Types of Solar Cables
The systems that create solar power are called photovoltaic (PV) systems. The most recognizable part of a photovoltaic system, the solar panel, is the mechanism that converts the sun’s energy into usable electric current. However, these power systems don’t rely on solar panels alone. Specialized solar cables play an important role in getting green energy going! There are three main types of solar cables used as a power supply cable in solar power systems: PV Wire, USE-2 Wire, and THHN Wire. These three wires having varying constructions, making them suitable for different uses.
What is PV Wire?
Solar Panel PV Wire is a very popular solar power cable. This cable is used for interconnection wiring in photovoltaic systems. Most PV Wire features XLPE insulation and either bare or tinned copper conductors. This XLPE insulation makes the wire ozone, UV, sunlight, and moisture resistant. PV Wire is an extremely durable cable, designed specifically to withstand the environmental conditions of solar power applications.
It has a maximum temperature of +90°C in wet environments and +150°C in dry applications. It comes with varying voltage ratings, with either 600V, 1000V, or 2000V ratings. PV Wire can be used as an underground service entrance wire and is appropriate for both grounded and ungrounded PV arrays. These solar cables are also suitable for use in direct burial applications due to their thick insulation. PV Wire meets UL Standard 4703.
What is USE 2 Wire?
USE-2 Wire is another type of solar cable. It is an Underground Service Wire, meaning it is designed for and should only be used in grounded PV arrays. USE-2 Wire also features XLPE insulation and is available with a bare copper, tinned copper, or aluminum conductor. It is also often dual-rated as RHW/RHH Wire. This wire shares the high heat resistance of RHH wire and the water-resistance of RHW wire. This solar cable is crush, oil, gas, and impact-resistant. USE-2 wire also has a voltage rating of 600V and a temperature rating of 90°C in both wet or dry conditions. Because of this, it is ideal for more industrial applications.
While USE-2 solar cable is crush and impact-resistant, PV wire has thicker insulation and jacket. PV Wire also has better sunlight resistance, flame resistance, and flexibility at low temperatures. This makes PV wire the best choice for ungrounded PV arrays that encounter harsher weather conditions.
What is THHN Wire?
THHN wire is also commonly used in solar applications. It is a building wire used to carry electrical currents through power applications. Like USE-2 wire, THHN wire has a voltage rating of 600V and a maximum temperature of +90ºC in dry locations. However, it only has a maximum temperature of +75ºC in wet locations. Because of this, it should never be used in applications that specifically call for USE-2 or PV wire.
If a standard specifically calls for USE-2 or PV Wire, THHN wire cannot be used. These standards account for the extra strength and resistances found in PV and USE-2 Wire constructions. While THHN wire serves virtually the same purpose as these wires, its construction doesn’t account for the severe conditions of solar power applications. Using THHN wire in these applications may result in a system failure.
| Conductor | Insulation | Voltage Rating | Max. Temperature | UL Styles | |
|---|---|---|---|---|---|
| PV Wire | Bare or Tinned Copper | XLPE | 600V, 1000V, or 2000V | 105°C Dry, 90°C Wet | UL44, UL4703 |
| USE-2 Wire | Aluminum, Bare or Tinned Copper | XLPE | 600V | 90°C Dry and Wet | UL44, UL854 |
| THHN Wire | Bare Copper | PVC | 600V | 90°C Dry, 75°C Wet | UL83, UL1063 |
As you can see, these different types of solar power cables each have their own benefits. They are all found in a generator, solar charge controller, and service grid. However, these wires must be chosen carefully because of their construction differences. All of these cables are also available in RoHS compliant versions. RoHS compliance means that the cable is free of hazardous substances, making it even greener! Choosing renewable energy cables with non-hazardous materials puts an environmentally friendly cable in an environmentally friendly application. It doesn’t get much better than that!