Photovoltaic (PV) wire is a type of single-conductor electrical cable specifically designed for use in solar power systems. It is primarily used to connect solar panels to combiner boxes, inverters, and other balance-of-system components. PV wire must operate reliably in harsh outdoor environments for 25 years or more, so its construction, insulation materials, and certifications are more demanding than those of ordinary building wire.Structurally, PV wire typically consists of a stranded copper conductor for flexibility, surrounded by one or more layers of insulation and jacket material. The conductor is often tinned copper to improve corrosion resistance, especially in moist or coastal environments. Stranding reduces the risk of metal fatigue when the cable is exposed to vibration, thermal cycling, or movement of mounting structures.The insulation and jacket are usually made from cross-linked polymers such as cross-linked polyethylene (XLPE) or similar materials. Cross-linking improves thermal stability, abrasion resistance, and mechanical strength. PV wire is required to be sunlight-resistant, meaning it can withstand long-term ultraviolet (UV) radiation without cracking, becoming brittle, or losing dielectric strength. It is also generally rated for wide temperature ranges, often from -40°C up to 90°C or 105°C in wet or dry conditions.Electrically, PV wire is designed for higher system voltages common in modern solar arrays. Typical direct current (DC) voltage ratings include 600 V, 1000 V, and 1500 V, depending on the standard and application. The cable must also meet flame-retardant and smoke requirements to reduce fire hazards, especially in building-integrated or rooftop systems.In addition to outdoor durability, PV wire is often rated for wet locations and direct burial. This allows it to be run through conduit, exposed on rooftops, mounted on racking, or buried underground without additional mechanical protection, as long as it is installed according to electrical codes. Many PV wires are also rated for use in cable trays and can withstand mechanical stresses from installation and maintenance.Standards and certifications govern the design and performance of PV wire. In many markets, PV wire must comply with specific photovoltaic cable standards that address long-term aging, ozone resistance, cold bending, insulation integrity, and electrical properties under elevated temperatures. Compliance ensures that the cable will perform safely and reliably over the lifetime of the solar installation.Proper selection of PV wire involves considering conductor size, voltage rating, temperature rating, insulation type, environmental exposure, and installation method. Undersized or inappropriate cable can lead to excessive voltage drop, overheating, or premature failure. When properly specified and installed, PV wire contributes to efficient power transmission, reduced system losses, and long-term reliability of solar power installations.