Locating roof crossbeams for solar panel install?

I tend to agree with Fiverwheel, except that I think there would be less flexing if you aim for the roof trusses. Flexing is not necessarily bad but could hasten a leak scenario. I bet your 2003 Prowler is built similar to my 2004 Pioneer, which means they're every 16" on center. As previously mentioned by dockmasterdave, you can easily feel where the wood cross members are. I also think I successfully used a stud finder.

I have had three RV's with solar. Not one of them ever lost a panel due to wind load. Try not to overthink the project...the screws will work just fine. Be sure to seal the brackets after installing.

I decided not to mess with the roof here in my planning... I am really thinking hard about running two ALUMINUM UNISTRUT strips across my POPUP roof and using some side mounting pieces attaching this to the side of the trailer up high next to the roof. The UNISTRUT will allow me to use the Z angle mounts on the panels and mount to the sliding center nut on the UNISTRUT...


If I can't come up with side mount angles then drilling into the metal rails at the edge of the roof should suffice like shown in the GOOGLE PHOTO...





If I think I will need to add some center support I will just glue some in place in the center of the roof...

With the lightweight ALUMINUM UNISTRUT all the way across the roof area will allow you to add more panels later on with ease...

Just another idea for you to consider perhaps. I just don't want to do anything bad to my thin roof.

'Food for thought'
Roy Ken

Use a stud finder.

Bruce

Can you just lightly push up on the inside of the ceiling to find the rafters, then measure to a thru roof opening, like roof vent or AC?