1. Current flow in amps. Pick a wire gauge that is big enough to carry the amount of current (in amps) that will be flowing through your system. For instance, if you have one of Renogy 40Amp charge controllers, we would recommend using an 8AWG wires.

2. Charge controller terminals. Some charge controllers have small terminals that won’t accept wire thicker than a certain gauge. Check to see if compatible wire gauges are listed in your charge controller’s manual.

There are three different locations that we recommend installing fuses or breakers: first, between the charge controller and battery bank, second, between the charge controller and solar panels, and third would be between the battery bank and inverter.

To determine the fuse size needed between the charge controller and battery bank you simply match the amperage rating on the charge controller. For instance, if you have one of our 40Amp charge controllers, we would recommend using an 40Amp fuse.