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PV Wire Tool

Solar Wire Size Calculator

// SIZE PV SOURCE AND OUTPUT CONDUCTORS FROM MODULE ISC, PARALLEL STRINGS, RUN LENGTH, VOLTAGE, AMPACITY MARGIN, AND VOLTAGE-DROP TARGET //

PV_INPUTS

Use the short-circuit current from the module nameplate.

Count strings combined on this conductor segment.

Distance from array combiner to controller, inverter, or disconnect.

PV_SIZE_RESULT
Recommended minimum
8 AWG

8.4 mm², passing ampacity and 3% voltage drop.

Estimated drop
2.28%

3.42 V at the PV design current.

Array Isc
22.4 A
Required ampacity
34.9 A
Drop current
28.0 A

This is a planning minimum. Verify conductor insulation, wet-location rating, rooftop temperature correction, terminal ratings, and overcurrent protection before installation.

14 AWG
2.1 mm²
Ampacity
20.0 A
Drop
9.17%
Status
No
12 AWG
3.3 mm²
Ampacity
25.0 A
Drop
5.76%
Status
No
10 AWG
5.3 mm²
Ampacity
35.0 A
Drop
3.61%
Status
No
8 AWG
8.4 mm²
Ampacity
50.0 A
Drop
2.28%
Status
Pass
6 AWG
13.3 mm²
Ampacity
65.0 A
Drop
1.47%
Status
Pass
4 AWG
21.1 mm²
Ampacity
85.0 A
Drop
0.92%
Status
Pass
3 AWG
26.7 mm²
Ampacity
100 A
Drop
0.73%
Status
Pass
2 AWG
33.6 mm²
Ampacity
115 A
Drop
0.58%
Status
Pass
1 AWG
42.4 mm²
Ampacity
130 A
Drop
0.46%
Status
Pass
1/0 AWG
53.5 mm²
Ampacity
150 A
Drop
0.36%
Status
Pass
2/0 AWG
67.4 mm²
Ampacity
175 A
Drop
0.29%
Status
Pass
3/0 AWG
85.0 mm²
Ampacity
200 A
Drop
0.23%
Status
Pass
4/0 AWG
107.2 mm²
Ampacity
230 A
Drop
0.18%
Status
Pass
PV_CURRENT_BASIS

PV source and output circuits are commonly sized from module short-circuit current, not only operating current.

The 156% option represents a conservative NEC-style planning screen: array Isc times 125%, then another 125% ampacity factor.

Use the 125% option only when your design method, equipment listing, or local code path supports that basis.

VOLTAGE_DROP

Voltage drop is calculated over the round-trip DC conductor path.

Low-voltage battery and charge-controller circuits are much more sensitive to drop than 300 V or 600 V PV strings.

A 2% to 3% target is typical when energy harvest and inverter performance matter.

FIELD_LIMITS

Rooftop conduit, high ambient temperature, and bundled circuits can require additional ampacity correction.

Outdoor PV wiring must use insulation and cable assemblies rated for the actual wet, UV, and temperature exposure.

Always coordinate conductor size with disconnects, fuses, terminals, combiner boxes, and equipment instructions.

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