PV Voltage drop calculator ‣ Clever Solar Power

Use this calculator to size the wire between your solar panels and charge controller. Enter your PV voltage, current, and cable length, and it will estimate voltage drop and recommend a wire size in standard metric sizes and AWG. You can also switch between a 20°C (used in the book/EU) method and a 75°C (NEC) method. The NEC method can result in a larger wire recommendation because they use a higher conductor temperature.

Voltage Drop Calculator for Solar Panels

Conductor material

Conductor temperature data

Panel Vmp (V)

Panels in series

PV short-circuit current (Isc) (A)

Parallel strings

Safety factor

Target max voltage drop (%)

One-way distance

Distance unit

Enter values and click Calculate.

Notes: This calculator automatically uses 2 × one-way distance (out and back). Current is computed using I = Isc × strings × 1.25. PV cable is commonly sold as 4 mm², 6 mm², or 10 mm². This calculator rounds up to the next available PV size: 4 mm² (12 AWG), 6 mm² (10 AWG), 10 mm² (8 AWG).