Help Needed with Wire Sizing

[jolondon]

Hi I am trying to size the cable (AWG) for the run from my panels to the inverter. I am getting estimates from various calculators and manual methods that are all over the place but generally puts it at 8 AWG. I am a newbi so if some of you can confirm I would greatly appreciate it.

Number of panels: 8
VOC: 50.32
Amps: 14.25
Distance: 111 meters (367 feet)
Wired in Series
Acceptable loss: 3%

I am in Costa Rica and would guess the ambient temperature is around 30 Celsius.

Thanks.

 

[HarryN]

The calculators are based on the round trip wire length, so you will need to use ( 2 ) x ( 111 meters) for the distance if you haven't already.

Sometimes it makes sense to just accept that the power from one panel will be doing nothing but pushing the electrons from the array to the charger.

 

[jolondon]

thanks..can you explain that to me? Why do I need to double the length (why round trip)?

 

[timselectric]

It takes two wires to make a circuit. Round trip length includes both wires.
I have heard people talk about some voltage drop calculators that don't account for this, and you have to double the length. (Stupid on the designer of the calculator) and I wouldn't use one like that.
But most calculators (at least all of the good ones) account for it.
I use the Southwire calculator. It has served me well for many years.

 

[timselectric]

#8 AWG is what I am getting, also. At a 2.36% voltage drop.
But, #10 is only a 3.76% voltage drop and a lot cheaper.
And not really a problem for a PV circuit. The difference isn't worth the copper cost.

 

[jolondon]

It takes two wires to make a circuit. Round trip length includes both wires.
I have heard people talk about some voltage drop calculators that don't account for this, and you have to double the length. (Stupid on the designer of the calculator) and I wouldn't use one like that.
But most calculators (at least all of the good ones) account for it.
I use the Southwire calculator. It has served me well for many years.

 

[jolondon]

Thank you. But to figure out the wire size and say a wire is ten feet isnt the current just travellnig ten feet? I understand that to figure the amount of wire you double it but ins't distance independent of that?

 

[timselectric]

Thank you. But to figure out the wire size and say a wire is ten feet isnt the current just travellnig ten feet? I understand that to figure the amount of wire you double it but ins't distance independent of that?

Current travels in a circuit (circle) through the entire length.
It's not like a water hose, where water enters one end and leaves the other.

 

[jolondon]

It takes two wires to make a circuit. Round trip length includes both wires.
I have heard people talk about some voltage drop calculators that don't account for this, and you have to double the length. (Stupid on the designer of the calculator) and I wouldn't use one like that.
But most calculators (at least all of the good ones) account for it.
I use the Southwire calculator. It has served me well for many years.

Hi I used the Southwire calculator. Are you saying that I only put it in teh one way distance and it accounts for the rest?

 

[timselectric]

Hi I used the Southwire calculator. Are you saying that I only put it in teh one way distance and it accounts for the rest?

Correct