Drilling holes in the roof to mount solar panels

[jimmoore13]

For my PUP, I called Forrest River and asked about wiring. In my case, the tech person said that all wires run longitudinally along the road-side edge of the roof then are routed to the light fixtures and AC unit at a 90 degree angle to the side wall. I installed my panel straddling a light fixture and encountered no wires.

I don't know your rig, but if you have AC ducting in the Styrofoam, the tech person an help you avoid that space, too.

Reach out to Kathy and ask her to connect you to the right person:
KATHY SWOPE
ROCKWOOD and FLAGSTAFF TENT CAMPER PARTS
KSWOPE@FORESTRIVERINC.COM
PHONE # 574-642-8927
FAX # 574-970-7973
Just be clear that you are looking for an introduction to the right person. She has been VERY helpful.

My roof is very light weight. Very thin fiberglass, 1/16" to 1/8" plywood, 3/4" wood framing, light plywood, and ceiling finish. Total thickness 1". I used stainless 1/4" thru bolts and fender washers inside along with nylock nuts. To avoid compressing the roof sandwich, I selected bolts with a solid shank just the right length, and then I stacked the fender washer and one or two smaller washers so that I could tighten the nut all the way to the shank while just slightly squeezing the roof sandwich. Worked like a charm. Again, no problem with wiring.

I filled the screw hole hole and the joint between the panel bracket and the roof with silicone caulk/adhesive, then dabbed more on top of the screw/bolt head. That held up well...3 seasons so far with no additional sealant required.

With wood screws, I'd suggest first injecting the hole with Gorilla glue to hold the screw from backing out. Then add the silicone seal above the glue.

You might wish to consider using stainless "deep-thread" screws: https://www.fastenersuperstore.com/s...p+thread+screw
The roof plywood is likely to be plywood sheathing...a poor grade of plywood. The deep threads will get a slightly better bite into the material. And stainless is both compatible with aluminum (brackets) and won't rust and stain your roof.

Good luck with your project.

[larry2c]

Thanks for the tips Jim - I had noticed a lot of the screws in our trailer were "different" than normal screws (not just the square drive but the threads) but I'd never heard of deep thread screws before. I'll look into those to see if they'd be better than what came with the mounting brackets.

[Comanchecreek]

How did you route your wiring? How do you get from the roof down to the batteries? That, to me, seems like the most difficult part of any installation. Even once you get inside you have to get through the living space to the underside of the trailer, into the battery compartment.

[larry2c]

Originally Posted by Comanchecreek

How did you route your wiring? How do you get from the roof down to the batteries? That, to me, seems like the most difficult part of any installation. Even once you get inside you have to get through the living space to the underside of the trailer, into the battery compartment.

I will be posting some pics once I get it all done but here's the short story without pictures. The two 100W panels are aft of the AC unit and one on each side of the center line of the trailer. the wires run from the panels on top of the roof to the refrigerator vent corridor (don't know a better name for that). The base of the fridge sits on top of a void where the WFCO power panel is mounted so I pass the wires through that void and out the bottom of the trailer next to the outer side of the frame rail. The wires run along the frame rail to the front of the trailer and then back thru the floor at the front wall of the trailer which is in my pass thru. I created a panel with the charge controller, disconnect switch and fuse mounted to it which is then attached to the 1X at the front top of the pass thru. That's only 2 feet from may batteries so getting connected there was easy.

Like I mentioned, I'll do a write up with pictures when I'm done but if you have any questions in the meantime, let me know. People on this forum have helped me a lot so I am happy to give a little back!

[larry2c]

In the post above I mentioned that I will be routing the cables from the PV panels across the roof to the refrigerator vent corridor. I am thinking once I have everything stretched out properly, I could place a couple 6" lengths of Eternabond over the wires in a couple places to hold them from flapping around. Is that a good idea or?

[babock]

Originally Posted by larry2c

In the post above I mentioned that I will be routing the cables from the PV panels across the roof to the refrigerator vent corridor. I am thinking once I have everything stretched out properly, I could place a couple 6" lengths of Eternabond over the wires in a couple places to hold them from flapping around. Is that a good idea or?

Yes...or a blob of dicor. BTW, I personally like the non leveling dicor for this and the mounts. Tends to stay thicker covering the screws.I started with self leveling and switched it up by the end

[jimmoore13]

Originally Posted by Comanchecreek

How did you route your wiring? How do you get from the roof down to the batteries? That, to me, seems like the most difficult part of any installation. Even once you get inside you have to get through the living space to the underside of the trailer, into the battery compartment.

The thing you're looking for is a "gland." It's possible to mount them on the roof and seal them well, but my preference is to run the wires to the very top of the side wall, mount the gland there...aligned with an interior cabinet to hide the wires and create a place to mount the solar charge controller. Water-proofing on the fiberglass side wall is easier than on the roof, and the wire entry points on the gland can point down at the ground further ensuring a dry fit.

Use the term "gland" to search for what you are looking for.

[babock]

Originally Posted by jimmoore13

The thing you're looking for is a "gland." It's possible to mount them on the roof and seal them well, but my preference is to run the wires to the very top of the side wall, mount the gland there...aligned with an interior cabinet to hide the wires and create a place to mount the solar charge controller. Water-proofing on the fiberglass side wall is easier than on the roof, and the wire entry points on the gland can point down at the ground further ensuring a dry fit.

Use the term "gland" to search for what you are looking for.

This is what I use. I went down an interior chamber that was right next to my entertainment center. For me, running it down the refrigerator vent would have doubled my wiring distance.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

[larry2c]

Originally Posted by babock

Yes...or a blob of dicor. BTW, I personally like the non leveling dicor for this and the mounts. Tends to stay thicker covering the screws.I started with self leveling and switched it up by the end

Thanks for the tip and the pictures - your install looks great!

[Philkaty]

Originally Posted by A32Deuce

I didn't even try or kill for them. I read where someone else did how I did it. I try picking up on them anytime I'm on the roof and no movement. Dicor acts like a glue. I did drill a small starter hole first by wrapping tape around the bit leaving 3/4 showing.

Since I got a fiberglass roof, is there a need to pre-drill? Thanks

[A32Deuce]

I have a fiberglass roof and did drill a small starter hole. Makes it easier to screw in and doesn't hurt anything.

[larry2c]

Originally Posted by babock

Yes...or a blob of dicor. BTW, I personally like the non leveling dicor for this and the mounts. Tends to stay thicker covering the screws.I started with self leveling and switched it up by the end

One more question on the Dicor application. How did you get the back of the mounting brackets with the Dicor since it is under the panel?

[babock]

Originally Posted by larry2c

One more question on the Dicor application. How did you get the back of the mounting brackets with the Dicor since it is under the panel?

I first put a layer of Dicor down before I screwed down the brackets. Also, hard to tell but the brackets are pretty tall so I can apply Dicor after screwed down too. Bracket height is 2.5". back edge of the bracket is even with the side of the panel too.

[larry2c]

I see I'm not the only person that made custom brackets!

Thanks for the picture and info!

[Richard W Eason]

The panels will likely have a much higher voltage to the controller than from the controlor to the batteries. My four panels' wires operate at ~175 volts, while the battery wires operate at ~13-14 volts. Use much larger wires on the low voltage side, and minimize that distance to reduce voltage loss on the way to the battery.

[larry2c]

Originally Posted by Richard W Eason

The panels will likely have a much higher voltage to the controller than from the controlor to the batteries. My four panels' wires operate at ~175 volts, while the battery wires operate at ~13-14 volts. Use much larger wires on the low voltage side, and minimize that distance to reduce voltage loss on the way to the battery.

Thanks Richard - so far with my two 100W panels I've only seen about 16+ volts and if I remember right, my CC has a max input of 24V. My batteries are only about 2' from where the CC is located and I've run 8 AWG wire from the panels to the CC and from the CC to the batteries.

[babock]

Originally Posted by larry2c

Thanks Richard - so far with my two 100W panels I've only seen about 16+ volts and if I remember right, my CC has a max input of 24V. My batteries are only about 2' from where the CC is located and I've run 8 AWG wire from the panels to the CC and from the CC to the batteries.

Looks you bought those 100W Renogy low volt 100W panels. Not even sure they were still selling those. Hopefully, you are putting them in series if you are using an MPPT. If they are PWM, it doesn't matter since anything over 14.4V is pretty much waste energy anyway.

[larry2c]

Parallel and PWM. The panels are advertised as "new edition" and they have a slightly greater output than the previous model

[babock]

Originally Posted by larry2c

Parallel and PWM. The panels are advertised as "new edition" and they have a slightly greater output than the previous model

What are the specs? Have the link?



Since you have PWM, it doesn't matter what the voltage output is as long as its higher than battery voltage. For people with MPPT that put those lower 18V panels in parallel, they are fighting a losing battle. Of course putting panels only in parallel is a waste in an MPPT system. If you ever go MPPT in the future, put them in series.


EDIT: I see the specs now. Operating voltage is 16.4V. Like I said fine for PWM...not so great for MPPT.

[larry2c]

Yeah, this was a solar on a budget project. I think for the money spent it will do fine for what we need. I may add another panel and mount it with a pole mount that could go on the front A frame or back bumper. This would allow me to position the panels properly. As I was installing these panels I did an experiment where I tilted the panel up to roughly match my stick house panels. That bumped the output up about 25%...