PV wire, also known as solar photovoltaic wire, is a single conductor wire used to connect panels in photovoltaic electrical energy systems. A photovoltaic system or solar panel is an electricity production system that captures sunlight to produce electricity through an energy conversion process. The electricity is generated by the panels and wiring is required to transmit the electricity back to the collection point or device. PV wire is a special type of wire designed for photovoltaic applications.

Purpose – PV wire, rated for 90ºC wet and up to 150ºC dry, is designed to connect PV modules. USE-2 wire is designated as an underground service entrance cable and is typically used to connect terminals on service equipment. It is limited to installation in wet and dry conditions up to 90ºC.

Both USE-2 wire and PV wire are rated for 600 V. However, PV wire is also available in 1000 V and 2000 V ratings to accommodate PV modules used in systems with system voltages greater than 600 V. According to the NEC, USE-2 wire is suitable only for grounded PV arrays, but PV wire can be used for both grounded and ungrounded PV arrays.

Construction – PV wire is equipped with a thicker insulation or jacket to provide additional mechanical protection against the physical damage that USE-2 wire is typically subject to. PV wire uses stranded copper conductors, making it flexible enough for its intended application. In contrast, USE-2 wire can use solid or stranded conductors made of copper, copper-clad aluminum, or aluminum, as it is typically installed in locations where it will not move or be mechanically damaged. The minimum conductor size for USE

-2 wire is 14 AWG, but PV wire can use smaller conductor sizes, down to 18 AWG.

Insulation and Jacket Materials – Both PV wire and USE-2 wire use thermoset insulation and jackets, typically made of XLPE or EPCV. However, other thermoset materials such as CP over EP, CP over EPCV, SBR/IIR/NR, and EP can also be used.

PV wire can also be constructed similarly to Type UF, but with an additional 15mm of 90ºC wet/dry rated integral PVC insulation and jacket.

Overall, PV wire offers superior sunlight resistance and low-temperature flexibility compared to USE-2 wire, in addition to thicker insulation or jacketing and proven flame retardancy. Given that PV wire facilitates the use of ungrounded PV arrays and transformerless inverters, its use in module interconnection is expected to increase.