Solar panel fixing failure

[Rohsman]

I finally got round to fixing extra solar panel. Used Sikaflex 252 to stick ABS mounts to aluminium frame of solar panel. One of the ABS mounts I cleaned with acetone. 15 hours later was offering up solar panel on roof of motorhome and caught the mount and it came cleanly off the solar panel with no Sikaflex stuck to it. Sikaflex 252 hadn’t fully cured but was shocked how easily snd cleanly it came off! Any thoughts or advice? I will add bolts to other mounts but still need to stick ABS mount down to gel coat finished roof.

 

[Jimbohorlicks]

It's best to mask off the roof area where the mounts are to go and roughen the intended fixing surfaces with emery to remove the gel coat.plus roughen the plastic mounts or even drill the underside to create several holes to allow the sika flex to go through. Not sure if acetone is the best thing to use as this may soften any paint etc and mat affect the plastic mounts. Simplex sell a cleaning agent and activator which would be better than acetone imo.
When applying the sikaflex use tile spacers or matchsticks to create a layer of sikaflex between the mounts and roof rather than squeezing it all out.

 

[Lenny HB]

We're you using the correct Stika as a lot are not suitable for plastic.

Bin the abs mounts and use aluminum they rarely ever fail.

 

[MisterB]

+1 for drilling holes into the mounts to allow for 'mushrooming' ,- but even that isn't much use if you can't adhere to the roof itself.

I check my abs mounts a couple of times a year, by climbing up stepladders next to the motorhome and giving the panels a vigorous shake. so far it's the whole motorhome that moves, not the panels on their own.

Sorry just reread your message my panels are mechanically secured to the abs brackets, not glued.

I use self tapping roofing screws AND nuts and bolts to fix the panels to the mounts

 

[Rohsman]

It's best to mask off the roof area where the mounts are to go and roughen the intended fixing surfaces with emery to remove the gel coat.plus roughen the plastic mounts or even drill the underside to create several holes to allow the sika flex to go through. Not sure if acetone is the best thing to use as this may soften any paint etc and mat affect the plastic mounts. Simplex sell a cleaning agent and activator which would be better than acetone imo.
When applying the sikaflex use tile spacers or matchsticks to create a layer of sikaflex between the mounts and roof rather than squeezing it all out.

Thanks for advice, I had picked up on this from previous threads and used tile spacers to space mounts to panel. I think the acetone reacted with ABS and leached some plasticiser out of the surface which then made the bond fail. Luckily hadn’t mounted panel on roof!

We're you using the correct Stika as a lot are not suitable for plastic.

Bin the abs mounts and use aluminum they rarely ever fail.

I don’t know why manufacturers recommend ABS mounts I would have chosen aluminium. Maybe they cope better with flex of motorhome roof and body on a large vehicle? Adhesives are great but surface preparation is very important and advice inconsistent on acetone / spirit / meths / isopropanol etc

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[Guigsy]

I didn't have issues with my previous 280w panel that was Sika'd to the roof with plastic brackets. I did bolt the brackets to the panel though. I also used alcohol to wipe the surfaces down. Acetone actually dissolves ABS. It soaks into it and softens it. Probably not a good combo.

 

[Rohsman]

+1 for drilling holes into the mounts to allow for 'mushrooming' ,- but even that isn't much use if you can't adhere to the roof itself.

I check my abs mounts a couple of times a year, by climbing up stepladders next to the motorhome and giving the panels a vigorous shake. so far it's the whole motorhome that moves, not the panels on their own.

Sorry just reread your message my panels are mechanically secured to the abs brackets, not glued.

I use self tapping roofing screws AND nuts and bolts to fix the panels to the mounts

Thanks for reply. Mounts not cleaned with acetone seem to have bonded well, but will still add screws on mounts to panel. Surprised how long it took Sikaflex 252 to really go off. Bonding to roof has no room for error so glad of learning experience with mounts!

 

[Rohsman]

I didn't have issues with my previous 280w panel that was Sika'd to the roof with plastic brackets. I did bolt the brackets to the panel though. I also used alcohol to wipe the surfaces down. Acetone actually dissolves ABS. It soaks into it and softens it. Probably not a good combo.

Yes Acetone / ABS not a good match but great on aluminium/GRP and what I had to hand. Only used on one mount as it seemed to react. Alcohol must be the answer! Though not till the suns over the yard arm.