You would need at least #4 gauge wire (awg) to move 18 amps 30 feet with a minimum voltage drop of 3% or less, an acceptable loss. . Proper solar panel wire sizing is critical for system safety, efficiency, and compliance with electrical codes. In addition, if the wires are undersized, there is a risk that the wires may heat. . Disclaimer: This calculator provides general wire-size estimates based on user inputs and standard ampacity/voltage-drop assumptions. Need Help? Calculate the appropriate wire gauge and type for your solar installation. The American Wire Gauge (AWG) system determines wire capacity, where lower gauge numbers (such as 10 AWG, 6 AWG, or 1/0 AWG) indicate. .
[PDF Version]
