Yup, I size up the solar wire in case I want to add more panels as a parallel set, that way I can over panel the charge controller and ensure I get the best amperage even in poorer light. I've also got the panels on a 50ft cord to deploy them in the sun, I thing upsizing the wire helps with resistance over a long run. For now with one string, yes, it's oversized.
I was referring to your battery wire not your PV wire.
Also, remember...if the length of your cord is 50' it is actually a 100' run when calculating wire size.
