Planning out my solar system and I see most go thru the fridge vent. Are you drilling a hole from the side and running cable down shaft or using fittings? I read that you stay on opposite side of flue.

I had to go through a screen on the fridge flu to gain access when I ran two RG cables down through for SAT TV...I guess I didn't seal it too good as now I get the LADY BUGS in the fall part of the season in my air conditioner ducts that run thru the ceiling area...Everything works fine just be sure to seal up any holes you make good...Roy Ken

An alternative: fridge vent combiner box

Open the vent - remove that big plastic cover. Then you will have a better picture. There is no "shaft" in my trailer. Under the cover you will find a plastic coaming with mesh on top, about 2" tall. Under this coaming there is a fridge cabinet.It's difficult to use a normal strain-relief fitting without having access to both sides of the fitting. I had to cut the mesh a little, to access the fitting on the inner side of the coaming. Some other people cut the fitting flash with the coaming and glued it to the coaming from outside. If you you attach the cable to the roof with a caulk before the vent, and then with a spray foam or caulk on the other side - where it exits through the fridge cabinet wall - you don't need to worry about fixing it in the coaming.Once inside the coaming, my cable exits right through the fridge cabinet wall to kitchen (there was some wigging with a coat hanger wire to route the cable through that wall, while sitting on the roof). I used a spray foam in that hole in the wall. On the other side of the wall there is (usually) some cabinet.I didn't use fridge vent combiner box for these reasons:1) This box is expensive and bulky, it doesn't fit under the plastic cover well.2) I didn't need all those many fittings because I used series wired panels, so there was no cables to "combine" and therefore no need in "Combiner box".

Fisherguy made a neat job of his with a photo if it can be found.https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28531332/srt/pa/pging/1/page/1.cfm

Because I have so many panels, I installed a J Box on the roof in a pool of Dicor, then drilled a diagonal hole into the left, non flu side of the fridge cavity. This was an early pic with only two panels installed.

Solar cable thru fridge vent | Good Sam Community

bigfootford
Nomad II
Dec 18, 2015
Here is what I did, 2 ea 100watt panels:

10 ga from each panel into Jbox. 10 ga for each panel into fridge rear access. Used electrical ground bar to combine panel power leads into 1 8ga wire each for + and - to my Solar controller.
Almot
Explorer III
Dec 18, 2015
Something I don't understand with this V-drop calculators. The one in BFL link says "single set of conductors, one-way length". If we have 2 leads of the same length, all is good. And, in panel wires this is usually the case - same or close length of Pos and Neg from panel to controller.

But, lets consider Pos 30ft and Neg 1 ft - ex, you bolted Neg to the frame when doing some trailer wiring - not necessarily panels. Should we still use one-way length, and if so, which one - 30ft or 1 ft? :)
Almot
Explorer III
Dec 18, 2015
DAS26miles wrote:
Question, what are maximum amps and length for 10 and 12 awg with 5% loss for 12 volt ?
Can you use 12 awg directly from panels to branches 5 feet away and then use 10 awg to the controller?

Your max amps will be shown on the panel specs. For PWM controller - you didn't specify but I assume that it's PWM - you use panel Isc for amps. The "ampacity" of #10 wire - max amps it can conduct safely - is 30A, as I recall.

Use V-drop calculator separately for #12 pigtail and #10 extension cable, the one in my link or any other similar calculator. Add both V-drop numbers.

Yes, you can use #12 pigtail with #10 extension if total V-drop is within the norm. All panels come with #12 pigtail (if there is a pigtail), even big 280W panels.

You CAN have #8 extension cable if you have to. Unlimited Solar have it, good quality and reasonable cost. It's recommended to stay within 2-3% V-drop, but, like I said, PWM and MPPT have different requirements and you didn't say what controller. Or - what panel(s).

To avoid pains of thick cable, there is an option to go series connection and MPPT controller. Especially if total panels area is over 180W-200W.
BFL13
Explorer II
Dec 18, 2015
This one is very clear on one-way vs round trip

http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=2.061&voltage=12&phase=dc&noofconductor=1&distance=60&distanceunit=feet&amperes=8&x=42&y=5
Almot
Explorer III
Dec 18, 2015
CJW8 wrote:
Remember to use round trip length on the calculator length posted above.

Nope. A single trip length. There are other similar calculators to verify, most of them use single-trip. Compare Southwire (in my link) to the one in BFL link (this one does specify single-trip), both provide same results.
DAS26miles
Explorer II
Dec 18, 2015
It's going to be 5 feet from panel to fridge vent and branch, then another 15 to 20 feet to controller. So maybe 5 feet of 12 awg and the rest 10 awg
DAS26miles
Explorer II
Dec 18, 2015
Question, what are maximum amps and length for 10 and 12 awg with 5% loss for 12 volt ?
Can you use 12 awg directly from panels to branches 5 feet away and then use 10 awg to the controller?
CJW8
Explorer
Dec 18, 2015
I think your wire is too small. Especially if you are going to use the whole 60 feet + the pig tails on your panel. Remember to use round trip length on the calculator length posted above.
KRumm
Explorer
Dec 18, 2015
Here is a relatively low impact installation (I assume he reinstalled the mesh after wiring)

I would have also wired the panels in series (No combiner box) and used lower 10 gauge wire...
time2roll
Nomad
Dec 18, 2015
Very small cut to direct the wire down.