Wire gauge for DC

jamesnewman01377

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I need a little help, I'm a beginning so bear with me. I have 6 solar panel wired in series to a switch, from the switch to the Growatt inverter is about 130 feet, how do I now what gauge wire do I run for DC, the panel are 250w, 37.6v open circuit, VMP 30.3, at 8.27 amps, in series (if my math is right) that would be 225.6v an 8.27 amps, thanks, James
 

sunshine_eggo

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You start with cable that can handle the current.

Then you use a voltage drop calculator to determine % voltage drop, which equates to % power lost.


Click estimated resistance tab and plug in the numbers (use Vmp and Isc):




1637188618461.png

10awg can more than handle 8.27A, and it only has a 1.18% voltage drop - anything less than 3% is pretty great.

Even 14awg would be just under 3%.
 

smoothJoey

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I need a little help, I'm a beginning so bear with me. I have 6 solar panel wired in series to a switch, from the switch to the Growatt inverter is about 130 feet, how do I now what gauge wire do I run for DC, the panel are 250w, 37.6v open circuit, VMP 30.3, at 8.27 amps, in series (if my math is right) that would be 225.6v an 8.27 amps, thanks, James
How far from the switch to the panels?
 

jamesnewman01377

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You start with cable that can handle the current.

Then you use a voltage drop calculator to determine % voltage drop, which equates to % power lost.


Click estimated resistance tab and plug in the numbers (use Vmp and Isc):




View attachment 72628

10awg can more than handle 8.27A, and it only has a 1.18% voltage drop - anything less than 3% is pretty great.

Even 14awg would be just under 3%.
I asked about the distance between the switch and the panels.
I’m sorry, I would say 15 foot, the panels are mounted on a roof of a dock building and the switch is mounted just under the roof line.
 

smoothJoey

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I’m sorry, I would say 15 foot, the panels are mounted on a roof of a dock building and the switch is mounted just under the roof line.
14 awg would be just under 3% voltage drop.
10 awg would be a little over 1% voltage drop.
 

jamesnewman01377

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Jun 10, 2021
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You start with cable that can handle the current.

Then you use a voltage drop calculator to determine % voltage drop, which equates to % power lost.


Click estimated resistance tab and plug in the numbers (use Vmp and Isc):




View attachment 72628

10awg can more than handle 8.27A, and it only has a 1.18% voltage drop - anything less than 3% is pretty great.

Even 14awg would be just under 3%.
Thank you.
 

smoothJoey

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What’s the difference between AWG and THHN wire?
AWG is the measure of the conductor's diameter.
THHN is a type of wire. THHN is useful wire but it is not suitable for your application.
The insulation on THHN is not designed for exposure to the sun.
You need wire specifically meant for your application.
 

jamesnewman01377

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AWG is the measure of the conductor's diameter.
THHN is a type of wire. THHN is useful wire but it is not suitable for your application.
The insulation on THHN is not designed for exposure to the sun.
You need wire specifically meant for your application.
I meant the wire between the switch and the inverter, it will be in conduit.
 
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