Help with wiring size - First time using MPPT

[4321loco]

I currently installed a 1500 watt array ( 6 Panels) for testing purposes and will eventually go to my off grid cabin.

My question is what size wire should I use from the solar array to charge controller. I may run 2 panels at 67+/- VDC or 3 panels at 99+/- VDC. I received my MPPT charge controller today and ran a quick test using 75' of 10 AWG 2/C THHN/THWN DRY TC-ER Wire.



Would this 10/2 work at 75 feet max distance for 1500 watts?
I know on AC 10/2 can handle 30 Amps just want to make sure if I need to order more parts tonight.



The Panels I have are Trina 250 w panels with specs: 37.6VOC, VMP 30.3 and ISC 8.85.
My battery bank will be 24v for now running used 8G8DLTP batteries.

[organic farmer]

... My question is what size wire should I use from the solar array to charge controller.

You are better served by using MC4 cables.

[foo1bar]

I currently installed a 1500 watt array ( 6 Panels) for testing purposes and will eventually go to my off grid cabin.

My question is what size wire should I use from the solar array to charge controller. I may run 2 panels at 67+/- VDC or 3 panels at 99+/- VDC. I received my MPPT charge controller today and ran a quick test using 75' of 10 AWG 2/C THHN/THWN DRY TC-ER Wire.
.

Amperage and voltage drop is determining factors for wire size - not AC or DC.

Separate from wire size -
I don't know of any way to directly, safely connect THWN to an MC4 connector. All MC4 connectors I know of use/expect PVwire. And the THWN wire the insulation isn't thick enough to get a good seal to the MC4 connector's plastic to keep it weathertight. (not to mention can't have THWN wire outside of conduit/boxes as it's not UV resistant)

You can either get MC4 connectors already on PV-wire and inside a box transition the wire to THWN, or buy some wire and some MC4 connectors to put on the wire and make your own. (Or possibly you can go with PV-wire all the way from the array to the charge controller- just make sure you're good as far as any conduit fill, etc.)

For the transition from PVwire to THWN, I think Polaris connectors do a good job.

[4321loco]

You are better served by using MC4 cables.

If I were to buy some MC4 extensions what gauge wire should I buy to make it 75 feet. How many runs will I need to feed the 1500w array.

[4321loco]

. And the THWN wire the insulation isn't thick enough to get a good seal to the MC4 connector's plastic to keep it weathertight. (not to mention can't have THWN wire outside of conduit/boxes as it's not UV resistant)

You can either get MC4 connectors already on PV-wire and inside a box transition the wire to THWN, or buy some wire and some MC4 connectors to put on the wire and make your own. (Or possibly you can go with PV-wire all the way from the array to the charge controller- just make sure you're good as far as any conduit fill, etc.)

The wire I used for testing shows Sun Resistant and is like a duplex wire if I am correct. I also soldered MC4 connectors and you are correct about the weathertight seal, the wire fits loose on connector. If I were to buy wire what gauge do I need for 1500w at 75' of distance.

I was also thinking of adding a combiner box under the array and then running the PV wires into the box.

Thanks again.

[organic farmer]

If I were to buy some MC4 extensions what gauge wire should I buy to make it 75 feet. How many runs will I need to feed the 1500w array.

I did everything with MC4, I did not need any other type of wire.

[foo1bar]

I did everything with MC4, I did not need any other type of wire.

MC4 is the connector, not the type of wire.
There are MC4 "extension cables" - where there are MC4 connectors on each end of a length of PV wire (at least I assume it's PV wire - could be something equivalent.)
You can get them in pre-cut lengths (ex. 10ft or 20ft or 100ft) or you can order them from places in a length that you specify.
And if you use these "extension cables", you need to make sure any time they are going through conduit that you're doing appropriate fill ratios. (And they probably will not be a "standard" size to make it easier to plug into a conduit fill calculator)

[foo1bar]

I also soldered MC4 connectors

I only know of crimp-on MC4 connectors. I do not know of any solder-able ones.
(And the crimping should be done with a proper crimping tool - not the crappy crimping section on a wiring pliers. I would not trust a crimp done with my wiring pliers for anything serious. )

If I were to buy wire what gauge do I need for 1500w at 75' of distance.

What voltage/amperage?
At 10A/150V, I think you could get away with 12 AWG or smaller.
At 30A/50V, 10 AWG might work - I'd calculate the voltage drop as well to see if it needed to be bigger because of that.

[checkthisout]

#10 wire. Just look at the amps on the tags on your solar panel.

If the panel says 8 amps, then each group of series panels will run 8 amps.

So 2 parralelled groups of 3 8 amp panels in series equals 16 amps.

#12 wire would work but in my opinion just go with 10awg for general principles.

[Ho jo]

10 awg @ 99 volts @ 75 foot @ 16 amps gives the recommended less than 3%.
(2.42% voltage drop)

[bcroe]

Here by the time connections were made, the total wire loop length was
quite a bit MORE than twice the airline distance. I try to keep losses in a
wire run, well under 2%, but it is your money.

Any MC4 used outdoors must be tightly sealed around the wire, or expect
early failures. MC4s are cheap with no noble metal contact plating, I use
NoOx on them now after some failures. good luck, Bruce Roe

[4321loco]

Thanks you all for the wire recommendations and tips. I am having an issue with the system so will be making another thread if I cant find the answer.

Thanks