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Old 01-21-2017, 01:21 PM   #1
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Help choosing wire gauge for electrical setup

I've now got all the electrical components for my conversion:

6 x Renogy 12v 100w solar panels

From the panels to the charge controller ...
Pair of 10ft 10AWG male and female MC4 cables

To route those cables through the roof ...

LINKSOLAR Weatherproof ABS Solar Double Cable Entry Gland


The charge controller ...
Morningstar TS-MPPT-60 Tristar 60 amp

To the batteries ...

4 x Crown Cr430 6v 430aH golf cart batteries


To the inverter ...
Magnum MM1512AE 1500 watt PSW inverter/Charger

To 30 amp shore ...
True power 30 amp RV Power Twist Lock Inlet

So with all this in mind, can anyone tell me what gauge wire I'll need between all these pieces? I assume the 10 foot run from my panels to my controller is okay at 10 gauge. My charge controller will be less than 2ft from my battery bank. What gauge there? My four batteries will be strung in both series and parallel to create a 12v 860aH array. What gauge in there? Then to the 1500w inverter/charger, also approximately 2 ft from battery bank. Any ideas? From shore to the inverter?

You have all been so helpful. Thank you so much. I see a light at the end of the tunnel now.
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Old 01-21-2017, 02:02 PM   #2
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I hope you take lots of pictures for your setup and report back here! I'm also interested in using the renogys so I'd love to hear your review.

I do not have my solar setup done yet, I am not an electrician. Opinion of a amateur below.

You may be fine with 10 gauge but I would advise against it. Assuming you have 600 watts of solar panels, at 12v you'll have 50 amps of current to transfer (I know that it will be charging at 18v and you likely won't have a full 600 watts coming in at once). However from my amateur engineering standpoint I think it is wise to plan around max amperage(if not more) regardless.

According to this wire gauge chart you best use 8 gauge wire to transfer 50-65 amps for a 7-10 foot run. I personally plan on using 4 gauge, because I am a fool who is all about overkill (and I impulse bought 50 feet awhile ago). Considering you have more than 1k put into your setup, it makes sense to dump some relatively modest money into some nice thick wire to make sure you have more than enough copper to carry your solar amperage to your batteries.

I plan on using 00 wire between my batteries(because I also have 50 feet laying around), and using 4 gauge between my batteries and invernter charger (8 gauge should be plenty fine here, but I have lots of 4 gauge).

From shore to inverter, I would follow the chart and overkill a bit. My shore to inverter will probably be about 20 feet so I will try to do atleast 8 gauge.

I'm assuming you've visted handybob's website, and have a trimetric(or other) battery monitor, but if you haven't you definitely should. https://handybobsolar.wordpress.com/...ging-puzzle-2/

He agrees with most of the equipment you're using though, right on!

Good luck and come back with reports and pictures! LOTS of pictures! and details, and PICTURES!

edit: and make sure you charge your batteries at the correct voltage specified on the manufactures website. (14.8v I think for crown)
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Old 01-21-2017, 02:04 PM   #3
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you would think Renogy would specify.

here is the table that i used.

http://assets.bluesea.com/files/reso...on_chartlg.jpg
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Old 01-21-2017, 04:03 PM   #4
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I agree totally here, bigger is best. The only problem with that is finding all the lugs to make the connections fit. Takes a bit of improvising, but buy big copper as suggested to reduce resistance in any circuit.
Connection lugs can sometimes be adapted and drilled out to fit whatever bolts you encounter but make sure they are rated for at least the amperage carried by the wire/cable.
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Old 01-21-2017, 07:51 PM   #5
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Hi,

I also went with Renogy and am very delighted with thier products.

As for wire gauge, i half wonder if when i add more panels to mine if i might just designate half the panels, batteries, and a separate charge controller to the shop area. I'm never going to use more than 2k watts in the shop. This way i can keep from needing gigantic wires from the batteries. Split the system up into two. Hmm...

Excited to see what you decide. Good luck!
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Old 01-21-2017, 11:08 PM   #6
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600 watts at 12 volts is 50 amps, you need 8 gauge wire at minimum, 6 gauge would be better, the 30 amp shore power cable can be 10 gauge
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Old 01-22-2017, 02:04 AM   #7
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Your wires to your inverter need to be at least 2ga and really should be 0ga. 1500W at 12V is 125A, that's solidly in 0ga realm.
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Old 01-22-2017, 01:53 PM   #8
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Quote:
Originally Posted by Kubla View Post
600 watts at 12 volts is 50 amps, you need 8 gauge wire at minimum, 6 gauge would be better, the 30 amp shore power cable can be 10 gauge
The spec sheet indicates each panel will be putting out no more than 5.25 optimum amperage and 5.75 short circuit amperage. I should be under 36 amps total in full sun, no? Not to be argumentative but I think I'm pumping out closer to 400 watts / sun hour if I adjust for efficiency (generally ~66%) and with that correction I'm at 33 amps in full sun, closer to the manufacturer specifications.



If I am correct in understanding this, 600 watts at 12v isn't putting out 50 amps, but roughly 30% less than that. And reading the chart, from 20 amps all the way up to 50 amps I should be safe with 10ga.

I'm most concerned with the gauge I'm going to use between all the batteries wiring them in series/parallel. How do I calculate the proper amp draw on that? I see a lot of people using 00 (aka 2/0) and will probably go with that. I can get 10 feet for 50 dollars or so and that might cover all of my cable runs except shore power.

And what about from the batteries to the charge controller?
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Old 01-22-2017, 08:18 PM   #9
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Quote:
Originally Posted by warewolff View Post
The spec sheet indicates each panel will be putting out no more than 5.25 optimum amperage and 5.75 short circuit amperage. I should be under 36 amps total in full sun, no? Not to be argumentative but I think I'm pumping out closer to 400 watts / sun hour if I adjust for efficiency (generally ~66%) and with that correction I'm at 33 amps in full sun, closer to the manufacturer specifications.



If I am correct in understanding this, 600 watts at 12v isn't putting out 50 amps, but roughly 30% less than that. And reading the chart, from 20 amps all the way up to 50 amps I should be safe with 10ga.

I'm most concerned with the gauge I'm going to use between all the batteries wiring them in series/parallel. How do I calculate the proper amp draw on that? I see a lot of people using 00 (aka 2/0) and will probably go with that. I can get 10 feet for 50 dollars or so and that might cover all of my cable runs except shore power.

And what about from the batteries to the charge controller?
This should answer most of your questions.....

1) Solar panels to charger controller you need 8 gauge wire.
Solar panels will charger at around 18 volts, so it is less amps. You are correct in your 35 amp figure.

2) what ever you used from the solar panels to the charge controller is what you use on the battery side.

3) with a 1500 watt inverter, you will be drawing around 150 amps, so 2 gauge welding cable is plenty (rated at 200 amps at up to 50 feet)

4) use what ever you use to connect the inverter to the batteries to interconnect the batteries.

5) for shore cable run what ever it will be fused at... 15 amps=14ga. 30 amps=10ga.


I have a small solar setup on my house, I run 20 amps worth of panels through 75 feet of 10 gauge and then 30 feet of 8 gauge. My 1000 watt inverter is wired with 4 gauge welding cable.

The most important factor is the quality of the wire. I use welding cable over automotive battery cable as the insulation is more robust and has a higher temperature rating.

Most of my extension cords are home made out of sjoow wire, have you ever tried to run 15 amps on a 100 foot 14 gauge cord? It will trip the breaker, Mine will not.

As long as you use high quality wire, what I have listed will be fine.
Overkill is a waste of time and money if high quality components are used.
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Old 01-22-2017, 08:51 PM   #10
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TAOLIK, thank you for your response. I had actually been in communication with Handy Bob a few months ago and realized I should have just contacted him again. I'll get his opinion on everything and post it so that anyone designing a similar system can get their own HandyBob approved setup ;)

Hank, thank you for your advice. This helps me HUGELY. I had purchased some 2/0ga wire for ~$2.50/ft on Amazon (welders cable) awhile ago for a separate project.. With $30 worth of cable/lugs I should be able to hook up all my batteries and inverter. I upgraded on your recommendation on 8ga from the panels to charger to batteries and opted for 6ga as my inverter calls for a 6ga ground anyway. How do I hook up 6ga wire with an MC4 connector though? I can't find any MC4 cable in anything bigger than 10ga... =| It was only marginally more expensive at ~$1/ft.

Bob did tell me I might have an issue using the inverter I purchased as it doesn't have internal ground and neutral bonding. I'll update about that after I call him tomorrow.

Thanks again, you have all been very helpful.
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