How it is calculated: Solar plant capacity is converted from kW to watts. DC current = plant power ÷ DC system voltage. Cable size is then calculated from conductor resistivity, total circuit length and the selected allowable voltage drop. The calculator includes both positive and negative conductors and selects the next larger standard cable size. This tool is intended for low-voltage DC solar/battery circuits. PV string-side cable sizing should use the actual string voltage and current from the module configuration. Final cable selection must also satisfy current-carrying capacity, insulation rating, temperature, installation method, protection devices and applicable electrical codes.