally Posted by Markz

There must be a method of effectively removing VHB from fiberglass?

Use a relatively thicker VHB foam tape appropriate to gelcoat, and use one of the new braid fishing lines to cut through the foam when you want to remove it. 3M suggests liquid soap as a cutting lubricant.

The following is from a PDF on VHB tape removal:

Removal of adhesive residue:
To remove residual adhesive from the disassembled parts, several methods are useful:

• 3M™ Stripe Off Wheel
The Stripe Off Wheel (part number 07498) is a special rubber disk which mounts to a standard 3/8" electric
drill. When the rotating disk is brought in contact with the adhesive residue, it lifts the adhesive from the
surface. When used properly the wheel does not damage painted surfaces. It helps to remove the bulk of the
adhesive foam residue with a razor scrapper or knife before using the wheel. This operation can be followed
up with a cleaner wipe to remove debris.
Note: Follow all safety instructions for the use of the Stripe Off Wheel (included in packaging) and for
operation of any power tools.

• Abrading
If surface damage is not an issue, residual adhesive can be removed with a porous abrasive disk or wheel.
A detackifying agent such as a detergent/water solution or dry talc may be used to facilitate removal and help
prevent clogging of the abrasive. Low speeds are generally more effective than high speeds for removal to
prevent excessive heat buildup. Once the adhesive is lifted off the surface, a cleaner wipe can be used to
remove the debris.

• Solvents
The adhesive residue can be wet with a solvent then covered with a plastic film and allowed to soak for 5-15
minutes. Once the adhesive is softened, use a scrapper to remove the adhesive. Solvents to use include:
• 3M™ Citrus Base Cleaner • Automotive Bug-and Tar remover
• MEK (Methyl-Ethyl-Ketone) • Other commercial adhesive removers