How PV Wire and USE-2 Wire Enable More Dependable Solar Power

Kelly Benjamin
February 2, 2022

Commercial and industrial properties all over the world are tapping into solar power more than ever before. And with good reason. A rooftop solar or photovoltaic (PV) system is designed to:

  • Convert sunlight into electric current through a higher state of energy
  • Run silently with no moving parts and no environmental emissions
  • Recoup manufacturing and installation energy within two years
  • Provide 95% of net clean renewable energy over a 30-year timeframe

Environmental experts consider PV energy installations to be cleaner, less expensive sources of electricity.

PV Systems Need Wire and Cable Made for Solar Power

As interest in solar energy installations grows, organizations like the American National Standards Institute (ANSI) and the Electrical Safety Foundation International (ESFI) have adopted standards that help organizations in the United States install electrical wiring in solar power systems much more safely. These standards are recommended in the National Electrical Code (NEC), which is part of the National Fire Code published by the National Fire Protection Association (NFPA).

In 2008, the NEC started to list only two options for solar wiring that are stronger, more efficient, and the safest for commercial and industrial use: 1) PV wire and 2) USE-2 wire. As a result, manufacturers like Performance Wire and Cable, Inc. are providing this improved technology that’s made to benefit solar system installations.

Wiring used in both grounded and ungrounded solar energy installations must be designed for long-lasting protection against the elements, with excellent resistance to all environmental conditions including UV radiation, wind, weather, high-temperature fluctuations, and moisture. For instance, photovoltaic wires usually have XLPE (cross-linked polyethylene) insulation, a thermoset, zero halogen insulation that also provides flame retardance. This wiring can be used for the entire life of a solar panel, which can last 25 to 30 years. Although standard DC (direct current) cables often have PVC (polyvinyl chloride) insulation, they only last between five and eight years, even with robust maintenance. Standard DC wiring would have to be replaced more than once during the lifespan of a solar panel, in addition to not being rated for use in one by the NEC.

Advantages of Both PV Wire and USE-2 Wire for Solar Applications

One of the newest options on the market, photovoltaic (PV) wiring is designed specifically for use in solar energy systems and has been around for about 15 years. Its predecessor is USE-2 (Underground Service Entrance) wiring, commonly dual-rated as RHH/RHW-2 wire, and has uses other than solar energy systems.

Both PV wire and USE-2 wire:

  • Are resistant to sunlight, high temperatures, and moisture
  • Have XLPE insulation
  • Can be directly buried without extra protection, although some PV wire is not rated for direct burial
  • Pass UL 4703 Standard for Photovoltaic Wire

Which Should You Choose For Your Solar Energy Installation?

Before deciding on the wiring for your solar project, determine:

  • whether the system is grounded or ungrounded
  • voltage requirements
  • temperature requirements

Then consider the differences between PV wire and USE-2 wire to help you decide which is best for your installation:

  • PV wire is made specifically for photovoltaic systems and has no other purpose. USE-2 wire is used in solar panels and can also be used for underground service entrance, utility, direct burial, and general wiring applications.
  • PV wire is available in cable ratings that include 600 V, 1000 V, and 2000 V. USE-2 wire is only rated 600 V.
  • PV wire can sometimes be rated 150°C both for wet and dry conditions and extreme temperature requirements. USE-2 wire has a temperature rating of 90°C and is not as suitable for extreme temperature requirements.
  • PV wire stays flexible with stranded conductors, whereas not all USE-2 wires are rated for flexibility.
  • PV wire is made for ungrounded photovoltaic arrays. USE-2 wire is made for grounded systems.
  • PV wire is available in smaller gauges. USE-2 wire starts from the 14 AWG only.
  • PV wire has better flame resistance. USE-2 wire has better crush resistance.

Request a Quote

Performance Wire and Cable works with companies of all sizes to help you select the best quality wire and cable products that meet your custom needs. Request a free quote today!

If you have questions, email or call (315) 245-2594. One of our knowledgeable staff members will be happy to help.