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Old 06-29-2017, 10:10 PM   #1
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Default Unexpected response from 3M about VHB 4950 tape for rigid solar panels

I contacted 3M trying to get some help figuring out how to get appropriate width of VHB to get full coverage of some solar panel mounts I plan to use for some compact 40X20 inch 100W Renogy panels (not flex panels). I want to have the option to remove the panels in the future and feel they have advantages in terms of durability, failure risk, and output at high panel temps. The panel mounts have a base that is almost 4 inches long by 1.34 inches wide.The panels will be 1.2 inches off the roof surface when mounted. Not as stealthy as flex panels but not bad. I'd like to avoid screws, but would consider them - there are already screws up there.

I got the response below. ? Is this a CYA response? Maybe I should have expected it. I don't know which 3M tape # or how much they use to hold trucks together but it is not 4 sq inches per pound of weight supported. AMSolar's site says they use 4950 for mounting panels on Airstreams as well as fiberglass roofed RV's (but not rubber roofs).



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Thank you for contacting 3M, where we apply science to life.

I am not sure where you heard the 4950 VHB tape is frequently used for this type of application. We do not suggest that particular VHB, and in fact, VHB can be used for this application, but we suggest it in conjunction with mechanical fasteners. VHB was not intended for this application as a sole means of bonding it due to many factors. The 4950 tape is mostly used for metal to metal applications. We have other VHB tapes that will bond much better to fiberglass. I would suggest to test our VHB tape #5962 along with our adhesion promoter 111. We suggest to use 4 square inches of tape, per pound of weight it will support. I have attached the data page for review. Please read over all the application instructions as surface prep, how much tape to use, set up time, etc. is all listed. You won't need to get an exact width of tape for the width of the panels, as long as you can get the 4 sq. inches per pound around the diameter. Also, use the mechanical fasteners in addition to the tape. This is suggested to support the wind loads it will see going down the highway.

You can find these products on, R S Hughes, or Grainger, usually in smaller rolls or broken cases.

If you need further/additional assistance or prefer to speak directly with a specialist please call 1-800-362-3550 for the first available representative.
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