Solar energy is booming in the United States for a good reason.
In 2021, about 23.6 GWdc of solar power capacity was installed in the U.S., accounting for nearly half (46%) of new electricity-generating capacity. It was also the third consecutive year that solar held the largest share of new generating capacity. Of all electricity generated in the U.S. last year, almost 4% came from solar panel systems.
The United States has relied on the power of fossil fuels for decades, but there has been a concerted effort to make the energy we consume cleaner. Solar cells, also known as photovoltaic cells, are small but are packed together into solar panels, which convert sunlight into usable electricity. As more panels or modules are connected, they form arrays, and may eventually be connected to the power grid as part of a system.
Recently, the Underwriters Laboratories (UL) issued a brief overview of the solar panel market and the copper wire requirements needed to serve that industry. We took some time to brush up on the differences between PV and USE-2 wire in photovoltaic modules.
According to UL, “PV wire has superior sunlight resistance and low-temperature flexibility in addition to a thicker insulation or jacket and a proven level of flame resistance.”
Overall, only wires or cables highlighted in the National Electric Code (NEC) can be installed in modules sold in the U.S.
Single-conductor Type USE-2 cable and photovoltaic (PV) wire are both ok to use in exposed outdoor installations.
Because these installations are usually found in more extreme environmental conditions, insulation for these conductors must be sunlight resistant and rated for wet conditions. It also must be able to handle temperatures of up to 90°C.
PV wire must go through a flame test and strict sunlight resistance tests, while USE-2 must pass several abuse tests that PV isn’t subject to. USE-2 does not need to go through a flame test because it isn’t typically installed where flames might be. USE-2 also doesn’t have to meet the same standards for sunlight resistance.
Both tests are part of the UL 4703 specification requirements.
As the country inches closer toward a greener future on the back of solar energy, we could start seeing our electricity supply shift dramatically. This makes the need for high-quality PV wire more vital than ever.
A recent study by the U.S. Department of Energy Solar Energy Technologies Office and the National Renewable Energy Laboratory suggested that solar could provide up to 40% of the country’s generated electricity by 2035.
However, solar installers will need to pick up the pace to hit those goals, with an estimated deployment rate of 60 GW between 2025 and 2030.
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