Solar Wire Gauge Calculator
PV wire size from Isc with the NEC 1.56× design factor AND a voltage-drop target — returns the AWG that satisfies both.
Use sunlight-resistant, double-insulated PV wire (PV1-F / USE-2) outdoors. Voltage drop on the PV side is pure energy loss every sunny hour for 25 years — that's why solar targets 1–3 %, tighter than general wiring. MPPT controllers tolerate drop better than PWM (they convert excess voltage to current), but the watts are still gone. Always fuse parallel strings per the panel's series-fuse rating.
Solar Wire Gauge Calculator computes the PV wire size that satisfies both code current and your voltage-drop target — free, instant and private in your browser. Solar DIYers, van/camper builders and installers checking a design use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About Solar Wire Gauge Calculator
Solar Wire Gauge Calculator computes the PV wire size that satisfies both code current and your voltage-drop target using the standard engineering relation: design current = 1.56·Isc (NEC 690.8); area A = 2ρLI/Vdrop; the larger conductor wins. Worked live: an 11.5 A string over 12 m at 2 % allowed drop on 36.6 V needs AWG 9–10 copper. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use Solar Wire Gauge Calculator
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use Solar Wire Gauge Calculator?
- ✓Implements the real formula — design current = 1.56·Isc (NEC 690.8) — with the substitution shown, not a black box
- ✓Built for solar DIYers, van/camper builders and installers checking a design
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate solar wire gauge?+
The PV wire size that satisfies both code current and your voltage-drop target follows design current = 1.56·Isc (NEC 690.8); area A = 2ρLI/Vdrop; the larger conductor wins. For example, an 11.5 A string over 12 m at 2 % allowed drop on 36.6 V needs AWG 9–10 copper. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Why multiply panel current by 1.56?+
Two stacked code factors: ×1.25 because PV output is continuous, and ×1.25 again because real irradiance can exceed the test condition (cold clear days, cloud-edge focusing). Wire, fuses and breakers are all sized to this 1.56×Isc design current.
Why do solar designs target only 1–3 % drop when codes allow more?+
Because PV drop is energy thrown away every sunny hour for 25 years. An extra few dollars of copper pays back quickly; at 12/24 V battery systems the drop also directly distorts charge-controller behaviour.
Is the Solar Wire Gauge Calculator free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
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