How to Fuse your Solar System - Renogy United States For instance, if you have one of our 40Amp charge controllers, we would recommend using an 40Amp fuse second fuse between your solar panels and charge controller is a little bit different to figure out. The size of this fuse is dependent on how many solar panels you have and how they are connected (series, parallel, or series/parallel). How to properly fuse a solar PV system - WindyNation In this case, the battery, wires, and AC/DC inverter will be safely disabled by the fuse. Solar Panel fusing. Commercially made solar panels over 50 watts have 10 gauge wires capable of handling up to 30 amps of current flow. If you connect these panels in series, there will be no increase in current flow so fusing is not required for this string.