Solar Panel Install

[Capebuild]

I'll be installing 2 flexible solar panels to the roof. I have 2 questions.

1) Is it necessary to leave a small air gap between the roof and the underside of the panel.

2) any thoughts on what the best way of adhering them? I was first thinking of using Sikaflex 252 but I started thinking of maybe using VHB tape (which would create a bit of space between panel and teardrop roof)

Any thoughts would be appreciated.

Thanks

John

[tony.latham]

1) Is it necessary to leave a small air gap between the roof and the underside of the panel.

Perhaps for some, but my Renogy doesn't need a gap. That's from my experience and from what Renogy says.



I used screws to attach mine using the grommeted holes. But I adjusted my spars to those locations and added an extra grommet to the front. If I recall, Renogy mentions some kind of adhesive that may be used.







Tony

[cjlangellier]

I have a Renogy flexible solar panel on my camper. I used 3M VHB tape to mount the panel and have been very happy with it so far. We've traveled about 5000 miles with the trailer most of that on the interstate at max speeds of 80mph without issue. While an air gap is not required, you are right the VHB tape does leave a very small air gap between the panel and the roof. I have seen at least one Renogy blog in which they mention VHB tape as an option for mounting the panels. My only concern with this method is how easily will the panel come up if I ever need to have it replaced, but it does provide a clean looking install without putting additional holes in the roof.

[Capebuild]

I used 3M VHB tape to mount the panel and have been very happy with it so far

Thanks for the thoughts Tony and Cody.

Cody, when you mounted the panel using VHB tape.... can you be a bit descriptive in how you did it? Did you run strips parallel to each other on the sides? And maybe one in the middle.... or did you put tape around the 4 sides? I guess you'd have to leave openings to get the air flow.... Was just wondering how you laid out the tape??

Thanks

John

[cjlangellier]

I ran tape horizontally on the top bottom and middle of the panel. I left the ends open to drain water. When I was researching the tape method, I remember seeing that you don’t need to use full strips of vhb down the panel, you can get away with 4” on 4” off tape pattern, but I ran a solid strips from end to end. I was nervous about trusting the tape to hold the panel down. I think that was probably overkill now that I have a little more experience with the tape. They use this same stuff to bond the aluminum panels together in rivet-less cargo trailers.

[cjlangellier]

I ran tape horizontally on the top bottom and middle of the panel. I left the ends open to drain water. When I was researching the tape method, I remember seeing that you don’t need to use full strips of vhb down the panel, you can get away with 4” on 4” off tape pattern, but I ran a solid strips from end to end. I was nervous about trusting the tape to hold the panel down. I think that was probably overkill now that I have a little more experience with the tape. They use this same stuff to bond the aluminum panels together in rivet-less cargo trailers.

[TCJ]

John,
I was just at the Roadtoad/Camp-Inn factory and they showed me how they do it. They use VHB tape, but are careful to leave some gaps so water can drain if it gets under the panel. Obviously those gaps are on the low side of the panel, but also some along the sides.

[bdosborn]

John,
I was just at the Roadtoad/Camp-Inn factory and they showed me how they do it. They use VHB tape, but are careful to leave some gaps so water can drain if it gets under the panel. Obviously those gaps are on the low side of the panel, but also some along the sides.

That's what I did, VHB with gaps at the corners for water to get out. Its been working since 2012...


Boxcar flexible panel install
Bruce

[Capebuild]

Thanks for all the feedback. After pondering all this a bit, here's what I came up with how to install the panels.

First off I had found this video on YouTube by Brian of RVwithTito. I liked his system he came up with and I made a few adjustments using his method as a starting point. Here's a link to his video. https://youtu.be/uJIEXhnF8MU. I really liked using this polycarbonate material with the channels molded into it. I think it will support and elevate the panels off the roof of the trailer and provide some nice air flow with those channels. I wanted to avoid any sag that might develop over time, so I added some spacers between the bottom of the polycarbonate and the roof of the trailer. I also expanded the air/water flow channels a bit.

Below are some images of what I designed. I also liked the use of the T channel molding which provides for the panels to be elevated and a way to insert bolts to pass through the grommets on the panels to hold them down. I suppose there's a fine line between having the openings to provide air flow and a way for water to drain out but not have them too large so to avoid any air lift while driving that might want to try and lift the panels skyward.

Any comments are welcome.
Thanks

John
EDIT: One thing I meant to mention.... I don't know how long these panels will last (hopefully at least 3 years).... but with this method of install I think they will be fairly easy to swap out with new panels when the time comes for any replacement.

[tony.latham]

When installing those flexible solar panels on your roof, a couple of things to consider: About leaving a small air gap between the roof and the panel it can be a good idea for ventilation and preventing heat buildup. However, it's not always mandatory, and it might depend on your specific setup and how well the panels are sealed

Ralph:

Do you know that from experience?

As stated above, I have two panels. The Renogy flexible on the roof, and a glass panel on the tongue box.



The flexible gets slightly warmer than the cabin surface--just what you might expect from something black. The glass panel on the tongue box gets really-really warm. Much hotter than the flexible.

And thus, I think this bit about needing a ventilation gap is a myth.

Tony

[TimC]

I've changed my mind about flexible panels in the last few years. I think the first batches that manufacturers were marketing were not as durable as units manufactured recently. I don't have any first hand experience with flex panels as I used to believe the warnings about them so I steered away. Recently there have been good reports about the flex panels and I tend to now believe that if the panels are not handled regularly, like Cosmo did with his first ones, they will last a long time.

While heat build up does effect efficiency I don't think it hurts the panel physically to mount directly to a surface unless that panel is exposed to the direct sun continually. Obviously it is better to have ventilation under the panel since the cooler the panel stays the more efficient it will be. I have a rack mounted 1800 watt solar array at home and the panels will perform almost to rated capacity on a cold sunny winter day compared to around 85% of capacity on a hot sunny summer day. Panels mounted to a roof will often lose some efficiency due to heat buildup. It's not critical and most installations just put an extra panel or two to compensate for losses.

With the recent feedback I've read on flex panels I am considering one for my new Foamie roof instead of deploying a 100 watt panel I normally use.

[tony.latham]

With the recent feedback I've read on flex panels I am considering one for my new Foamie roof instead of ...

Stay away from the cheap junkers made from PET plastic. The Renogy panels--and others--are made from ETFE.

Tony

[RJ Howell]

I've changed my mind about flexible panels in the last few years. I think the first batches that manufacturers were marketing were not as durable as units manufactured recently. I don't have any first hand experience with flex panels as I used to believe the warnings about them so I steered away. Recently there have been good reports about the flex panels and I tend to now believe that if the panels are not handled regularly, like Cosmo did with his first ones, they will last a long time.

While heat build up does effect efficiency I don't think it hurts the panel physically to mount directly to a surface unless that panel is exposed to the direct sun continually. Obviously it is better to have ventilation under the panel since the cooler the panel stays the more efficient it will be. I have a rack mounted 1800 watt solar array at home and the panels will perform almost to rated capacity on a cold sunny winter day compared to around 85% of capacity on a hot sunny summer day. Panels mounted to a roof will often lose some efficiency due to heat buildup. It's not critical and most installations just put an extra panel or two to compensate for losses.

With the recent feedback I've read on flex panels I am considering one for my new Foamie roof instead of deploying a 100 watt panel I normally use.

Two things that keep me from mounting panels on my rig:
First: I have a DC/DC setup and when traveling, I'm charging. No matter what the weather. Love it!
Secondly: Orientation to the sun. You have to park in the sun and hopefully it's not hot climate your in. Then it's much easier to turn a portable setup for best gain then move the trailer (or in my case entire truck). Then comes angle to the sun. Tears are curved.. Square's well, how close to the equator are ya? Even folks I've met on the road with tilt panels, I wonder how much better gain over a good set of portable?

I've put my portable setup over my windshield in the southwest when I couldn't get shade. Block sun from my dash & gain power.. win/win. I have found so many places I could park in the shade and set out my portable in the sun. As we return from a hike, re-position it.

I'm sure others will say the 'Pros' of the mounted panels. I just don't see them.. 200w of panels and hope for 100w's of gain..

I'm a Portable panel dude, as you've noticed. I've debated the mounted over the years, yet I'm still a portable panel dude.
Only My Humble Opinion

Safe Travels!

[TimC]

...Orientation to the sun. You have to park in the sun and hopefully it's not hot climate your in. Then it's much easier to turn a portable setup for best gain then move the trailer (or in my case entire truck). Then comes angle to the sun. Tears are curved.. Square's well, how close to the equator are ya? Even folks I've met on the road with tilt panels, I wonder how much better gain over a good set of portable?

...200w of panels and hope for 100w's of gain..

All very true. Then there's the option of a mounted panel and still carrying my 100W portable for just those instances you mention.

[bdosborn]

While heat build up does effect efficiency I don't think it hurts the panel physically to mount directly to a surface unless that panel is exposed to the direct sun continually. ..

FWIW, the issues I've read about lately regarding heat buildup from flexible solar panels adhered directly to a roof have been campers with TPO membrane roofs. The extra heat can cause the membrane glue to fail and the roof comes loose under the panels.
Bruce