Need help putting Renogy solar panel on roof on Grand Design 5th wheel using zclamps

[hylasw]

I have a Brand New 2023 Grand Design 150 series 290RL Model 5th wheel currently their is a factory installed Furion 165 watt Panel on the front passenger side of camper it appears they used z clamps (looks like Renogy Z clamps) to install them into the roof. I want to install another 175 watt panel on the drivers side using Renogy Z clamps my questions is what screws do I use what length ? The Renogy z Clamps come with 1 1/2 inch screws which camping world told me that is to long they told me that only use a max of 3/4 inch screw is that true ? Also what type of screw ? The tech at camping world told me that self tapping screws are to hard on the roof and wont sink in ?
Please help !

 

[SamDeleted]

I'm not familiar with that camper

What's the roof made off, how thick is it? Any photos ?

Make sure your screws are outdoor rated , possibly coated

 

[littleharbor2]

When you do mount the panel you should thoroughly scuff and clean the area under the mounting point then use some 3M 5200 adhesive. 5200 is a super strong product that grabs so well you can remove the screws and would really have to work to separate the brackets from the roof.

 

[Aussieguy]

remove one of the screws already used

you will need to seal all the screws on the new panel
therefore doing one more won't be an issue