I am planning on installing 1600 watts of solar on my U270. I plan on using VHB tape as well as screws for mounting. Does anyone who has used VHB tape for solar mounting know if the type of roof coating in the attached photo would interfere with the tape? I don't know exactly what type of coating it is as it was on the coach when we purchased it. Also, for those who have used screws, how long should the mounting screws be to hold securely in the plywood and/or the aluminum ribs beneath the fiberglass?
Dave and Kathy Bennett
2004 U270
No matter what happens, remember you always get the trip out of it.
Hi Dave and Kathy,
I mounted 10 panels 7 years ago using VHB only. Since then I have had the roof painted and re-adhered again the panels with fresh VHB. No screws used ever.
None of the solar panels have ever let go. Lots of hot and freezing weather over the years and my coach has never been stored inside.
My only prep was to wash with water, then scrub with alcohol then let it dry before placing the VHB for each foot.
I have been amazed and do check them once in awhile just to be sure they are OK. VHB allows some movement from the foam layer so the bond isn't stressed.
Jim
2002 U320 42'
Dave, Kathy- I can share how we accomplished our install. I mounted seven standard commercial solar panels on our coach last spring, we drove about 11,000 miles over seven months this year without any problems.
We took the advice from many others on this forum in regard to mounting... VHB tape is a great method to mount solar panels. It's of the utmost importance to follow the manufacturers recommendation for surface preparation. Search "Solar install", lots of info here on the forum...
I can't discern what surface paint or product is on your roof, however I know that VHB tape needs a smooth surface to promote the best adherence. Our roof was painted with a course anti-slip automotive paint, likely included a crushed glass additive. I carefully marked where the "feet" were going to layout. I then sanded the finish down to the gel coat to acquire a smooth surface.
Your choice of mounting hardware is also important! There are lots of forum information about sizes of the mounting bracket, and the angle of our roofs to "bracket-to-solar panel", (you want 90 degrees at the panel)... Your choice of Solar panel will determine bracket size... Follow all the recommended application tips, cleaners and primers for VHB tape.
For my install I used oversized brackets, (Roger's aluminum bracket design) with 1 1/2" VHB tape, and screws. I also sealed the brackets with 5200 sealant on all edges and then Eternabond tape over brackets and onto the roof surface. Overkill? Maybe, but I was a commercial Solar installer, so my experience leads me to be cautious...
I don't recall the screw size, will check when we're back home in a few weeks. It's hard to line up the aluminum ribs exactly with the mounts, I think I was only able to hit three panels on one side.
You can check the roof thickness by taking off your vent above the microwave, look at the cross section of the roof, (learned this tip from John Fritz).
PM me if you need any other info.
Best, J & K
Jeff,
I love your approach. Talk about belt and suspenders! I suspect that VHB tape alone would be adequate, I am sure 3M 5200 alone would be totally sufficient and screws with Eternabond would be a good choice on their own.
Richard
Check out the video at AM Solar. You would need to sand roof smooth for 3M tape. Seal edges of mount with 4200 3M sealant. I did not use screws. Three years and 30,000 miles, five panels. Made my own aluminum mounts
Do you have a photo of the mounts you made? I have been looking at different ways of making my own, but I haven't settled on a plan yet.
Dave and Kathy Bennett
2004 U270
No matter what happens, remember you always get the trip out of it.
There are many kinds of VHB tape from very thin films to much thicker tapes that have more flexibility to adapt to uneven or not quite parallel surfaces.
This is the one I used. https://amazon.com/gp/product/B00HLY7BBO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
My best guess is that you should figure out where the mounts will fit, mark with painter's tape, and sand the coating off just to the gel coat. Clean carefully with toluene, don't use alcohol, it inhibits the VHB tape adhesion. Then use a 3M VHB tape surface prep and adhesion promoter. https://amazon.com/gp/product/B00745Z8BK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Once the mounts are set in place, wait overnight and caulk around all four edges. You can use the 3M 5200 but if you ever have to remove a mount it is very tough. 3M 4000 fast cure UV resistant caulk is almost as tough and removable (with some serious effort. Amazon.com: 3M Marine Adhesive Sealant 4000 UV, PN06580, White, 295 mL... (https://amazon.com/gp/product/B000XBDJWC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
I used no screws into the roof.
I made all of my own solar mounts and enough more for about 20 more panels for other coaches. The bottom section is 92° so that when using a standard 39" wide panel the part that mounts on the roof is parallel to the curve of the roof. My metal fabricator makes up the parts for me in 6' sections. I cut them to 12" lengths and drill all the holes using jigs so the holes all lineup. They can be other lengths as needed but the panels I have seen have mounting holes 10" apart on the long side of the panel frame.
Two sets of holes let you adjust the height. The longer vertical leg helps support the panel. The shorter angle can be a standard aluminum angle. I use 5/16" stainless bolts and nylock nuts, be sure to use an anti-seize lube. A quality plated bolt and nut will work just as well without any of the negative stainless bolt and nut issues.
Of course there will be other opinions. How you mount your panels is your choice. There was no way I was going to use a small 3"x1" mount or some size like that. Better safe than sorry.
The 3M 5200 alone requires very careful surface prep, clamping, and at least a week to develop full cure. As a sealant it is fine but not so much as an adhesive for the purpose of mounting solar panels to the roof of your coach.
Here is what I built. 1.5 inch aluminum angle. Panels were 180w. They angled to fit slope of roof. Not as robust as Roger's.
looks like you're overdue for gutter cleaning! :))
Those are some sturdy looking mounts. I appreciate all the info, both here and in your other posts on your solar project.
Dave and Kathy Bennett
2004 U270
No matter what happens, remember you always get the trip out of it.
Those look a lot like the (very expensive) mounts from AM Solar. Did you use 1/8" thick angle?
Dave and Kathy Bennett
2004 U270
No matter what happens, remember you always get the trip out of it.
I did copy (more or less) the AM Solar mounts, except mine are less sophisticated. I used 1/8" angle and mine have twice the surface mounting area of the AM Solar mounts. They can be tilted if I ever get around to making tilt bars. They were very tedious to make with lots of cuts, and lots of drilling on the drill press and on the panels. I used a piece of 1x4 as a backer when drilling into the panel frame, did not want to drill past the panel frame and into the solar panel itself. There are actually seven holes per mount (counting panel frame), times 20 for five panels. By the time I cut all the pieces, cleaned them up with a file, and drilled them, the "pricey" AM Solar mounts started looking like a bargain! Bought the angle at LOWES and the hardware at Tractor Supply. I'm not sure four AM Solar mounts would be adequate for the larger commercial panels many are now using on the Forum. Commercial panels are a great bang for the buck. Installed one 327 watt 58 volt panel on my son's trailer along with a Renogy blue tooth MPPT charge controller. Super affordable. I used Victron battery monitor and solar charge controller because I was too lazy to mount the control panels inside the RV, just use my phone over blue tooth.
If you are making you own mounts be very careful where you mount them to the panels. Most panel manufacturers have detailed drawing showing where you can and can not put panel mounts. If you are not using holes provided by the manufacturer it is likely that they shouldn't go there.