Running wires in from solar panels

[Cubey]

I am going to soon be adding one or two solar panels to my Class B. It lacks any appliance roof vents like it seems many people run wires in from... so I am figuring I will have to just drill through the roof to run in the wires. There's reallly no other choice, short of running about 4x as much wire to my roof vent, drilling through it's side edge, putting a grommet and hoping it doesn't leak.

My idea is this:

- Drill a hole through the roof/ceiling for the wires (big enough for a piece of hose for conduit to house the wires inside)

- Put an outdoor gang box over the newly drilled hole with butyl tape around the bottom, screw it down to the roof and seal around it with RV caulking. (A foam seal and matching cover will go over it to seal it)

- Run the wires into the gang box from the panels, splice them there, and then run the wire inside

- Inside of the van, house the wires inside of self-stick wire covers to contain the two wires and make it look better, run it a very short way to where the charge controller will be (in the upper cabinet next to the 120v breakers), then run the wires down to the batteries.

I intend to use 8 gauge wire and it should be less than 15ft so with at most 200w of solar I plan to install, the wire will be plenty large enough to carry the amps without loss. 10 gauge might be within specs but it's better to go a bit larger since it's not that expensive.

If anyone has any better ideas for running the wires in, I'd like to hear it. The roof edge is rounded. I considered mounting a gang box on the side of the rounded area but it might not seal up too well... and it would look weird having a gang box on the upper side of the van like that. If I mount it flat on the roof, it won't be as bad.

[Doggy Daddy]

I recommend you contact the guys at AM Solar.
They are friendly and helpful.
Welcome to AM Solar_Your RV Solar Specialists since 1987

[Shadowcatche]

There are water proof electrical connectors but difficult to find in larger wire gauges. Since I have a high voltage panel I was able to use 10 ga wire with no fear of voltage drop and used a Perko waterproof marine plug. Your plan sound do-able however.

[LEMO]

Another option is to open some panels to find where your plumbing vent stack(s) come down. You might be able to drill into it then fish the wiring down and out the vent, seal your hole then continue the wiring toward your regulator/house batteries. This could save you from cutting into the roof.
Good luck.

[Cubey]

There are no external plumbing vents. It uses air admittance valves within the living space.

[vsheetz]

Roof C-Box | Combiner Boxes

[Cubey]

$80 for a 3" x 4" hunk of plastic? I don't think so. That is for 500w to 1000w systems anyway. I'm looking at a 200w max system here, as previously mentioned.

Besides, I'd still have to drill through the roof and install that $80 piece of crap in the way I described in my original post. I can do it for about 1/8 the cost with a regular outdoor gang box.

[vsheetz]

Originally Posted by Cubey

$80 for a 3" x 4" hunk of plastic? I don't think so. That is for 500w to 1000w systems anyway. I'm looking at a 200w max system here, as previously mentioned.

Besides, I'd still have to drill through the roof and install that $80 piece of crap in the way I described in my original post. I can do it for about 1/8 the cost with a regular outdoor gang box.

Offered it as an option or idea stimulator, sorry I wasted our time...

[TechWriter]

Originally Posted by Cubey

. . . Put an outdoor gang box over the newly drilled hole with butyl tape around the bottom, screw it down to the roof and seal around it with RV caulking. (A foam seal and matching cover will go over it to seal it).

Instead of combining wires above, combine them below at the solar controller (parallel wiring).

Then use one of these Winegard surface wiring panels:
SwidenOnline.com offers Winegard cable entry plate CE4000

[elkhornsun]

I would combine the wires from the two panels under one of the panels that is nearest where you want to make the roof penetration and have that penetration under the panel. If the run from the panels to the charge controller is less than 20 feet you should be fine with 10ga wire. AMsolar.com is a good place to buy a length of double wire 10ga that has a single outer sheath.

For running the cable to the inside of the RV I would use a Blue Sea cable clam which is a type of cable gland that works very well. An alternative is to use the Instapark IN-SW surface mount gland which come in a models for either a single or two cables up to 12mm in diameter. The Blue Sea cable clam is easy to attach to the roof. The Instapark require the use of some Eternabond tape to keep them securely in place as there are no flanges that could be screwed to the roof. Instapark are sold on Amazon. The Blue Sea cable clams are sold at many marine supply places including West Marine.

Cable size recommendations are usually overkill and based on a maximum 3% current loss from the panels. Going down a size will result in "only" 90% of the output getting to the controller but it can make the wiring infinitely simpler to do.

[Cubey]

Originally Posted by TechWriter

Instead of combining wires above, combine them below at the solar controller (parallel wiring).

Then use one of these Winegard surface wiring panels:
SwidenOnline.com offers Winegard cable entry plate CE4000

Hmm.. will that work on a roof without leaking? I wish I could see what the back side looks like. I guess if you install it with butyl tape on the bottom then caulk around it, it wouldn't leak.

I'd rather do 8 gauge and have as much charge capability as possible... since we're talking a 200w system which is probably what I'm gonna do. Why do the work twice to add more if I find 100w not enough? 40 feet of 8 gauge wire (20ft each of red and black) is under $20 on ebay so... heck yeah... Why try to save $10 on a $350+ solar system and risk having it perform less than at full capacity.

I might decide later to add another 50w panel. It would suck to have to go back and rewire it because I wanted to save a few bucks now.

I will look into those other suggestion fittings.

[Pigman1]

I used a 5x5 outdoor plastic box on the roof. Panel wires ran to it and a conduit straight down from the bottom of the box to the inside. The box was sealed to the roof over the penetrating roof hole. I used mini fuses in the box so I could cut off individual panels (we have 4 140w panels). The box is easy to seal and easy to seal to the roof. About $6 at Lowes as I recall. If you don't want to use split bolts or wire nuts to consolidate the circuits, you can use short aux ground bars in the box. Also available at Lowes.

[Luv2go]

Here's a blog entry for someone who did this on his class B. Hope it gives you some ideas.

[Cubey]

Originally Posted by Pigman1

I used a 5x5 outdoor plastic box on the roof. Panel wires ran to it and a conduit straight down from the bottom of the box to the inside. The box was sealed to the roof over the penetrating roof hole. I used mini fuses in the box so I could cut off individual panels (we have 4 140w panels). The box is easy to seal and easy to seal to the roof. About $6 at Lowes as I recall. If you don't want to use split bolts or wire nuts to consolidate the circuits, you can use short aux ground bars in the box. Also available at Lowes.

Yeah, that's about what my idea is to use a gang box. Common, cheap part but made to be weatherproof for 120v outdoors, so safe for 18v coming from the panels. I'll just have to try to hide the wires in plain sight inside since there's a large curve to the roof at the edges, and I would have to either run the wires from out in the open... or mount the box on the curve and have it look really tacky.

So one way makes it look funky inside, one way makes it look a tiny bit funkyoutside. That's really my only two options. unfortunately. Inside is better since it'll be much less visible, 2 wires hidden inside of a wire concealer running about 2 feet along the ceiling over one of the dinette seats, right up against a wall so it won't ever get bumped into. Then it enters the cabinet and will be concealed from there. Then one more concealed wire track down to the batteries in the corner there for the 4 wires from the solar charge controller down to the batteries.

Originally Posted by Luv2go

Here's a blog entry for someone who did this on his class B. Hope it gives you some ideas.

Eeek... he just ran the wires in a hole and caulked the hell out of it.