Community Forums

cactus bum · 02-15-2019, 08:30 AM

I have a 2018 Forester 2291S. I need to install solar panels and have no roof studs to attach to. I have a pebble textured fiberglass roof that is backed with 1/8" Luan with foam core under that. Aside from the occasional "backer" of 1/8" metal where the mfg needed extra support, there are no studs. The pebble surface of the fiberglass makes me think 3M VHB tape will not do the job as it easily would on a smooth roof. Has anyone dealt with this and solved it? Thanks,

Michael

LJowdy · 02-15-2019, 08:47 AM

I had solar panels on a previous coach. I used "blind rubber nuts" See link.
You drill a hole in your roof then insert the rubber nuts and they compress when you tighten the bolt. I also added a generous amount of Dicor sealant round each rubber nut.

https://www.amazon.com/Hillman-Group...28738130&psc=1

cactus bum · 02-15-2019, 10:29 AM

[QUOTE=LJowdy;4636916]I had solar panels on a previous coach. I used "blind rubber nuts" See link.
You drill a hole in your roof then insert the rubber nuts and they compress when you tighten the bolt. I also added a generous amount of Dicor sealant round each rubber nut.

What exactly were you dealing with as a roof. Was there a thin layer of fiberglass and a thin layer of Luan like mine?

Dutch Star Don · 02-15-2019, 10:27 PM

I just attached panels this week. I've done them the same way several times with no issues. I use butyl rubber tape, just like they seal windows with, under each bracket. It will stick and conform to the roof, while leaving a waterproof seal.

https://www.homedepot.com/p/Fabral-1...YM4w&gclsrc=ds

Once the panels are in place with the tape, I use stainless steel screws (pre drilled) and screw the brackets to the roof. When all done, I cover the brackets and screws with Dicor.

LJowdy · 02-16-2019, 05:54 AM

The roof on the Tour was similar to what you have. I've seen these used on a whole variety of different coaches and different roofs.

cactus bum · 02-16-2019, 09:31 AM

Quote:

Originally Posted by Dutch Star Don

I just attached panels this week. I've done them the same way several times with no issues. I use butyl rubber tape, just like they seal windows with, under each bracket. It will stick and conform to the roof, while leaving a waterproof seal.

Once the panels are in place with the tape, I use stainless steel screws (pre drilled) and screw the brackets to the roof. When all done, I cover the brackets and screws with Dicor.

Was your roof the pebble textured kind? Also, with respect, the butyl tape has low adhesive properties, but makes a fine hole sealer. I would vote for the VHB tape myself rather than Butyl. Dicor over it all makes perfect sense. Thanks for the response. Michael

cactus bum · 02-16-2019, 09:39 AM

Quote:

Originally Posted by LJowdy

The roof on the Tour was similar to what you have. I've seen these used on a whole variety of different coaches and different roofs.

Thanks for the post. Any specific advice on installing these fasteners? These expansion nuts are offered in various sizes. What diameter did you use? Would you advise using the VHB tape under the feet also, along with the expansion nuts, then Dicor self leveling over all?
This kind of attachment seems scary to me, but as it is a proven method I have to consider it. Anyone else with experience who can and will chime in would be appreciated. Thanks for the help LJowdy. Michael

cactus bum · 02-16-2019, 09:46 AM

I have heard debate over using either coarse thread stainless screws or fine thread ones for securing into what is essentially a 1/8" Luan layer with a very thin fiberglass layer on top. I have gotten both answers, coarse and fine, with arguments for both. IF screws are used in this roof, what thread? Thanks, Michael

Dutch Star Don · 02-16-2019, 10:25 AM

Two of the roofs that I installed panels on were fiberglass and one was aluminum (Monaco Diplomat). Butyl rubber may not have the best sticking qualities, but you'll cuss trying to remove it later. Remember, not much will stick to your style roof. You're looking for something that seals over the dimples. Neither fastener, the screw or the tape is there to secure the bracket individually. The combination of the tape and screws, topped with Dicor are a system. I find the coarse threads are less likely to strip out in this application. I use a screw gun to apply after pre drilling and then do the final tighten by hand. My first two installations NEVER came loose or leaked. My installation this week saw more rain in three days than California typically sees in three months.

cactus bum · 02-16-2019, 12:07 PM

Thanks Don for the info. Sounds like you have the system dialed in, and proved it with the current weather pattern we in Arizona are sharing with you. Thanks for taking the time to post. Michael

LJowdy · 02-16-2019, 07:24 PM

You asked which expansion nuts I used. I found ones that use a 5/16" bolt. Drilled holes in the roof, pushed in the expansion nuts then tightened the bolts. I also applied a liberal amount of Dicor. NO LEAKS, ever

cactus bum · 02-17-2019, 07:54 AM

Quote:

Originally Posted by LJowdy

You asked which expansion nuts I used. I found ones that use a 5/16" bolt. Drilled holes in the roof, pushed in the expansion nuts then tightened the bolts. I also applied a liberal amount of Dicor. NO LEAKS, ever

Thanks for the info. I wonder if your plywood is more substantial than my 1/8" Luan. I suspect your very nice coach might have 1/4" or even 1/2" ply, which would make ALL THE DIFFERENCE. Can you remember if the ply was 1/8"? Sorry to seem to nit-pick, but the stakes are high and every detail is quite important to the solution. My problem is the danged 1/8" Luan. Thanks, Michael

SSTraveler · 02-17-2019, 08:18 AM

I did not want to drill holes in my roof for my solar panel install so I used 1/4×4×6" pieces of aluminum and put a 1/4" machine screws through it to install the solar feet to and used 3M VHB 4952 to stick the plates to the roof and then covered them with 3" Eternabond tape and then tightened the solar panel feet to the aluminum plates with lock washers and nuts. But recently I found these Renogy tilt brackets, https://www.renogy.com/renogy-rv-tilt-mount-brackets/, that I would use next time. I would VHB them down and cover with Eternabond tape. With the much larger surface area they would be even more secure and Eternabond tape sticks to anything. I have seen that others only use Eternabond with 100% success. I just like redundancy in adhesion types. I like the tilt mounts because in the winter the sun is much lower so I could tilt my panel up towards the sun and get better efficiency for charging my batteries while in winter storage.

Unplanned Tourist · 02-17-2019, 08:43 AM

Quote:

Originally Posted by SSTraveler

I did not want to drill holes in my roof for my solar panel install so I used 1/4×4×6" pieces of aluminum and put a 1/4" machine screws through it to install the solar feet to and used 3M VHB 4952 to stick the plates to the roof and then covered them with 3" Eternabond tape and then tightened the solar panel feet to the aluminum plates with lock washers and nuts. But recently I found these Renogy tilt brackets, https://www.renogy.com/renogy-rv-tilt-mount-brackets/, that I would use next time. I would VHB them down and cover with Eternabond tape. With the much larger surface area they would be even more secure and Eternabond tape sticks to anything. I have seen that others only use Eternabond with 100% success. I just like redundancy in adhesion types. I like the tilt mounts because in the winter the sun is much lower so I could tilt my panel up towards the sun and get better efficiency for charging my batteries while in winter storage.

I did the same and am very happy. I used the same urethane material that holds windshields in your cars and pickups, very strong, yet pliable. Just be very sure to clean both surfaces very good with alcohol and leave it to set up for 24 hours.
Happy Glamping.