Wiring for a solar installation - how big does it need to be? - RV-Dreams Community Forum

Sherry · RV-Dreams Family Member

Wiring for a solar installation - how big does it need to be?

Alie and Jims Carrilite · RV-Dreams Family Member

The lower the gauge number, the bigger the wire, the less voltage drop you will have going from the combiner box on your roof to your controller. Same with the wire from the controller thru all the "stuff" to the batteries. The length of the wire also dictates the size, the longer the run, the bigger the wire. There are amperage wiring size charts available.

Found this little tool. Plug in the numbers you have, including the estimated length of the wire routing and it will show what the loss is. Then you can decide if 10 is acceptable or if 6 might be better.

http://www.genuinedealz.com/voltage-drop-calculator

-- Edited by Alie and Jims Carrilite on Saturday 1st of March 2014 09:39:10 PM

Lonney Wade · RV-Dreams Family Member

When they install all the solar panels and all wires come together to the combiner box 2 wires will come out, one positive and one negative, that is where the larger wire come in to play.

Not so much how big the wires are but how much amps they can carry, if you would like the very best wire and very flexible, 4 AWG wire at 140 amps with 1045 strands of wire in it would be a nice wire to use, the finer the wire with more copper wire in it, the more amps it can carry and the thicker cable jacket is orange in color. It can handle more amps than the thinner black jacket 4 AWG wire that carries 100 amps and has 374 strands of wire and not as flexible, here is the wire Co.

http://www.wireandcabletogo.com/WeldingCable/

(and here is the wire I was talking about)
http://www.wireandcabletogo.com/4-AWG-Welding-Cable-Class-M-UL-CSA.html

I use this type of wire but it's 2/0 gauge with 3300 strands of wire and can carry 300 amps on 7 batteries total.

Lonney

-- Edited by Lonney Wade on Sunday 2nd of March 2014 02:24:32 AM

Jack Mayer · RV-Dreams Family Member

Find a new installer. Anyone recommending 10 gauge is not someone I'd use UNLESS the run is very short and high voltage. It is easy to figure yourself and there is no "discussion"....there is a right answer and it is based in physics - not opinion. Let me be clear - #10 is only going to be the right answer in less than 2% of the cases.....and that would be on very small rigs - not the rig you have in your sig. line.

Run one of the voltage calculators. Use the Vmp and Isc of the panels - depending on how they are wired these may have to be calculated. DO NOT use 12 volts.

If you have difficulty with this and want me to do it for you just email me the info, or post here....we are in transit today, but I can get it done tonight or early tomorrow.

Based on the info you provided so far I would be VERY VERY suspicious of this installer.