Roof Top Solar

I'm about to add 400 watts of solar to ensure I can run refrigerator in 12v while driving. Can someone tell me the thickness of the roof for screw size?

I SEEM to remember my roof being about 3/8" plywood when I installed my Fan-Tastic fan many, many years ago. But, I don't know the thickness for sure.

If you look online, you'll see there are other ways to install panels rather than drilling holes in the roof. One of the best methods I've seen is by "Tito" and this is the link: He used flexible panels in one of the threads he posted, which is what I used in my installation, and VHB tape to hold them in place. My installation, which happened earlier than Tito's used Eternabond tape and my thread on it is here:https://www.hilotrailerforum.com/f28/my-new-200-watt-solar-installation-now-300-watts-4354/ It's worked fine.

I did not trust the roof to hold the panels in place with any kind of screws and I did not want the added weight of rigid panels so I went with the flexible ones at 4# each. Our trailers have the added complication of getting the wiring down to the batteries, through the telescoping top, and my thread shows how I did that.

- Jack

Thanks, Jack. I'm not too concerned right now about an extra 75lbs so I'm going to use hard panels. I will run the wires externally to a secondary controller that I will install in the battery box. Most of the weight will be for a 2-battery solar generator power station I'm building
in the back of my truck with a 100 watt panel mounted on the tonneau. When parked for boondocks, I will parallel all three batteries for a 300 Amp system with 500 watts of solar. Not enough to run the a/c but enough to run anything during the day and lights/tv/radio in the evening. The 3/8ths info is helpful as I will use thick but short screws and butyl tape, as well as, rubber sealant over that to make up the strength difference.
Re: Jay

Jay, hard panels are fine, but if I were you, I'd pull the fan off the roof to check the actual thickness of the roof if I was mounting them with screws. My memory could be faulty regarding that thickness. It was a long time ago that I put in the fan, maybe 2009?

I know I did not feel comfortable using screws at all in my setup. If I could have used bolts with fender washers on the side where the nuts would go, that would have been fine, but I didn't want to muck up the ceiling to install them that way. The wood just seems too thin (to me) for good purchase using screws.

- Jack

Also, as a workaround to pulling the actual fan, you may be able to pull the garnish moldings inside and see the thickness of the roof without having to pull and re-seal the fan from the top. Just a thought.

Yes, thankee y'all. I will do a thorough inspection before actually "screwing things down."