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Open Roads Forum  >  Travel Trailers  >  Modifications and Accessories

 > Routing Solar Wiring from Roof to Pass Through Storage

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crcr

US

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Posted: 11/28/19 10:08am Link  |  Quote  |  Print  |  Notify Moderator

I'm about ready to install a solar system on our 28' 2011 Jayco TT. Solar panels will be on the roof with the wires from each going to a roof combiner box, then a pair of wires from the roof combiner box going down to the pass through storage, where my solar controller, inverter, etc, will be mounted on a piece of 3/4" plywood opposite the two 6V batteries on the tongue.

To minimize voltage loss, I want to route the wires from the roof combiner box, which will be in the center of the roof at the front of the TT, to the solar controller in the pass thru storage via the shortest possible distance. The shortest route is down through the front center of the TT, between the front cap and the paneling on the inside wall. In the pic below, you can see the inside wall. I removed the decorative headboard which is held by 3 screws, and behind that is the same paneling.

I don't know for sure what is behind that paneling. I recently drilled a hole for another project in the rear wall of the TT, and the insulation there was solid styrofoam. Should I expect that the insulation between the front cap and the inside paneling is also styrofoam? Or would it likely be a different material?

If it is styrofoam, any suggestions on the best way to route a wire from the roof down through it? I can take my oscillating multi-tool and from the inside cut one or more access openings into the front wall, behind where the decorative headboard fastens. For obvious aesthetic reasons, I don't want to cut any access openings into the paneling above the headboard. If the insulation is styrofoam, I wonder how hard it would be to get a wire from the roof through the styrofoam and down to the pass through storage. Does anyone have any experience with a similar project?

Thanks for any tips and suggestions!

[image]

2oldman

Ca

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Posted: 11/28/19 10:10am Link  |  Quote  |  Print  |  Notify Moderator

crcr wrote:

To minimize voltage loss, I want to route the wires from the roof combiner box, which will be in the center of the roof at the front of the TT, to the solar controller in the pass thru storage via the shortest possible distance.
You can minimize V loss, and ditch the combiner box by wiring in series.

crcr

US

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Posted: 11/28/19 10:15am Link  |  Quote  |  Print  |  Notify Moderator

2oldman wrote:

crcr wrote:

To minimize voltage loss, I want to route the wires from the roof combiner box, which will be in the center of the roof at the front of the TT, to the solar controller in the pass thru storage via the shortest possible distance.
You can minimize V loss, and ditch the combiner box by wiring in series.


Thanks, but I have studied this and have already made the decision that I will be wiring in parallel, and I will use substantial gauge wire from the roof combiner box to the solar controller. Parallel wiring because we camp in Forest Service campgrounds and state park campgrounds, and very often during the day, parts of the roof will be shaded, and parts will not. By wiring in parallel, if one or more solar panels has it's output cut drastically by shading, and other solar panels are still in full sun, I will still get a decent amount of amps.

pianotuna

Regina, SK, Canada

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Posted: 11/28/19 11:44am Link  |  Quote  |  Print  |  Notify Moderator

How many watts of panels? What controller? How thick is "substantial"?


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

opnspaces

San Diego Ca

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Posted: 11/28/19 11:47am Link  |  Quote  |  Print  |  Notify Moderator

Unfortunately I'm going to bet your front wall is the same Styrofoam as the rear making it impossible to just push a wire through. What gauge wiring are you running down the wall? Can you hide it on the surface behind some white or tan channeling?
Link

It looks like you have cabinets on either side of the trailer that comes down most of the front wall. And I'm assuming there's a night stand table feature under the cabinets leaving a gap between the two of about maybe 18 inches. I would take the voltage drop hit and extend the wire over to the drivers side front corner and come down inside the cabinet. Then it's only a short run of visually exposed channel under the cabinet to the night stand and then across to the batteries. I'll bet after a week you wont even notice the channeling unless you actively remind yourself it's there and look at it.

You could even put something in front of the exposed channel like a framed picture of the family or a vase of silk flowers velcroed down so it doesn't move during travel.


2001 Suburban 4x4. 6.0L, 4.10 3/4 ton
2005 Jayco Jay Flight 27BH
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Huntindog

Phoenix AZ

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Posted: 11/28/19 12:25pm Link  |  Quote  |  Print  |  Notify Moderator

This idea may or may not help you:
When I installed my Winegard Traveler satellite dis, the instructions said to route the wiring thru a hole I was to put in the roof... It had some sort of plastic cover to install over it.
I wasn't too keen on that idea. So I opted to run the wires to the back of the TT (only about 4') and down the roof ladder. All the way to the bottom, then thru the underbelly to where I wanted to come up thru the floor with them. It worked great, and will not ever be a roof leak issue.



Huntindog
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2011 Silverado CC DA big dually.



crcr

US

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Posted: 11/28/19 12:50pm Link  |  Quote  |  Print  |  Notify Moderator

opnspaces wrote:

Unfortunately I'm going to bet your front wall is the same Styrofoam as the rear making it impossible to just push a wire through. What gauge wiring are you running down the wall? Can you hide it on the surface behind some white or tan channeling?
Link

It looks like you have cabinets on either side of the trailer that comes down most of the front wall. And I'm assuming there's a night stand table feature under the cabinets leaving a gap between the two of about maybe 18 inches. I would take the voltage drop hit and extend the wire over to the drivers side front corner and come down inside the cabinet. Then it's only a short run of visually exposed channel under the cabinet to the night stand and then across to the batteries. I'll bet after a week you wont even notice the channeling unless you actively remind yourself it's there and look at it.

You could even put something in front of the exposed channel like a framed picture of the family or a vase of silk flowers velcroed down so it doesn't move during travel.


Thanks. Yeah, that is roughly my Plan B. And yes, it may be near to impossible to route a wire down through styrofoam, if that is the insulation. The left and right cabinets are roughly only 12 inches above the built-in nightstands, so yeah, I could route the wire through one of the "wardrobe" cabinets, down into the back of the nightstand, and then into the pass through to the solar controller. As you say, the only place the wire would be exposed is between the wardrobe and the nightstand, at the back, hardly would be noticeable, or I could run it in the corner and cover it with something.

I'll probably run 4 gauge wire down from the roof combiner box. I was going to run 6 gauge, but 4 gauge wire is a bare few pennies more per foot, so I'll just run 4 gauge and have minimal voltage loss.

crcr

US

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Posted: 11/28/19 12:55pm Link  |  Quote  |  Print  |  Notify Moderator

Huntindog wrote:

This idea may or may not help you:
When I installed my Winegard Traveler satellite dis, the instructions said to route the wiring thru a hole I was to put in the roof... It had some sort of plastic cover to install over it.
I wasn't too keen on that idea. So I opted to run the wires to the back of the TT (only about 4') and down the roof ladder. All the way to the bottom, then thru the underbelly to where I wanted to come up thru the floor with them. It worked great, and will not ever be a roof leak issue.


Thanks, but that would be way longer wire run than I want for DC amperage -- too much voltage drop. Re the possibility of the roof leaking, I will use a 4" x 4" x 2" deep plastic gasketed box from HD. I will epoxy two bus bars inside for the wires to all connect. The down wire will go into the roof from the bottom of the box, box will be screwed the the roof and I will seal the bottom of the combiner box with Dicor. Lots and lots of folks install solar roof combiner boxes this way with no leaks.

Lwiddis

Los Angeles area :(

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Posted: 11/28/19 01:04pm Link  |  Quote  |  Print  |  Notify Moderator

“...a short run of visually exposed channel...”

That’s what I did. Appropriately painted or stained no one will notice.


Winnebago 2101DS TT & 2020 Chevy Silverado 1500 LTZ Z71, 300 watts solar-parallel & MPPT, Trojan T-125s. TALL pole for flags. Prefer USFS, COE, BLM, NPS, TVA, USF&WS, state & county camps. Bicyclist! 14 year Army vet - 11B40 then 11A - (MOS 1542 & 1560)


CA Traveler

The Western States

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Posted: 11/28/19 02:31pm Link  |  Quote  |  Print  |  Notify Moderator

I've run wires through styrofoam walls using the common household wire puller to penetrate, pull a string, rope and then wire.

If you are going to use a PWM controller then you don't need the larger wire. PWM controllers use the panel amps so as long as the voltage at the controller is 14.8V or more so larger wire won't help. ie The typical voltage drop from the 12V panels (about 18V) to 14.8V at the controller doesn't get used, just the panel amps.

Serial panels with bypass diodes and MPPT controller are generally more tolerant of shadows than parallel panels.

* This post was edited 11/28/19 02:40pm by CA Traveler *


2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
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2014 Grand Cherokee Overland

Bob


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