What Size Cable Do You Need for a Solar Panel Array?

For a typical domestic solar array (3-4kW, 8-10A per string at Voc), use 4mm² double-insulated DC solar cable under BS 7671 Section 712. Under NEC Article 690, 10 AWG USE-2 or PV Wire is standard per Table 310.16. Solar DC cables must be UV-resistant, double-insulated, and rated for the string open-circuit voltage multiplied by the temperature correction factor.

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Quick Reference: Cable Size for Solar Panel Array (PV String Cable) by Standard

Standard	Cable Size	Conditions	Reference
BS 7671	4mm² DC	PV string cable, Section 712, UV-resistant	Table 4D1A
NEC	10 AWG	PV source circuit, NEC Article 690, USE-2/PV Wire	Table 310.16
AS/NZS 3008	4mm²	DC PV cable, AS/NZS 5033	Table 13
IEC 60364	4mm²	DC string cable, IEC 62548	Table B.52.4

Values shown are for copper conductors in typical domestic/commercial conditions. Actual size depends on installation method, ambient temperature, and cable length. Use our free cable sizing calculator for your exact scenario.

Typical Applications for a Solar Panel Array (PV String Cable)

Domestic rooftop solar
Commercial PV array
Solar carport installation
Ground-mounted solar farm

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These are general guidelines. Your specific installation needs exact calculation accounting for cable route length, installation method, ambient temperature, and cable grouping.

Cable Sizing Calculator Voltage Drop Calculator

Frequently Asked Questions

Why is solar cable different from normal cable?▼

Solar DC cable must be double-insulated, UV-resistant, and rated for outdoor exposure over 25+ years. Standard PVC cable degrades in sunlight. BS 7671 Section 712 and IEC 62930 specify solar cable requirements. H1Z2Z2-K is the standard type designation.

What size cable from panels to inverter?▼

For a typical domestic string (8-10A), 4mm² DC solar cable is standard for runs up to 30m. For longer runs or higher-current strings, 6mm² reduces voltage drop losses. Every 1% voltage drop in DC cabling reduces annual energy yield by approximately 1%.

What size cable from inverter to consumer unit?▼

The AC output cable from inverter to consumer unit depends on the inverter rating. A 3.6kW single-phase inverter outputs 16A — use 2.5mm² on a 20A circuit. A 5kW inverter outputs 22A — use 4mm² on a 25A or 32A circuit.

Do solar cables need to be in conduit?▼

Not necessarily. Solar DC cable (H1Z2Z2-K) is rated for direct exposure to weather and UV. However, conduit or trunking provides additional mechanical protection, especially on flat roofs and ground-mount installations.

What is the maximum string voltage for solar panels?▼

BS 7671 Section 712 limits DC voltage to 1,500V for commercial and 600V for domestic installations. String voltage equals panels in series multiplied by Voc (corrected for minimum temperature). Cable voltage rating must exceed the maximum string voltage.

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What Size Cable Do You Need for an EV Charger?6mm² (7.4kW) or 10mm² (long runs) (BS 7671)

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