8 vs 10 AWG cable for solar install

[transmitterdan]

The decision to run 11A in AWG 8 vs. 10 is purely economic. The system will still function using either
wire. The original poster framed the question as an economic problem and asked if technically there was any risk the system would not work. The answer is it will work with a few hundred millivolt and a couple tens of watts power loss compared to using 10. So the OP knows the trade off and can make their own decision. Sometimes perfection is the enemy of good enough.

[GordMay]

Originally Posted by transmitterdan

... Sometimes perfection is the enemy of good enough.

Indeed.
Voltaire: “The best is the enemy of the good.”
Confucius: "Better a diamond with a flaw than a pebble without."
Shakespeare: “Striving to better, oft we mar what's well.”

Understanding voltage drop, especially in low voltage applications, is good.

[Gustuv Wynd]

Could I ask why you chose to have each panel on a separate charge controller?

Reason why I ask is that I was thinking of expanding the solar on my boat, but I was thinking I'd go for a MPPT charge controller and run the array at a higher voltage so I can use smaller gauge wire (for easier install more than cost, but it would be both...I'd be able to use my existing wires I've excruciatingly managed to get through all the tiny spaces and conduits in my boat). The MPPT charge controller will let me keep the boat side on 12 volts as well so nothing needed to be done there.

The only down side is the MPPT charge controller is more expensive...but actually would probably be cheaper than buying three normal PWM charge controllers and the wiring would be cheaper (even if I wasn't using any existing wiring). I suppose this would also be a single point of failure, but in my case that would be good...I am a river rat who can only dream of his blue water days so I don't have to worry about things like loosing my GPS when I am in the middle of no where. Having one thing to replace can be good some times.

[sailingunity]

My understanding is smaller wire is about the only advantage of running them in series. Obviously more charge controllers means more redundancy, but I've also heard that shading an adjacent panel in series can hurt the output of both panels. Not sure if this is true or not. In my case my existing charge controllers could not handle 400-600 watts if the panels were connected in series anyways. Adding a 3rd charge controller means I can keep the two existing ones.

I did wind up finding 8AWG MC4 connectors, they are only made by multi-connect (not sold on Amazon). The terminal as I've found out is just a generic open barrel crimp, for which I have found an 8AWG crimper for about 30 dollars.

[Gustuv Wynd]

Ahh...didn't realize you were expanding an existing setup.

I am going for series and changing out the charge controller mainly so I don't have to re-run wires...and secure the wires. Uff that was a miserable couple days...

[sailingunity]

Originally Posted by Gustuv Wynd

Ahh...didn't realize you were expanding an existing setup.

I am going for series and changing out the charge controller mainly so I don't have to re-run wires...and secure the wires. Uff that was a miserable couple days...

My boat has pretty good accessibility, the biggest pain will be removing all of the old 14 ga wires from the last solar panels!

[roland stockham]

The only down side is the MPPT charge controller is more expensive...but actually would probably be cheaper than buying three normal PWM charge controllers and the wiring would be cheaper (even if I wasn't using any existing wiring). I suppose this would also be a single point of failure, but in my case that would be good...I am a river rat who can only dream of his blue water days so I don't have to worry about things like loosing my GPS when I am in the middle of no where. Having one thing to replace can be good some times.[/QUOTE]


You dont have to use multiple controllers for more than one panel. You can wire as many panels as you want in paralel as long as the total current does not exceed what the controller will handle. I tried panels in series with a mppt controller but found I lost power whenever one panel was shaded. Also tended to burn up diodes. Now have 2 panels in parallel to a single PWM controller and getting at least as much output.