8 AWG or 6 for solar?

captaingregger

New Member
Hi All,

First post here.

I’m more or less new to this. My first a build/ solar package set up is for a van. most videos online show 8AWG from the panels to the charge controller. However one installer I spoke with suggested for my sizing I should go with 6 AWG, if I plan to expand my solar down the road.

Here are the stats:
I‘m building for a 400 to 600W of solar (but will expand to 800-1,000W if needs dictate downline)
Victron 30 amp MPPT charge controller
19’ van so the cable run is probably 15’ from solar panels to the charge controller.

i spoke to Windy Nation and he walked me through the ampacity chart and said I’m right in the edge in the best of lighting conditions. he thought 8 AWG is acceptable but said 6 wouldn’t hurt either.

I’m also confused about how to connect 6AWG is MC4 connectors only fit up to size 8 AWG.

thanks for any and all advice!
 

Forbisher

Փփքխմպ
Hi All,

First post here.

I’m more or less new to this. My first a build/ solar package set up is for a van. most videos online show 8AWG from the panels to the charge controller. However one installer I spoke with suggested for my sizing I should go with 6 AWG, if I plan to expand my solar down the road.

Here are the stats:
I‘m building for a 400 to 600W of solar (but will expand to 800-1,000W if needs dictate downline)
Victron 30 amp MPPT charge controller
19’ van so the cable run is probably 15’ from solar panels to the charge controller.

i spoke to Windy Nation and he walked me through the ampacity chart and said I’m right in the edge in the best of lighting conditions. he thought 8 AWG is acceptable but said 6 wouldn’t hurt either.

I’m also confused about how to connect 6AWG is MC4 connectors only fit up to size 8 AWG.

thanks for any and all advice!
Welcome to the forum.
You need more info to calculate wire size
What size watts panels are you using?
How are you wiring them? Parallel?
Series? Or Series and Parallel?
Voc
Vmp
Imp
6 awg sounds bigger than needed.

600 watts panels at 12V is 50A
400 watts panels at 12V would work with a 30A SCC.
 

DThames

Solar Addict
Look for a charge controller that can take a higher input voltage. I have one that can handle 100v and another that can handle 150v. For the first one, I have 4, 300w panels (40v open circuit) connected 2 series, 2 parallel which is 20 amps at less than 80v (under load). My charger that can take 150v, can handle 6, 300w panels, 3 series, 2 parallel and still just be 20 amps. So I could wire for 20 amps and use 1 series, 2 parallel for 600w, or 2 series, 2 parallel for 1200w, or 3 series, 2 parallel for 2400v all with 10 gauge wire. Series allows the amps to be lower, but you need a charger that can take higher input voltages, so shop and plan for that, so you can use smaller wire. Leave yourself some head room in the voltage input, so you can just add to the series string if you want to add more solar watts.
 

chrisski

Solar Addict
With MC4 connectors, you’d need to watch the ratings for amperage even if you could get it to 6 AWG. Most are only rated to 30 amps. I have a 30 amp extension cable for some portable panels that I used a foot of 10 AWG to attach to each end so I could put an MC4 connector on it, and then put a 30 foot piece of 6 AWG wire between them. I did this to prevent voltage loss.

With my six 100 watt panels on the roof, they could put out 36 amps if placed in parallel, which exceeds the MC4 connector rating and the 10 AWG wire ampacity for 60 C insulation. I tried 2S2P, but the wire loss calculation for the 45’ I wanted was too big for 10 AWG, but 3S2P worked.

I like using 10 AWG cable to a combiner, and from the combiner to the SCC, I will use 6 AWG.

You need to do calculations as mentioned. I like this:


No way around that pesky math stuff.
 
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