Solar and PV cable: UL 4703 PV Wire and dual-rated USE-2
Array cable spends twenty-five years in the sun, so the specification is about the jacket as much as the conductor. PV Wire and dual-rated USE-2 are not the same product, and the print says which is which.
- PV Wire, UL 4703
- 1 kV to 2 kV
- Sunlight resistant
PV Wire is listed to UL 4703 and built for the DC side of an array: stranded conductor, XLPE or EPR insulation, a sunlight-resistant jacket, and a voltage rating of 600 V, 1 kV, 1.5 kV or 2 kV depending on the construction. It is rated for direct exposure and for the temperature range a rooftop or a tracker sees, which is why it is not interchangeable with ordinary building wire.
The other common product is USE-2 dual rated as RHW-2, which covers 600 V and 1 kV applications and is often used in conduit or in grounded array wiring where direct sunlight exposure is not the governing condition. A dual-rated cable carries both listings on the print. A single-rated USE-2 does not, and that difference decides whether an inspector will accept the installation. That listing is what an inspector reads before the array is energised.
System voltage drives the choice. A 1500 V DC array needs cable rated 1.5 kV or 2 kV, and a 1000 V array can use 1 kV cable. Connectors are part of the same question, because a PV connector is only rated with the cable it was listed for, and a reel whose jacket diameter is wrong will not take the connectors already on a contractor’s truck. A connector matched to the wrong jacket diameter is a problem on the roof, not in the store.
What we buy in this family
Condition and documentation decide the basis, not the family alone. These are the forms this material usually arrives in.
- PV Wire listed to UL 4703
- Dual-rated USE-2 and RHW-2
- 1 kV, 1.5 kV and 2 kV DC cable
- Sunlight-resistant XLPE insulated cable
- 10 AWG through 4/0 array cable
- Tracker and homerun cable on reels
- Partial reels with the print intact
PV Wire, USE-2 and the dual rating that decides acceptance
The two products overlap in size and diverge in purpose. PV Wire is a single-purpose product for array wiring, and its listing covers exposure. USE-2 is an underground service entrance cable that happens to be sunlight resistant in many constructions, and it is often dual rated with RHW-2 so it can also be used in conduit and in wet locations.
A dual-rated reel is the more flexible asset and generally the easier one to place, because it satisfies more specifications. A single-rated reel is not defective, it is narrower. Where a specification says PV Wire, only a UL 4703 listing satisfies it.
Sun, heat and the jacket that fails first
Sunlight resistance is a rating, not an immunity. A jacket formulated for exposure will still chalk, harden and eventually crack after enough summers, particularly on a reel stored outdoors where the outer wraps take the full face of the sun and the inner wraps are shaded. That gradient is why the first ten feet tell you more than the rest.
Heat is the other half. A reel in a steel container in July reaches temperatures well above ambient, and thermoset insulation tolerates that better than the jacket compound does. We look for cracking at the bend, a jacket gone dull and grey, and the white bloom some PVC compounds show after long exposure.
Reels, footage and the DC side of a decommissioned array
Overage from construction is the good material. A partial reel of 10 AWG PV Wire with the tag and print intact is reviewed by footage, and it moves because array work is continuous across the coastal plain. Coils pulled from a tracker after a repower are a different proposition, because the jacket has been in service and the ends have been wet.
Where this cable turns up in the two states
Utility-scale solar in North Carolina is concentrated on the coastal plain, where large flat sites and interconnection capacity made the counties east of I-95 the state’s solar belt, and in the South Carolina Midlands around Columbia and Orangeburg. Those projects are built in blocks, and a redesigned block leaves cable on reels rather than in the ground.
Distributed generation is the other source: rooftop and carport arrays on warehouses along the interstate corridors, municipal and co-op solar in the rural counties, and the array work that accompanies a plant expansion. Smaller projects generate smaller overage, usually in 10 and 8 AWG, and it sits in a container until someone decides what to do with it.
Coverage
North and South Carolina
Every city page carries the local industrial base and access notes. Start from a state hub if you are not sure which one applies.
Solar and PV cable questions
What is the difference between PV Wire and USE-2?
PV Wire is listed to UL 4703 and rated for direct sunlight exposure and the temperature extremes of array wiring. USE-2 is an underground service entrance cable, often dual rated with RHW-2 for 1 kV work. Where a specification calls for PV Wire, a single-rated USE-2 does not satisfy it, and an inspector will read the print on the jacket.
Can I use 1 kV cable on a 1500 V array?
No. The DC voltage of a 1500 V array, with temperature correction applied, exceeds a 1 kV rating. That is why 1.5 kV and 2 kV constructions exist. The rating is printed on the jacket, and a reel without legible print is a problem on any project that has to pass inspection before energisation.
Does solar cable degrade in storage?
The jacket is formulated for sunlight but not for standing in a puddle for three years. UV exposure on a reel stored outdoors will chalk and eventually crack the jacket, and moisture entering a stranded conductor through an open end travels the length of the reel. Both are visible at review if the reel is photographed honestly.
Do you buy cable from a decommissioned array?
Yes, and it is a mixed proposition. Cable that was in the ground or on a tracker has been in service for years and its jacket has a history. Cable left over from construction and never installed is material. We separate the two, and we will tell you which is which after looking at the reels rather than before.
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