USE-2 wires and PV wires are both cables used for solar systems, but they have some major differences:

Purpose: USE-2 wires are usually used to connect power supply equipment, but they are limited to use in wet or dry environments with a maximum temperature of 90°C. PV wires have a rated temperature of 90°C and a maximum temperature of 150°C, and they are designed specifically for connecting solar modules.

Rated voltage: USE-2 wires have a rated voltage of 600V, while PV wires can have a rated voltage of 600V, 1000V, or 2000V.

Application: According to the National Electrical Code of the United States, USE-2 wires can only be used for grounded solar photovoltaic arrays, while PV wires can be used for ungrounded and grounded solar photovoltaic arrays.

Construction: USE-2 wires can usually be protected from physical damage by mechanical protection, while PV wires have thicker insulation or jackets as additional protection.

Conductor: USE-2 wires can choose solid or stranded conductors, and the conductor material can be copper, copper-clad aluminum, or aluminum. PV wires must use stranded copper conductors to ensure that their flexibility meets the requirements of the intended use.

Conductor size: USE-2 wires have a minimum conductor size of 14 AWG, but PV wires can use conductors as small as 18 AWG. USE-2 wires are generally protected from physical damage by mechanical protection, while PV wires have thicker insulation or jackets as additional protection. USE-2 wires are generally installed in places that do not rotate or are not easily damaged by mechanical forces so that they can use solid or stranded conductors, and the conductor material can be copper, copper-clad aluminum, or aluminum. PV wires must use stranded copper conductors to ensure that their flexibility meets the intended use requirements. USE-2 wires have a minimum conductor size of 14 AWG, but PV wires can use conductors as small as 18 AWG.

Insulation and jacket materials: USE-2 wires and PV wires generally use XLPE or EPCV thermosetting insulation and jacket materials, but other thermosetting materials are also occasionally used, such as CP over EP, CP, EPCV, SBR/IIR/NR, and EP. PV wires can refer to the UF cable type, but they must use a complete PVC insulation and jacket that can withstand a high temperature and humid environment of 90°C or above and the thickness must be increased by 15 mils.

Test requirements: USE-2 wires are generally installed underground or in similar environments, so they do not need a flame rating, but PV wires are installed in exposed environments, so they need to pass a flame test. However, overload tests and mechanical damage tests such as crush resistance and impact resistance are only applicable to USE-2 wires. As for sunlight resistance and low-temperature flexibility tests, USE-2 wires only need to undergo 300 hours of weathering chamber and -25°C low-temperature chamber treatment, while PV wires need to undergo 720 hours of weathering chamber and -40°C low-temperature chamber treatment to meet the more stringent specification requirements. In general, PV wires have better sunlight resistance and low-temperature flexibility than USE-2 wires, and they have thicker insulation or jacket and flame rating. In addition, they can be used in ungrounded solar photovoltaic arrays and inverters without transformers, so they are expected to become the main interconnect wires for solar modules in the future.