What Makes Photovoltaic Wire and Cable Different from Normal Cables? PV Wire vs. USE 2
With the recent increase in the use of solar panels, the sales of photovoltaic wire and cable skyrocketed. However, since solar cables are still a recent invention, they face a lot of misunderstandings. What are the unique characteristics of a photovoltaic cable? Why can you not just simply use any cable with your solar panel and call it a day? What are other cables allowed for solar panels? Read this blog to find out.
What is so special about PV wires?
Solar PV photovoltaic cables are designed exclusively for interconnections in photovoltaic solar power systems. They are one of the newest cables on the entire market as they have only been used for less than 15 years. They are flexible, moisture, sunlight, and flame-resistant. These cables behave extremely well in very hot temperatures. Solar PV photovoltaic cables are used throughout the entire lifespan of the solar panel, which is typically 25 or 30 years, and the manufacturer typically offers you a warranty for this entire time. Solar PV photovoltaic cables are installed specifically with solar panels in mind, so their design always reflects the latest trends and innovations in the solar industry. Photovoltaic Wire comes in different voltages and may have a copper or aluminum conductor.
PV Cables vs. Regular DC Cables: Why Cannot I Use Anything in My PV Panel?
Unlike your typical DC cables that come with PVC insulation, PV cables usually have an XLPE insulation with excellent resistance to sun and weather, as well as extreme temperatures. Also, the regular DC cables only last between five and eight years with the best maintenance. This is unacceptable for solar panels that are designed to last a very long time. Therefore, the National Electrical Code prohibits using just any cable in your solar panel. The only two options you really have are PV wire and USE-2 cables.
PV Photovoltaic Cables vs. USE-2 Cables
While photovoltaic wires are desired for solar panels, they are not the only type of cable that can be used there. According to article 690 of the National Electrical Code, which is dedicated to the wiring of the photovoltaic systems, PV wires and USE-2 (Underground Service Entrance) are both permitted to be used outdoors in the photovoltaic systems. This means that you are technically not required to use photovoltaic cable and wire for your solar system and can get away with using underground service entrance cables instead. USE-2 have been a predecessor of photovoltaic cables in solar systems way before they became popular. PV wire made a debut in the 2008 edition of the NEC and has not been used on a large scale before that.
So, what are the differences between the two, and when should you use one over the other? Let's find out.
Differences between PV and USE-2
- PV wire has been developed specifically for interconnections in photovoltaic modules and has no other purpose. USE-2, however, is designed for underground service entrance, utility, direct burial, and general wiring applications. The solar panel is only one of many places where USE-2 can be used.
- USE-2 comes with a 600 V voltage rating only, while photovoltaic cables are available in a variety of cable ratings, including 600 V, 1000 V, and 2000 V. For high-voltage solar panels rated 2000kv, you can only use photovoltaic cables.
- USE-2 has a temperature rating of 90°C both for wet and dry conditions, whereas PV wire can sometimes be rated 150°C. Do not utilize USE-2 if your solar project has extreme temperature requirements.
- Photovoltaic cables are always flexible because they have stranded conductors, while not all USE-2 cables are rated for flexibility. Naturally, you should go for a flexible USE-2 if you are planning to use one in your electrical project.
- You cannot use USE-2 in ungrounded photovoltaic arrays; this is the task that only PV wire can handle because service entrance cables can only be used in grounded systems.
- Photovoltaic cables are available in small gauges, while the size of USE-2 starts from the 14 AWG only. Do not buy USE-2 if your photovoltaic system calls for small-sized cables.
- USE-2 has better crush resistance characteristics, whereas photovoltaic cables have superior resistance to flames because they are required to pass the VW-1 test before entering the market.
Similarities between PV and USE-2
- Both USE-2 and PV wire are resistant to sunlight, high temperatures, and moisture, even though photovoltaic cables have better properties when it comes to resistance to the former two.
- Both USE-2 and PV typically have an XLPE insulation, though the insulation of a photovoltaic cable is usually several inches thicker for superior protection. Though less common, EPR/CPE insulation is also a potential option for both cables. The properties are similar.
- Both USE-2 and PV wire can be directly buried without the need for extra protection per NEC. However, some photovoltaic cables are not rated for direct burial, and it is best to check with the manufacturer before installing.
- Both types of cable pass UL 4703 Standard for Photovoltaic Wire.
These differences and similarities should be the ground to choose which cable you need in your solar panel. For the best result, consider the temperature requirements of your solar project, whether your system is grounded or ungrounded, and what are the voltage requirements.
In general, PV wire is now used more frequently in exposed solar panels, whereas USE-2 is still used underground. In ungrounded systems, electricians now exclusively install PV wire. In general, photovoltaic cables are a more modern and all-around acceptable cable for your PV system, but USE-2 is still widely used, especially if you are looking to cut the overall cost of your electrical project. At Nassau National Cable, we sell a large variety of solar wires and cables, including Copper PV Solar Photovoltaic Cables with various voltage ratings, Aluminum 2KV Photovoltaic Cables, Aluminum USE-2 cables, and Copper USE-2 cables at the best prices in the industry. If you are not sure whether you want a cable with a copper or aluminum conductor, use this blog as your point of reference.
