Double up on 10 gauge wire to get less voltage drop?

[leosantamana]

I came across 200' of 10 gauge wire. I am only running 3 PVs (90 watts each), which are only 30' away from controller. Since I have an abundance of 10 gauge wire (an extra 140'), would it be wise to double up on 10 gauge from panels to CC, and from CC to battery(ies), or should I drop the money and go for larger gauge? (CC handles up to 6gauge).

If yes, what does doubling 10 gauge provide (6 gauge?).

[Sunking]

If you go by electrical codes, it cannot be done unless certain conditions are met like only conductors of 1/0 AWG or larger. The reason for using parallel conductors is mostly used where it would be difficult to run larger wire say like 500 MCM to meet minimum capacity requirements, rather then a voltage loss specification. Example if you used a 200 amp fuse but bends would make it impossible to use 500 MCM you could use 3 parallel 1/0 AWG conductors. Low voltag eis another animal where voltage loss becomes significant. 3% at 12 volts is 0.36 volts and at say 270 volts is 8 volts.

OK let me make it clear I do not condone using parallel 10 AWG conductors. What I will say is if the maximum designed current does not exceed the safe capacity of single 10 AWG conductor, there is not a safety issue involved in the event one or more parallel conductors should fail for any reason. Example say the maximum current is 30 amps, is no problem for 10 AWG, and the only consequence is you would suffer higher voltage loss, but no thermal damage.

Take that for what it is worth.