Solar Panel Wire Size Calculator
Find the correct AWG wire gauge for every cable run in your solar panel system.
Free sizing tool
Solar Panel Wire Size Calculator
Find the correct AWG wire gauge for every cable run in your solar panel system.
Cable parameters
Acceptable voltage drop
AWG to mm² reference
| AWG | mm² | Max amps (Cu, 60°C) | Common use |
|---|---|---|---|
| 14 | 2.08 | 15 A | Lighting circuits |
| 12 | 3.31 | 20 A | General outlets |
| 10 | 5.26 | 30 A | Small solar, dryer |
| 8 | 8.37 | 40 A | Solar string, range |
| 6 | 13.30 | 55 A | Sub-panel feed |
| 4 | 21.15 | 70 A | Battery bank |
| 2 | 33.63 | 95 A | Large battery bank |
| 1/0 | 53.49 | 125 A | Main service |
| 2/0 | 67.43 | 145 A | Inverter feed |
| 4/0 | 107.22 | 195 A | Heavy inverter feed |
Based on NEC ampacity tables for copper at 60°C. Always verify with local electrical codes and a licensed electrician.
How to Size Wire for Solar Panels
This solar panel wire size calculator determines the correct AWG gauge for every cable run in your photovoltaic system. Enter the current from your solar array (Imp rating from the panel datasheet), the one-way cable length, and the system voltage. The calculator outputs the minimum wire gauge that keeps voltage drop within the recommended 3% limit for PV circuits.
There are three separate cable runs in a solar system, each with different current levels and sizing requirements. The panel-to-controller cable carries the full array current at panel voltage. The controller-to-battery cable carries the charge current at battery voltage (higher current than the panel side for MPPT controllers). The battery-to-inverter cable carries the highest current and needs the thickest wire. Use this calculator for each run separately.
Quick Reference: Solar Panel Wire Sizes
| Array Size | Panel-to-Controller | Controller-to-Battery | Battery-to-Inverter |
|---|---|---|---|
| 200W (1 panel) | 14-12 AWG | 12-10 AWG | 10-8 AWG |
| 400W (1 panel) | 12-10 AWG | 10-8 AWG | 8-6 AWG |
| 800W (2 panels) | 10-8 AWG | 8-6 AWG | 6-4 AWG |
| 1,200W (3 panels) | 8-6 AWG | 6-4 AWG | 4-2 AWG |
| 2,000W+ (5+ panels) | 6-4 AWG | 4-2 AWG | 2-1/0 AWG |
These are approximations for 12V systems with 3-meter cable runs. For exact sizing at your specific current, length, and voltage, use the calculator above. Higher system voltages (24V, 48V) allow significantly thinner wires for the same power. For a complete guide covering all three runs, see our Solar Cable Sizing Guide.
Solar Cable Types: PV Wire vs THHN vs USE-2
Outdoor solar cable runs must use UV-rated, weather-resistant wire. PV Wire (also called “solar cable”) is specifically designed for photovoltaic systems — rated for 2,000V, UV-resistant, and suitable for direct burial. USE-2 is acceptable for underground conduit runs. Standard THHN house wire is NOT suitable for outdoor solar installations — it degrades in UV exposure within 2-3 years, becoming brittle and cracking. Always use PV Wire or USE-2 for any cable run exposed to sunlight.
For cable sizing from panel to charge controller specifically, see our detailed guide: What Size Cable: Solar Panel to Charge Controller. For battery-to-inverter sizing, see our battery-to-inverter wire guide.
Frequently Asked Questions
What size wire for a 200W solar panel?
For a 200W panel at 12V with a 3-meter run: 12 AWG is sufficient for the panel-to-controller cable (about 11A at 18V). For longer runs (5+ meters), use 10 AWG. The controller-to-battery cable at 12V carries higher current (about 16A) and needs 10 AWG minimum.
What size wire for a 400W solar panel?
A 400W panel produces about 22A at 18V. At 3 meters: 10 AWG for the panel-to-controller run. At 5 meters: 8 AWG. The controller-to-battery side at 12V draws about 35A and needs 8 AWG minimum for short runs or 6 AWG for runs over 2 meters.
What gauge wire for solar panels to charge controller?
The wire gauge depends on three factors: the array’s maximum current (Imp), the cable length, and the allowable voltage drop (3% for PV circuits). For most residential rooftop installations with 3-5 meter runs, 10 AWG handles up to 30A and 8 AWG handles up to 40A. Use the calculator above for exact sizing at your specific configuration.