Quick answer
Solar Cable is single-conductor wire built to carry DC power from solar panels while sitting outdoors in sun, heat and rain for decades. In the US the main type is PV wire, listed to UL 4703, joined with snap-together DC connectors listed to UL 6703.
It is one part of the larger wiring system. What sets it apart from ordinary building wire is its sunlight resistance, its voltage rating and the paired connectors on each end.
Quick facts
The key facts about solar cable, with sources:
- Main US cable standard
- UL 4703, Standard for Photovoltaic Wire 1
- Connector standards
- UL 6703 (US) and IEC 62852 (international) 3
- Example connector seal
- IP65 and IP68 (1 h at 1 m) when mated 3
- Mixing connector brands
- Creates a connection no test standard certified, says Stäubli 4
Key takeaways
- Solar cable is outdoor DC wire made to handle sun, heat, cold and water for the life of the array.
- PV wire is listed to UL 4703. Many PV wires are also listed as USE-2 and RHW-2, so one cable can carry several marks.
- Panels join with paired DC connectors, often called MC4-type, listed to UL 6703.
- Plugging one brand’s connector into another brand’s is a known cause of heat, power loss and fires.
- Cable choice is set by the designer and checked by the inspector. It is not a DIY swap.
What makes a cable a solar cable
Most house wire lives inside walls, out of the sun. Solar cable lives under the panels, where it bakes in summer, freezes in winter and gets wet. So it needs insulation that resists sunlight, heat and moisture without cracking.
In the US the product is called PV wire. Southwire describes its version as single-conductor "Type PV" power cable with cross-linked polyethylene (XLPE) insulation, rated 2,000 volts. Service Wire’s 600 V version lists sunlight resistance, direct burial and a cold rating of −40°C.
How the whole system is laid out, with conduit and grounding, is on the solar wiring page. Why DC needs extra care is on the direct current page. This page is about the cable and connectors themselves.
Where solar cable sits in the circuit
- Junction box on the back of each panel → two short factory leads, + and −
- Factory connectors → snap to the next panel’s leads to form a string
- PV wire with matching connectors → carries the string to a transition point
- Building wire in conduit → takes over for the run into or along the building
- Inverter → turns the DC into AC
How solar connectors work
Each panel lead ends in a plug or socket. They push together and lock, so a crew can join panels without stripping wire on the roof. The best-known design is the MC4 from Stäubli, which is why people call the whole class "MC4 connectors".
The Stäubli MC4 data sheet lists a contact resistance of 0.25 milliohm or less, IP65 and IP68 sealing when mated, a UL94-V0 flame class and a locking design. It is listed to UL 6703 and IEC 62852. Those numbers apply to a plug and socket from the same family.
Equipment makers plan around this. The Enphase IQ8 microinverter sheet, for example, tells installers to use its Q-DCC-2 adapter cable for MC4 DC connectors, rather than mixing parts.
Types of cable used in solar systems
| Cable type | Standard | Typical use in solar |
|---|---|---|
| PV wire | UL 4703 1 | Exposed DC wiring under and between panels |
| USE-2 | UL 854 2 | Underground service cable; some PV wire also carries this mark |
| RHW-2 / RHH | UL 44 1 | Thermoset building wire; often dual-listed with PV |
| Building wire in conduit | Per the NEC tables | DC or AC runs inside conduit off the roof |
| AC trunk cable | Maker’s listing | Microinverter systems, from panel to junction box |
PV wire vs USE-2: what the marks tell you
| PV wire | USE-2 | |
|---|---|---|
| Standard | UL 4703 Photovoltaic Wire | UL 854 Service-Entrance Cable |
| Made for | Solar arrays, sun-exposed | Underground service entrance |
| Voltage ratings seen | 600 V, 1,000 V, 2,000 V by product 2 1 | 600 V on the Service Wire listing 2 |
| Example dual listing | Service Wire PV: UL 44 RHW-2, UL 854 USE-2 and UL 4703 PV Wire | Same cable |
| Use in grounded or ungrounded PV | Service Wire says its PV cable suits both, per NEC 690.31(A) 2 | Check the listing and your code edition |
| Related page | Solar wiring | Rapid shutdown for roof voltage limits |
Example: reading one PV wire spec sheet
All values are from the Service Wire ServiceSolar PV 600 V sheet 2. This is how to read a cable line on a proposal.
| Spec line | Value for 10 AWG | What it means |
|---|---|---|
| Standards | UL 44 RHW-2, UL 854 USE-2, UL 4703 PV Wire | One cable, three listings |
| Voltage | 600 V | Fits systems whose maximum DC voltage stays at or under 600 V |
| Insulation thickness | 60 mils | Thicker sizes get thicker walls, up to 125 mils on the largest |
| Ampacity at 90°C wet/dry | 55 A (at 30°C ambient) | A table value before heat and grouping adjustments |
| Overcurrent limit noted | Not over 30 A for 10 AWG | The fuse or breaker cap the sheet cites |
| Temperature | 90°C wet/dry; −40°C cold rating | Range the insulation is rated for |
The designer adjusts ampacity for rooftop heat and bundling. That is why only the engineer’s plan, not the table value, sets the size on your system.
Where you will see solar cable
Under the panels. Leads and PV wire clipped to the racking. They should not touch the roof or hang in loops.
On a ground mount. Some PV wire is listed for direct burial, but routes and depth are set by code and the plan. Our ground-mount page covers that layout.
On your proposal or plan set. The cable type and size appear on the wiring diagram. Ask for the spec sheet if it only says "PV wire".
In portable kits. Off-grid and RV kits ship with PV extension cables and connectors. Our off-grid page explains those systems.
Strengths and weak points of solar cable
Strengths
- Insulation built for sun, heat, cold and water.
- Snap connectors speed installs and cut wiring errors on the roof.
- High voltage ratings, up to 2,000 V on some products 1.
- Dual listings let one cable serve more than one job.
Weak points
- Each connector is a possible fault point if crimped or seated badly.
- Rodents can chew exposed cable under arrays.
- Connector families do not safely mix across brands 4.
- Loose cable rubbing on roof edges can wear through insulation.
What the label on a cable does not tell you
A UL mark tells you a cable passed its tests. It does not tell you the cable is the right size for your circuit. That depends on current, temperature, distance and how many wires run together.
A connector’s ratings also assume it was crimped with the right tool and paired with its own family. A good part fitted badly can still fail. That is why an inspector looks at both.
Cost drivers for cable and connectors
We do not list cable prices. On a home system, cable and connectors are a small share of the total and are rolled into the install price. The drivers are run length, wire size, voltage rating, and whether the design uses home-run cables or trunk cables.
Cheap, unbranded connectors cost less up front but bring the cross-mating risk below. Lifespan is set by the listings and the install. The Southwire sheet lists 90°C continuous, 130°C emergency overload and 250°C short-circuit ratings. Our cost per watt guide shows the bigger cost picture.
How cable and connectors are chosen and checked
A licensed installer handles every step. These are the checkpoints, not instructions.
- The designer sets the maximum DC voltage and current for each string.
- The designer picks a cable type and size, and a connector family that matches the panels.
- The plan set lists them, and the permit office reviews it.
- The crew crimps any field connectors with the maker’s tool and pairs them with the same family.
- The inspector checks cable type, support, labels and connections.
Ask your installer which connector brand is on your panels and which they use in the field. If they differ, ask how the connection is listed.
Keeping cable and connectors healthy
From the ground, look for cable hanging below the array, chewed jackets and loose ties. You can ask about critter guards if animals nest under the panels.
During any service visit, ask the technician to check connectors for heat marks. A thermal camera can spot a hot connection before it fails. Book solar repair if your app shows a string producing less than its neighbours.
Warning signs and when to call a pro
Call your installer or a licensed electrician if you see any of these. Do not unplug or touch connectors:
- Melted, browned or warped connector housings.
- A string that keeps dropping out on the monitoring app.
- Arc-fault or ground-fault errors on the inverter.
- Cable lying on the roof, kinked, or rubbing on a sharp edge.
- Connectors of two different brands plugged together.
- Ordinary indoor wire used under the panels.
Safety rule
Never unplug a solar connector under load. Panels in light push DC current that can arc. Leave it to a licensed electrician.
Standards and code for solar cable and connectors
UL 4703. Underwriters Laboratories’ Standard for Photovoltaic Wire, listed on Southwire’s and Service Wire’s PV cable sheets.
UL 6703 and IEC 62852. The US and international standards for PV connectors. Stäubli’s MC4 sheet lists both. Stäubli’s product-liability statement says these standards were written for connectors of the same type family from one maker. A plug from maker A in a socket from maker B is, in its words, "a new, non-certified connection."
NEC Article 690. The National Electrical Code (NFPA 70) sets where PV wire may run. IAEI’s summary of the 2023 edition notes expanded rules in 690.31(C) for single-conductor cable, including PV wire smaller than 1/0 AWG in cable tray. Your state or city adopts the edition that applies.
Misconceptions about solar cable
- Myth All "MC4-compatible" connectors work together.
- Reality Stäubli says cross-mating often leads to failures, power loss and fires, and is not covered by the test standards 4.
- Myth USE-2 and PV wire are different cables.
- Reality Often the same cable carries both listings, plus RHW-2. Check the jacket print 2.
- Myth Thicker cable is always better.
- Reality The right size comes from the circuit design. Oversize cable may not fit the connector it must pair with.
- Myth Solar cable can be extended with any outdoor extension cord.
- Reality AC cords are not rated or listed for DC PV circuits.
Solar cable in SC, GA and VA
Cable and connector standards are national, so there is no state-specific cable rule we can verify for South Carolina, Georgia or Virginia.
What changes by state is the NEC edition that the permit office enforces and who may do the work. In South Carolina, wiring and connection must be done by a licensed residential electrician or a qualified licensed contractor 7. Ask your local building department which NEC edition applies.
When solar cable matters to you
- You are comparing quotes and one lists generic "MC4-compatible" parts.
- You are adding panels to an older system with a different connector brand. See adding panels.
- An inspector or installer flags a melted connector.
- You are buying an off-grid or portable kit and choosing extension cables.
Next steps
- Proposal analyzerCheck the equipment lines on your quote
- Solar hazard checkSpot warning signs on your array
- Workmanship warrantyWhat covers a failed connection
Questions about solar cable
What is the difference between PV wire and USE-2?
PV wire is listed to UL 4703, a standard made for solar arrays. USE-2 is listed to UL 854 for underground service entrance. Many cables carry both marks. Service Wire’s PV cable, for example, lists UL 44 RHW-2, UL 854 USE-2 and UL 4703 PV Wire on one 600 V product.
What does UL 4703 mean on a cable?
It means the cable is listed to UL’s Standard for Photovoltaic Wire. That is the US standard for single-conductor cable used in solar arrays. Southwire and Service Wire both list it on their PV cable sheets. Check the jacket print and the spec sheet to confirm.
Can I mix MC4 connectors from different brands?
No. Stäubli, which makes the original MC4, says cross-mating creates a non-certified connection and often leads to failures, power loss and fires. Its statement notes the test standards UL 6703 and IEC 62852 were written for one maker’s connector family. Ask your installer to match brands.
What is an MC4 connector?
MC4 is a Stäubli snap-lock DC connector used to join solar panel leads. The name is now used loosely for similar connectors from other makers. The Stäubli data sheet lists UL 6703 and IEC 62852 listings, IP68 sealing when mated and contact resistance of 0.25 milliohm or less.
What size wire is used for solar panels?
It depends on the circuit. The designer sizes cable from the current, the roof temperature, the distance and how many wires run together. As one reference point, Service Wire lists its 10 AWG PV cable at 55 amps at 90°C before adjustments. Your plan set shows the size chosen.
How long does solar cable last?
There is no single lifespan we can verify. Cable life depends on its ratings and how well it is supported and protected. PV wire is built to resist sun, heat and moisture. Southwire lists 90°C continuous, 130°C emergency and 250°C short-circuit ratings. Check your installer’s workmanship warranty.
Why did my solar connector melt?
A melted connector usually means a hot, high-resistance contact. Common causes are a poor crimp, a connector not fully seated, water getting in, or two different brands mated together. Stäubli links cross-mating to fires. Do not touch it. Call your installer or a licensed electrician.
Can solar cable be buried?
Some PV wire is listed for direct burial, such as Southwire and Service Wire products we checked. Whether it can be buried on your site, and how deep, depends on the NEC edition and the plan. Many ground-mount runs use conduit. A licensed installer decides.
Is solar cable the same as regular electrical wire?
No. Regular building wire is made for use inside walls or conduit. Solar cable is made to sit outdoors in sunlight and heat. It is listed to UL 4703 and usually rated for 90°C wet or dry. Indoor wire should not be used under panels.
Sources
- Southwire, SPEC 45411: Copper 2000V XLPE RHH/RHW-2 Type PV cable (UL 4703, UL 44), retrieved .
- Service Wire Co., ServiceSolar (PV) RHW-2 600 Volt Copper spec sheet, retrieved .
- Stäubli Electrical Connectors, MC4 connector data sheet (Photovoltaic main catalog excerpt), retrieved .
- Stäubli Electrical Connectors, Cross-mating of PV connectors: product liability statement, retrieved .
- Enphase Energy, IQ8M and IQ8A Microinverters data sheet (DSH-00243-3.0-EN-2024-12-10), retrieved .
- IAEI Magazine (J. Wiles), 2023 National Electrical Code and Photovoltaic Power Systems, 23 March 2023, retrieved .
- SC LLR, Residential Specialty Contractor registration (Solar Panel Installer) application package, retrieved .
Expert review
Written by the HyreSolar Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Cable ratings from Southwire SPEC 45411 and the Service Wire ServiceSolar PV 600 V sheet; connector ratings from the Stäubli MC4 data sheet; cross-mating position quoted from Stäubli’s product-liability statement (a manufacturer view); NEC changes from IAEI’s 2023 summary; SC licensing from the LLR package via sc-local/facts.js.
No prices or lifespans are given.
Suggest a correction. We fix errors and say what changed.