Attaching a solar panel to the roof

[rlmankin]

I'm looking into adding a 100+ watt solar panel to my 31SL. I'm not sure how best to attach the panel to the roof. I've seen some people use simple lag screws, but that seems a weak method to hold the panel down during 65mph drives or high winds. I've thought about trying to find the metal roof joists, but I'm not sure how to do that. I thought there would be no better place to ask this question then the forum.

So... how do y'all attach a solar panel to the roof to be reliable and strong? Thanks in advance

Robb
2013 GMC Denali HD
2014 31SL - Stock

[trfield58]

Originally Posted by rlmankin

I'm looking into adding a 100+ watt solar panel to my 31SL. I'm not sure how best to attach the panel to the roof. I've seen some people use simple lag screws, but that seems a weak method to hold the panel down during 65mph drives or high winds. I've thought about trying to find the metal roof joists, but I'm not sure how to do that. I thought there would be no better place to ask this question then the forum.

So... how do y'all attach a solar panel to the roof to be reliable and strong? Thanks in advance

Robb
2013 GMC Denali HD
2014 31SL - Stock

I've attached several solar panels since owning fifth wheels, including 2 SOBs....I've always used stainless steel screws (2 per mounting leg) through the bracket and directly into the roof deck. I don't worry about hitting a roof joist. I put self-leveling roof sealant under the leg and op top of the screw heads after application. I then put a piece of Eternabond tape over the leg to add a bit more protection against leaks, etc. I've never had a problem and I do check the panels everytime I'm up on the roof for routine maintenance.

[rlmankin]

Thank you for the information. What size lag screws did you use? I was thinking 3/16 x 3"?

[travelin' texans]

I don't have the panels, but to me 3" would be about an 1 1/2-2" too long, the roof is most likely not more than 1/2" decking

[johnboytoo]

Have seen many that use just high strength adhesive to hold them on... no holes in the roof...

[trfield58]

Agreed, 3" screws are too long. I used 1 1/4" which are plenty long enough. As far as using adhesive such as 3M 5200 Marine...I wouldn't feel comfortable using that on the rubber membrane roof because you would be "gluing" to the rubber membrane which could easily separate from the roof deck. I know guys use the adhesive on fiberglass roofs and it is the best way to go.....

[atom ant]

Originally Posted by johnboytoo

Have seen many that use just high strength adhesive to hold them on... no holes in the roof...

Oh that may be OK for a fiberglass roof, but don't do that to a rubber roof as it may cause separation of the glue and lifting of the membrane off of the substrate.

My satellite antenna only used 1/2" or 3/4" screws.

[rlmankin]

Thanks everyone for the quick replies. I think I now know what to do when the snow melts. I appreciate the wealth of knowledge of this group.

Robb
2013 Denali HD
2014 31SL - Stock

[ted 95]

Originally Posted by johnboytoo

Have seen many that use just high strength adhesive to hold them on... no holes in the roof...

When I had my Scepter that is what I did, but the roof was fiberglass. I contacted Sika and told them my application. They supplied me with the same stuff that they use to install the roofs of Prevosts. What I did was glue 10' lengths of aluminum electrical strut channel (p1000) to the roof. I had 2 sets the full length of the coach. Then I installed 7 panels on each side. 12 coach and 2 engine. With the strut and the spring nuts I was able to place the panels where I wanted and NO holes. Also I could remove a panel for repairs easily. That was on a 2006 and I have been told they are still on the unit.

[atom ant]

Originally Posted by ted 95

When I had my Scepter that is what I did, but the roof was fiberglass. I contacted Sika and told them my application. They supplied me with the same stuff that they use to install the roofs of Prevosts. What I did was glue 10' lengths of aluminum electrical strut channel (p1000) to the roof. I had 2 sets the full length of the coach. Then I installed 7 panels on each side. 12 coach and 2 engine. With the strut and the spring nuts I was able to place the panels where I wanted and NO holes. Also I could remove a panel for repairs easily. That was on a 2006 and I have been told they are still on the unit.

Like I said, fine on fiberglass - foolish on membrane.

If air under a seal can separate the glue and create a balloon destroying the roof, you can imagine the pull from solar panels trying to separate that membrane from its glue. Warranty would probably be toast as well.