Cable and Connectors

Wire size comes from the current the circuit carries and how far it runs. PV wire here is 10 AWG, sold by the foot or as ready-made extensions and home-run sets with MC4 connectors on the ends. Battery cable comes in #4, 2/0 and 4/0 with lugs fitted. If you're not sure of a size, that's one for your electrician. Undersized wire is where a mistake turns into a fire. Crimp MC4 pins with an MC4 crimper rather than pliers.