Solar panel set up wire size required

[Fatboyz]

I'm getting ready to plumb my truck as I'm insulating the roof. I have 3-100 Watt panels that are rated for 5.8 amps each in ideal conditions. So realistically about 12-15 amps total. What gauge of wire should I run from the panels to the controller?
Second question, anyone have a recommendation for a plug/fitting to go through the roof for the wires?
Thanks

 

[luthj]

Are the panels parallel or series? Are they permanent mount? Or do you anticipate removing them on occasion?

What is the total length of the wire run from panels to controller? (pos and negative)

MPPT or PWM?

 

[Fatboyz]

Panels are permanently mounted to roof. Wire run will be about 12' max. Controller is PWM (haven't bought it yet, but locally available for reasonable. Sunforce/coleman 30 Amp controller.

 

[luthj]

With a 3% drop at 15A, and a 12ft (total wire length) run, 12 gauge will do the trick.

More important is that the voltage drop between the controller and battery is 1% or less at your arrays nominal output. This will ensure the batteries actually see the correct voltage.

I did a search on that controller, and I could not find its actual charging voltages. That does not bode well. If you cannot match (or program) to your batteries needs, the controller is worse than worthless, it may ruin good batteries in short order.

Of the shelf most inexpensive solar controllers are configured to undercharge batteries (slowly killing them).

 

[john61ct]

10 AWG

Victron SmartSolar MPPT 75/15 maybe $120, or 100/20 if you don't want to over panel

Locate the SC right at the bank.

Google "wire clams, Blue Sea is good.

 

[Fatboyz]

sounds good. Thanks for the info. will look into those controllers. Want to run wire prior to spray foam insulation.

 

[Fatboyz]

I found a 100/20 Victron on Amazon for 158.00 Canadian. Looking at the specs it will handle up to 20amps, but it says max 290 watts. Will I still be ok with my 3-100 watt panels?

 

[luthj]

Yes.

 

[john61ct]

Yes, can overpanel ampacity by a lot with Victron, that is the **output** limitation into a 12V bank.

Your panels will only very occasionally touch their rated max anyway.

 

[FlipperFla]

I'm getting ready to plumb my truck as I'm insulating the roof. I have 3-100 Watt panels that are rated for 5.8 amps each in ideal conditions. So realistically about 12-15 amps total. What gauge of wire should I run from the panels to the controller?
Second question, anyone have a recommendation for a plug/fitting to go through the roof for the wires?
Thanks

Do a google search “wire size chart” it will tell you what gauge wire for length of run and current. Blue Seas website also has the chart

 

[ArkansasDon]

I run 20ft 10awg cable to my panels. I run 2 100 watt Renogy portable suit case w\ branch connector with a 5 ft. pig tail to the 2nd panel "if" I'm running them parallel or I can just run a single 100 watt & 30 amp Renogy Wanderer Charge Controller w\ Battery Temperature Sensor. I talked with Renogy on the phone explaining the use of solar & what gear & data of each piece of 12v. gear I plan to use: amps, how long each piece will be in use: if its continuous use or on demand. They came up with a reliable fail safe system for me. I have way enough power w\a great reserve.