how to mount solar panel brakcets with screws/lag bolts

[John C]

On 5/1/2024 at 4:56 AM, Twomed said:

3M 5200 and a 1 inch rivet through 1/4 inch aluminum angle brackets....4 panels 600 watts 12 years...110k miles never garaged...still tight.  😄

Hi, @Twomed,

Getting ready to start the project, I am going to use 3M tape + Rivet just as you did.

Quick questions, did you install the rivet on the roof first? or  you glued the angle bracket on the roof first then install the rivet?

Did you use pop rivet or rivnut?

Thank you.

Edited June 20 by John C

[Twomed]

Panels are bolted to angle brackets with stainless 1/4 in bolts and nylok nuts.  Then positioned on the roof, 3M 5200 applied under each angle 1" long 3/16 aluminum rivets partially set, wait 24 hours and then set and snap the rivets.  

5220 is not a tape it is a caulk tube marine adhesive used to bed  watertight hull fittings on boats. Two kinds one that sets in about a week, messy, and one that cures in about 48 hours but is compressive in 24.  With either if you completely torque any fitting it squeezes the material thin of course and you may lose some sealing and adhesive properties.  It is one of 3M's strongest adhesives.  Check marine forums and West Marine's and 3m's how to forums for more info.  Don't plan on moving the panels once set...it can be done but the stuff is really bonding.  Belt and suspender guys cover the rivets with a dab of 5200 when done. 

Thirteen years, 110k miles fulltime, temp extremes 0 to 110, never garaged and no leaks or movement at all. 

[John C]

6 hours ago, Twomed said:

Panels are bolted to angle brackets with stainless 1/4 in bolts and nylok nuts.  Then positioned on the roof, 3M 5200 applied under each angle 1" long 3/16 aluminum rivets partially set, wait 24 hours and then set and snap the rivets.  

5220 is not a tape it is a caulk tube marine adhesive used to bed  watertight hull fittings on boats. Two kinds one that sets in about a week, messy, and one that cures in about 48 hours but is compressive in 24.  With either if you completely torque any fitting it squeezes the material thin of course and you may lose some sealing and adhesive properties.  It is one of 3M's strongest adhesives.  Check marine forums and West Marine's and 3m's how to forums for more info.  Don't plan on moving the panels once set...it can be done but the stuff is really bonding.  Belt and suspender guys cover the rivets with a dab of 5200 when done. 

Thirteen years, 110k miles fulltime, temp extremes 0 to 110, never garaged and no leaks or movement at all. 

I am so glad I asked you, I called 3M, they told me the holding strength of 5200 is 2-3 times of the VHB tap!

So I will use 5200.

Question, what kind of primer did you use ?

Also, do you have any problem with rivet on fiberglass, what kind of rivet did you use? I read some post, they claimed the fiberglass is too soft for the rivet and you have to those "Tri-Fold Exploding Large Head Aluminum Pop Blind Rivets" or put a washer in back of the fiberglass(of course it can't be done on fiberglass roof)

Thank you!

Edited June 20 by John C

[Twomed]

Acetone will clean it well enough.  If your gelcoat is real smooth or has been painted I would scuff it a  bit with a 400 grit paper.  Regular aluminum rivets are fine, just use the proper drill size.  ALWAYS run your drill backwards through the gelcoat then forward through the glass.  That will prevent spider web cracking around the hole.

Believe me the 5200 would hold it without a rivet.  Try some on some scrap and try to get I apart after a week just for kicks.

[scottknight]

My finishing skills are not my best skills, but I cleaned the roof and Dicor before and after. Fine thread counts on fastener to bite into thin aluminum skin. Been up about 6 years . Dicor brackets again last year, found nothing alarming. 05 Knight.