Wire to CC

[Cuemaker]

I have a 6-string combiner box, have 18 panels wired 3s, used 10ga PV wire to combiner box.
From the combiner box to the Charge Controller I need 4ga wire, about a 50' run.
All I can find is building wire, stranded THHN/THWN-2
Is this what everyone uses?

 

[timselectric]

Yes , if in conduit.
It's not rated for exposure to sunlight.