Panel and controller wire

[Bluedog225]

I’m at the hooking up panels phase and I’ve managed to confuse myself. The 10 gauge wire I’m seeing for use with panels doesn’t appear to be the super fine wire needed for the Victron controller. See below.

How are people handling this? Is it 10 gauge outdoor rated solar panel wire to a combiner box then fine strand to the MPPT? Or is it a junction box near the controller then switch to fine strand wire?

In one part of my system I’ll have one panels feed the MPPT, do I just butt joint the fine wire to the panel output wire?

Any thoughts appreciated.

 

[offgrid-curious]

I'm curious about this as well. I just wired up my system and I'm not using fine stranded wire like they recommend.

In case of thicker strands the contact area will be too small and the resulting high contact resistance will cause severe overheating, eventually resulting in fire. See below figure for examples of what cable to use and not to use.

This sounds a bit dramatic to me? I feel like it depends on a few different variables. In my case I have a 48v system with a 150/45 SCC where my PV connection is using 8 gauge wire and my battery connection is using 6 gauge wire. I don't expect to ever see more than 25A of PV current, and because it's a 45A charger, I should not exceed 45A on the battery circuit. Those wire gauges are well within the tolerances for the expected amperage, so I'm not concerned there.

I've also torqued the screw terminals to 20 in-lbs for the 8 gauge and 35 in-lbs for the 6 gauge wire. I just used the values that Midnite recommends for their breakers. Seeing as my Midnite breakers are also using screw terminals, I feel like this should be ok? Would the Victron screw terminals really be that different or have significantly more contact resistance?

I also don't expect my system to be running at a sustained load for extended periods of time, e.g. charging at 45A for hours.

Ultimately, I think I'll check the temperature of the SCC under load before rewiring everything.

 

[wiseacre]

Where there's a sufficient bank account there's a way.
Current Connected has you covered - https://www.currentconnected.com/product/solar-pv-dc-quick-disconnect-switch/

 

[Bluedog225]

Well this is getting frustrating.

Does anyone know of a source of 10 awg that meets the Victron standard? I’ve tried my usual go to source, Boatwireusa.com. No luck. Amazon is a dumpster fire. I’d like a quality, preferably American made, source.

Thanks

• Example of suitable cable: class 5 "Tri-rated" cable (it has three approvals: American (UL), Canadian (CSA) and British (BS)).

 

[Bluedog225]

I called currentconnected. They recommended using their 7 strand wire with the Victron charge controller.

Seems unwise given the Victron warning. To wit:

• In case of thicker strands the contact area will be too small and the resulting high contact resistance will cause severe overheating, eventually resulting in fire.

Maybe Dexter would be willing to shed some light.



@HighTechLab

 

[dopeassjackson]

Strand of wire makes nearly no difference in a DC circuit.
Amazon does have good US made wire. Look up national wire. They sell PV wire made in NY and a very good price even when you compare it to chinese stuff. Also its solid copper not CCA.

 

[Bluedog225]

It’s a pretty solid requirement from the Victron engineers. Do you have a basis for thinking it doesn’t matter?

 

[DougfromdaUP]

I don’t think the connector victron uses is robust enough to properly grip solid or low strand count wires.

South wire makes many #10 wires with 105 strands and high temp insulation.

You will pay a lot for them.

Wireandcableyourway has diesel locomotive cable for about a buck a foot, for sale by the foot, that’s #10 with hundreds of strands

 

[Bluedog225]

Thanks. I’ll check southwire.

I did find this at northern Arizona wind and solar. I think it qualifies.

MTW Rated Stranded Copper Cable #10 AWG in Black

NOTE: This wire is sold by the foot.

www.solar-electric.com

 

[DougfromdaUP]

The DLO number 10 doesn’t have hundreds of strands, only 27

 

[42OhmsPA]

I've used this, https://gregsmarinewiresupply.com/product/10-awg-tinned-marine-primary-wire/, with ferrules coming from the combiner box to the mppt. I've also used 7 strand PV wire with ferrules... Haven't had any issues with either. The marine wire is much easier to work with...

 

[Q-Dog]

Well this is getting frustrating.

Does anyone know of a source of 10 awg that meets the Victron standard? I’ve tried my usual go to source, Boatwireusa.com. No luck. Amazon is a dumpster fire. I’d like a quality, preferably American made, source.

Thanks

• Example of suitable cable: class 5 "Tri-rated" cable (it has three approvals: American (UL), Canadian (CSA) and British (BS)).

West Marine has it in stock in their stores, if you have one nearby and need it now-ish.

 

[Bluedog225]

I guess only a bit of this is needed? Splice it to the “regular” pv wire at the end of the run so you have the right wire for the controller? Seems odd.

 

[Bluedog225]

The DLO number 10 doesn’t have hundreds of strands, only 27

Which is the DLO wire? Sorry, I don’t follow.

 

[Q-Dog]

I guess only a bit of this is needed? Splice it to the “regular” pv wire at the end of the run so you have the right wire for the controller? Seems odd.

Put a disconnect near the charge controller. Make the transition there.

 

[Bluedog225]

Can anyone interpret this?

“Type III 105/.0100 Stranding”

I’m guessing .0100 strand size. And I’m guessing that’s inches. Maybe 105 strands? Type III isn’t coming up useful in google.

 

[42OhmsPA]

Can anyone interpret this?

“Type III 105/.0100 Stranding”

I’m guessing .0100 strand size. And I’m guessing that’s inches. Maybe 105 strands? Type III isn’t coming up useful in google.

You're correct.
https://www.coonerwire.com/stranding-chart/ Google fails.

 

[DougfromdaUP]

Go to the website of the cable manufacturer. It will give you all the certifications, etc.

For examplehere's the southwire I mentioned earlier

 

[42OhmsPA]

I guess only a bit of this is needed? Splice it to the “regular” pv wire at the end of the run so you have the right wire for the controller? Seems odd.

You could run it like @Q-Dog suggested or the other way. Add a disconnect at the array and make your transition; run the 'regular' wire back and keep the PV wire short.
I've been using the same wire wire I linked for ~30' run with a - 240VDC array clipped at 22A by the mppt since mid fall of last year with no issues. (well I did have a fuse getting hot but that was no fault of the wire, just a dumbass installer that undersized the fuse...)

 

[seneysolar]

Aims has pv wire in 500ft rolls. The 10ga is 84 strand.