Fasteners for mounting solar panels

Big-B

Well-known member
I'm getting ready to mound a couple of 280 watt panels on the roof of our 34 foot Bighorn 5th wheel. I'm using a couple of 10 foot lengths of unistrut to mount them on and am wondering what kind of fasteners to use to mount the unistrut. I'm planning on using 1/4" stainless steel lag screws and hopefully hit the trusses or rafters in the process. Does this sound like a good plan and what kind of fasteners should I use?

If the roof on my Bighorn is the same as the one that I saw in another post it looks like it only has 3/16 wood on top of styrofoam.
 

SLO

Well-known member
I used these.

https://amsolar.com/rv-mounting-accessories/91m-35ms

Didn’t bother looking for trusses, just screwed into roof. Then put enough Decor self leveling caulk to completely cover screws and brackets. After 5 years and one trip to Alaska, no movement or leaks. My panels were 100 watts so a little bit lighter, 16.5 lbs. The brackets are very expensive, for 6 panels, but all metal is SS and no rust at all in 5 years. My experience, for what it’s worth.


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jbeletti

Director of Owners Interests, Heartland RVs
Staff member
I used stainless steel lag bolts. Can't remember the diameter - probably 1/4".

  • I pre-drilled the holes in the plywood with a smaller drill bit (probably 1/8")
  • I put butyl tape under each panel bracket where it would lie on the roof
  • I slowly installed the lag bolts through the panel brackets and into the roof
  • I used Dicor lap sealant to completely cover the lag bolt head and the entire panel bracket foot (about 1 square inch)
I suggest you use butyl tape on whatever part of your system (UniStrut) will contact the roof membrane where a fastener will be going through it. Then of course - lots of Dicor lap sealant.
 

Big-B

Well-known member
Thanks for the quick responses. I think tomorrow I'll pick up some of the tape for under the unistruts. I already have a tube of dicor and plan to drill a 1/8" hole in 5 places, then give each hole a nice shot of Dicor and put the lag bolts in. I have 1" lags and they will be about 3/4" into the roof which I would think will be plenty if the wood on the roof is as thin as I've read at 3/16".
 

jbeletti

Director of Owners Interests, Heartland RVs
Staff member
Thanks for the quick responses. I think tomorrow I'll pick up some of the tape for under the unistruts. I already have a tube of dicor and plan to drill a 1/8" hole in 5 places, then give each hole a nice shot of Dicor and put the lag bolts in. I have 1" lags and they will be about 3/4" into the roof which I would think will be plenty if the wood on the roof is as thin as I've read at 3/16".

Sounds like a perfect plan to me.
 

Big-B

Well-known member
Sounds like a perfect plan to me.

Thanks Jim. I should have 560 watts of solar panels mounted this week while it's still warm here in Michigan. Possibly mounting another two of the same panels on the front later.
 

jbeletti

Director of Owners Interests, Heartland RVs
Staff member
Thanks Jim. I should have 560 watts of solar panels mounted this week while it's still warm here in Michigan. Possibly mounting another two of the same panels on the front later.

You’ll never regret putting too much solar on the roof. I have 1080 watts. Would like a couple hundred more but I’m out of roof space.


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marknewbill

Active Member
It am pretty certain the answer is no, but is there yet any solar system that can run the AC unit yet, that would be great!
 

Oregon_Camper

Well-known member
It am pretty certain the answer is no, but is there yet any solar system that can run the AC unit yet, that would be great!
Solar will never directly run AC unit, as they require A/C power not D/C power. You can ( and I do) run your AC unit from battery bank, however you need to be prepared to drop ~$10k to get this working. ~1,500watt of Solar panels, 3000w inverter, large battery bank (~600Ahr of Lithium works great) and all of that installed. Might save ~$2k if you can do the install yourself.
 

marknewbill

Active Member
Solar will never directly run AC unit, as they require A/C power not D/C power. You can ( and I do) run your AC unit from battery bank, however you need to be prepared to drop ~$10k to get this working. ~1,500watt of Solar panels, 3000w inverter, large battery bank (~600Ahr of Lithium works great) and all of that installed. Might save ~$2k if you can do the install yourself.
Thats interesting, so how long will your setup operate the AC unit provided you had full sun, do you get a couple hours of use? or will it run all day or how does that look. I know it will matter how hot it is, so lets assume it it running full power all the time and never catches up.
Thanks,
 

Oregon_Camper

Well-known member
Thats interesting, so how long will your setup operate the AC unit provided you had full sun, do you get a couple hours of use? or will it run all day or how does that look. I know it will matter how hot it is, so lets assume it it running full power all the time and never catches up.
Thanks,
Great timing. I was playing with this yesterday and when I was running the bedroom AC unit, I was pulling a WHOPPING 165 amps. That means I could run the AC unit for about 3.5 hours on my 600Ahr of Lithium batteries (6x100). Now, I have nowhere near enough solar on the roof of our Bighorn (now at 600w) to keep up with the AC usage, but here in Oregon, we don't have a need to run the AC unit so it has been a moot point for our needs. Worse case I can fire up my portable Yamaha generator and then use both battery power and gen power to get more AC run time.

Battle Born just today announced their Summer sale, so they are starting at $100 off and some are even more than that. Here is a link. FYI...I am an affiliate with Battle Born.

 

marknewbill

Active Member
Great timing. I was playing with this yesterday and when I was running the bedroom AC unit, I was pulling a WHOPPING 165 amps. That means I could run the AC unit for about 3.5 hours on my 600Ahr of Lithium batteries (6x100). Now, I have nowhere near enough solar on the roof of our Bighorn (now at 600w) to keep up with the AC usage, but here in Oregon, we don't have a need to run the AC unit so it has been a moot point for our needs. Worse case I can fire up my portable Yamaha generator and then use both battery power and gen power to get more AC run time.

Battle Born just today announced their Summer sale, so they are starting at $100 off and some are even more than that. Here is a link. FYI...I am an affiliate with Battle Born.

thanks for the info. thats really pretty good info there. for me in the south the ac is mandatory. hopefully one day the tech improves so you can run the ac all the time. maybe someone will make a dc air conditioner like they make the dc fridges now.
 
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