USA Market — Solar BOS Hub / PV Wire
PV Wire Supplier
for the USA
UL 4703-listed single-conductor PV wire for US rooftop and ground-mount solar. Available in 12 AWG and 10 AWG (4mm² and 6mm² equivalent), 600V and 1000V DC, XLPE insulation. NEC 690.31 compliant. Section 301 tariff explicitly included in all landed-cost estimates.
UL 4703 PV Wire for the US Market
The US solar market specifies PV wire per UL 4703 — the UL listing standard for single-conductor outdoor photovoltaic wire. This differs from the European and Australian standard IEC 62930 (which covers H1Z2Z2-K cable). Both standards produce similar XLPE-insulated, UV-resistant single-conductor solar cable, but US Authorities Having Jurisdiction (AHJs) typically require the UL 4703 listing mark, not IEC certification. OmniSol sources UL 4703-listed PV wire from certified Chinese manufacturers.
US string wiring is specified in AWG (American Wire Gauge) rather than mm². 12 AWG (approximately 4mm²) and 10 AWG (approximately 6mm²) are the dominant sizes for residential and commercial string wiring. NEC 690.31 allows UL 4703 PV wire to be installed as exposed single-conductor cable on solar racking without conduit, simplifying rooftop array wiring significantly compared to conduit-based methods.
The key procurement variable for US buyers is Section 301 tariffs. PV wire classified under HS 8544 carries an additional 25% Section 301 duty on top of the ~5% MFN rate — approximately 30% total. OmniSol includes this in all US preliminary quotations. Even at a 30% total duty, Chinese UL 4703-listed PV wire typically delivers a meaningful cost advantage over domestically produced equivalents.
UL 4703 PV Wire — AWG Size Reference
Ampacity figures at 30°C base (NEC 310.15) and at 75°C equivalent ambient (derating factor ~0.77 for rooftop conduit in direct sun). Apply NEC 310.15 correction factors for your specific installation conditions.
| AWG | Metric (≈) | Voltage Rating | Ampacity @ 30°C | Ampacity @ 75°C | Typical Use |
|---|---|---|---|---|---|
| 12 AWG | ~4 mm² | 600V / 1000V DC | 20 A | 15 A | Standard residential string wiring |
| 10 AWG | ~6 mm² | 600V / 1000V DC | 30 A | 23 A | Higher-power modules, longer string runs |
| 8 AWG | ~10 mm² | 600V / 1000V DC | 40 A | 31 A | Combiner-to-inverter homerun wiring |
| 6 AWG | ~16 mm² | 600V / 1000V DC | 55 A | 43 A | High-current homeruns, DC disconnect to inverter |
NEC requires 125% of module Isc for continuous current. Apply correction for ambient temperature and bundling per NEC 310.15. Confirm final sizing with a licensed solar electrician or PE.
US-Specific PV Wire Considerations
UL 4703 vs IEC 62930 (H1Z2Z2-K)
The US market uses PV wire per UL 4703, not H1Z2Z2-K per IEC 62930 / EN 50618. Both are XLPE-insulated single-conductor cables rated for outdoor PV applications, but UL 4703 carries the UL certification mark required by most US AHJs. OmniSol sources UL 4703-listed wire from Chinese factories that have obtained UL certification — confirm UL listing with the specific project AHJ before ordering.
AWG vs mm² — both are acceptable
NEC permits both AWG and metric (mm²) conductor sizing. AWG is the traditional US designation; many solar contractors specify 12 AWG or 10 AWG. Equivalent metric sizes (4mm² and 6mm²) are acceptable per NEC 310.106(A) if the conductor has the same or greater cross-sectional area. Chinese-manufactured PV wire is often sized in mm² — confirm the actual cross-section matches or exceeds the AWG equivalent when substituting.
Temperature derating for rooftop installations
NEC 310.15(B)(2) requires ampacity correction for ambient temperatures above 30°C. Rooftop conduit in direct sun can reach 60–80°C — significantly higher than the 30°C base ampacity table. NEC 310.15(B)(3)(c) provides additional derating for conduit run exposed to direct sunlight on rooftops. For exposed PV wire on racking (no conduit), the ampacity is typically calculated using a 90°C ambient on the sunny side of the array. OmniSol's voltage drop calculator includes US temperature correction factors.
Rapid shutdown wire routing (NEC 690.12)
For string inverter systems requiring module-level rapid shutdown, the PV wire between the rapid shutdown device and the array boundary remains at full DC voltage until the initiator activates. Wire routing and labelling must comply with NEC 690.12 and the specific rapid shutdown device manufacturer requirements. For MLPE systems (microinverters / DC optimizers), string wire is typically replaced by lower-voltage DC or AC wiring — confirm wire type requirements with the MLPE vendor.
Section 301 Tariff: ~30% Total Duty on PV Wire
PV wire from China (HS 8544.42 / 8544.49) is subject to Section 301 List 3 tariffs of 25% plus the standard MFN rate of ~5%, bringing the total effective duty to approximately 30% on CIF customs value. OmniSol's US preliminary quotations include a landed-cost breakdown showing FOB price, ocean freight, and all US duty charges. Even with this tariff, UL 4703-listed Chinese PV wire lands at a significant discount to US domestic pricing. Confirm final HS classification and duty rate with your licensed customs broker.
What to Specify When Ordering PV Wire for US Projects
AWG size required
12 AWG, 10 AWG, 8 AWG, or 6 AWG — or specify mm² equivalent
Voltage rating
600V DC or 1000V DC (confirm with your inverter specs)
UL 4703 listing required
Confirm whether AHJ accepts IEC-listed equivalent or requires UL 4703 mark
Conductor colour
Red (positive) and black (negative) are standard US convention per NEC 690.31
Total reel quantity
500ft or 1000ft reels standard — specify total footage per AWG
Destination port and Incoterm
LA/Long Beach, Seattle, Savannah, Houston, Port Newark — FOB or CIF
Project type
Rooftop residential, rooftop commercial, or ground mount (affects NEC article and rapid shutdown applicability)
Rapid shutdown method
MLPE (module-level) vs string-level initiator — affects wire quantity estimate
NEC 690.31 Installation Reference
Where PV wire (UL 4703) can be installed without conduit
- On solar racking, secured and supported per NEC requirements
- Exposed wiring within the array boundary (between modules)
- Run inside extruded railing channels (wire management)
- On rooftop surfaces not subject to physical damage
Where conduit or cable protection is required
- !Inside buildings and attics (interior wiring)
- !Underground runs (conduit or listed underground cable)
- !Areas subject to physical damage (vehicles, foot traffic)
- !Within 6 inches of the rooftop in some AHJ interpretations
Size your US PV wire with the voltage drop calculator
Enter string voltage, Isc, AWG or mm², and run length — includes NEC temperature correction and 2% max voltage drop check. AWG to mm² conversion built in.
Need more than PV wire?
The Solar BOS Supplier USA hub covers the full balance of system — PV wire, UL 6703 MC4 connectors, DC MCBs/MCCBs, NEMA combiner boxes, distribution boards, LiFePO4 storage, and mounting systems. One inquiry, one shipment.
Frequently Asked Questions
What is UL 4703 PV wire and why is it required in the US?
UL 4703 is the UL listing standard for single-conductor photovoltaic wire used in solar installations. It specifies cross-linked polyethylene (XLPE) or equivalent insulation rated for outdoor exposure, UV resistance, 90°C wet/dry temperature rating, and either 600V or 1000V DC ratings. Most US Authorities Having Jurisdiction (AHJs) require UL 4703-listed PV wire for permitted rooftop and ground-mount solar installations. This differentiates the US market from Europe and Australia, where IEC 62930 / EN 50618 (H1Z2Z2-K) is the equivalent standard. OmniSol can source UL 4703-listed PV wire from Chinese factories that hold UL certification.
What AWG sizes are commonly used for residential and commercial PV wire in the US?
The most common AWG sizes for solar string wiring in the US are 12 AWG (approximately 4mm²) and 10 AWG (approximately 6mm²). 12 AWG is used for lower-current residential strings and for homerun wiring where current is within its ampacity after derating. 10 AWG is standard for higher-power commercial modules and longer string runs where voltage drop is a concern. 8 AWG (approximately 10mm²) is used for homeruns from combiner boxes to inverters on larger commercial systems. Metric sizes (mm²) can be substituted if the conductor has equivalent or greater ampacity.
How does NEC 690.31 govern PV wire installation methods?
NEC 690.31 allows UL 4703-listed PV wire to be installed as single-conductor cable without conduit in rooftop and array wiring applications, provided it is protected from physical damage, secured, and supported per NEC requirements. PV wire may be run exposed on racking where it is not subject to physical damage. Where PV wire is installed in interior spaces, conduit or cable protection is required. For underground runs, PV wire must be installed in conduit or as a listed underground cable type. NEC 690.31(G) addresses the specific requirements for PV source circuits using PV wire in arrays.
Does NEC 690.12 rapid shutdown affect PV wire selection?
NEC 690.12 rapid shutdown requires rooftop PV systems to de-energise to 30V or less within 30 seconds. For PV wire selection, rapid shutdown affects two areas: first, the wiring method between modules and the rapid shutdown boundary (typically the roofline or array boundary) must be compatible with the rapid shutdown system used; second, if MLPE (microinverters or DC optimizers) is used to achieve rapid shutdown at the module level, the AC or DC output wiring may differ from standard string wire sizing. The PV wire itself (UL 4703) remains the same listing standard regardless of rapid shutdown method — what changes is the system architecture and where the wire is run.
What Section 301 tariff applies to PV wire imported from China?
PV wire (insulated electrical conductors) is classified under HS 8544.42 or 8544.49 for US imports. This falls under Section 301 List 3, which carries a 25% additional duty on top of the standard MFN rate of approximately 5%. The total effective duty rate is approximately 30% on the declared customs value. Despite the tariff, UL 4703-listed Chinese PV wire typically lands in the US at a significant discount compared to domestically produced or European-sourced wire. OmniSol includes the Section 301 tariff in all US preliminary quotations for accurate landed-cost comparison.
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Tell us your project type (rooftop / ground-mount), AWG sizes needed, total footage, and destination port. We'll confirm UL 4703 listing availability, Section 301 tariff impact, and return a landed-cost preliminary quotation within 24–48 hours.