wire size

[wren]

I would like to confirm if a 6 gauge wire from 2 parallel wired 400 w, 24 v modules is sufficient, covering 20 feet between modules and gro watt All in One is sufficient. I am attaching a spec sheet of the module. my battery bank consists of 4x 12 v AGM batteries , each 200Ah. I don't know if that matters.

 

[John Frum]

Your panels can supply 2 * 9.9 amps = 19.8 amps @ 43.5 volts.
Round trip distance is 40 feet.
10 awg will give you just under 2% voltage drop.
6 awg will give you less than 1% voltage drop.
I don't think mc4 connectors work with 6 awg cable.
Are you doing a combiner box or similar?

Interactive Wire Size Calculator

Battery Chargers, Inverters, Solar Components, and Wiring Supplies for Boats, RVs, and Off-Grid Applications.

baymarinesupply.com

 

[FilterGuy]

In calculating wire size, there are two different calculations needed:

1) Can the wire safely handle the expected current.
In your case the Isc is 9.9A for a total of 19.8A. 6 Gauge wire is far more than enough to safely handle 20A.

2) Is the voltage drop acceptable.
In your case you will have a 40ft round trip. 6 AWG would have well under 2% Voltage drop.

Final Answer: 6AWG is probably overkill, but it will work.

 

[OffGridInTheCity]

I would like to confirm if a 6 gauge wire from 2 parallel wired 400 w, 24 v modules is sufficient, covering 20 feet between modules and gro watt All in One is sufficient. I am attaching a spec sheet of the module. my battery bank consists of 4x 12 v AGM batteries , each 200Ah. I don't know if that matters.

20ft is 'very short' in solar setup distance terms in my opinion - e.g.10awg is fine for such short distances between the Panels and the GroWatt and as @smoothJoey points out will be compatible with some MC4 connections to the panels. From the GroWatt to the battery would depend on the amps needed for the GroWatt to deliver the AC output.

 

[wren]

I just learned that wire size 6 is not compatible with MC4 connectors. Combiner box means I have to bring size 6 cables into the box and connect the parallel wired modules in that box with the #6 wires?

 

[John Frum]

I just learned that wire size 6 is not compatible with MC4 connectors. Combiner box means I have to bring size 6 cables into the box and connect the parallel wired modules in that box with the #6 wires?

Since you only have 2 panels I don't think you need a combiner box.
Did you already purchase 6 awg wire?

 

[wren]

no I have not bought that wire yet. should I do 10 gauhe instead

 

[John Frum]

no I have not bought that wire yet. should I do 10 gauhe instead

Yes 10 awg will be fine.
I explained earlier in this thread and included a link to an online calculator.