Using just any type of wire in your PV system is one of the biggest errors you can make in the process of installation. Getting the right type of wire for your solar system is essential for optimal performance and safety. When choosing a solar wire for your PV system, factors like wire size, gauge number/wire gauge, and wire length are vital. Thus, we pored over various products for the said features in our search for the best solar wires.
Things to Consider
If a solar wire is undersized (unsuitably high gauge number), it will pose safety risks as it may heat up and start a fire. Also, an undersized wire would have a considerably high voltage drop, meaning it will lose a lot of power. Consequently, your battery may never get enough charge, and the system will offer inferior performance.
The longer a wire is, the higher the resistance it offers. When a wire produces a lot of resistance, less current flows through it. Consequently, less power will reach the battery bank, and the solar system will not perform optimally.
1. WindyNation
The WindyNation Solar Connectors is our top pick for good reasons. For one, it has an ampacity of up to 40 amps in dry and wet conditions. This means you get stable performance since the power loss over wide temperature ranges is low.
The WindyNation One Pair Solar Connectors are available in two gauge numbers: 10 AWG and 12 AWG. The 10-AWG comes in 13 different lengths, while the 12-AWG is available in 14 lengths. This means you get more options than you will get with the BougeRV Solar Extension Cable.
WindyNation One Pair Solar Connectors operate in the same temperature range as the BougeRV Solar Extension Cable (-40 to 194 F). It is insulated with chemically cross-linked polyethylene. While polyethylene offers marked resistance to water and dust, it does not match the effectiveness of PVC.
The polyethylene used in crafting the WindyNation One Pair Solar Connectors offers some UV resistance. But over time, it may succumb to UV degradation.
The price difference between the WindyNation One Pair Solar Connectors and the BougeRV Solar Extension Cable is insignificant and non-uniform. So, except you are getting a very long one, you would not have to bother about their prices.
While this product might be okay for connecting a solar panel to the charge controller, it may not work for the batteries. It may also be unsuitable for use as a combiner.
Pros
- It has considerable ampacity.
- It is easy to install and use.
- The 2 wire variants are available in multiple lengths, giving you enough options.
Cons
- Using a PVC material, XLPE, or CPE will offer better durability.
- It may not be suitable for use in the battery bank or as a combiner.
2. BougeRV
If you prioritize durability, then consider the BougeRV Solar Extension Cable with Female and Male Connectors.
The BougeRV Solar Extension Cable is sheathed with PVC. But on the other hand, the WindyNation One Pair Solar Connectors are sheathed with polyethylene. While polyethylene and PVC are both waterproof, PVC offers better water resistance. PVC is also more fire-resistant than polyethylene.
The BougeRV Solar Extension Cable has an ingress protection code of IP 67. So, it is significantly water-resistant and cannot be affected by dust or airborne particles.
The BougeRV Solar Extension Cable is available in 2 gauge numbers: 10 AWG and 12 AWG. The 10-AWG variant is available in 6 lengths: 6 feet, 10 feet, 20 feet, 30 feet, 40 feet, and 50 feet. The 12-AWG type, on the other hand, is available in only 10 feet and 20 feet. Well, one would expect more options for both wire sizes. But since it is a 12-AWG wire, you may not need it to come longer than 20 feet.
The BougeRV Solar Extension Cable and the WindyNation One Pair Solar Connectors have the same operating temperatures (-40 F to 194 F). However, the WindyNation One Pair Solar Connectors have a higher ampacity (up to 40 amps in wet and dry conditions).
The BougeRV Solar Extension Cable and the WindyNation One Pair Solar Connectors are UV-resistant. However, you should note that they will still get weathered by UV rays over time, albeit slowly.
Both products have about the same cost per foot. So, there isn’t a significant difference in the price you will have to pay for either. Both products are also made with pure copper, which is more suitable than aluminum in domestic solar systems.
Like the WindyNation One Pair Solar Connectors, the BougeRV Solar Extension Cable may not be okay for combiners and battery banks. But it should be fine for connecting the solar panel directly to the charge controller.
Pros
- It is durable – water-resistant, dust-resistant, and fire-resistant to some degree.
- It is easy to install.
- The 10-AWG variant comes in multiple lengths, giving you options.
Cons
- The 12-AWG variant is only available in 2 lengths, limiting your options.
- It may not be suitable for use in the battery bank or as a combiner.
What Is the Best Solar Wire?
The best wire for a solar panel system is a PV wire. PV wires offer flexibility and durability compared to the closest alternative, USE-2.
According to the national electrical code, a PV wire can be used in grounded and ungrounded systems, but USE-2 wires can only be used in grounded systems. PV wires are typically made of copper instead of aluminum. So, with them, you can expect higher conductivity, lower resistance, and relatively efficient performance.
While both PV wires and USE-2 can work in wet & dry locations, PV wires have a higher dry-rating temperature (up to 302 degrees Fahrenheit).
Apart from the above, PV wires have thicker insulation, which offers better resistance against mechanical stress. Also, PV wires are more flexible at lower temperatures, and they offer higher UV resistance and even some degree of flame resistance.
If you need wires for a PV system with a maximum voltage of over 600 volts, a PV wire will do. They come in 3 voltage ratings, 600 V, 1 kV, and 2 kV. USE-2 wires, on the other hand, have a maximum voltage rating of 600 V.
One feature common to PV wires and USE-2 wires is that the national electrical code permits direct burying.
How Do I Choose the Best Solar Wire?
Choosing a Solar Wire for Your Solar Panel
When choosing a solar wire for your solar panel, you have to consider the power rating of the system, the output voltage rating, and the distance between the solar panels and the charge controller.
The power and output voltage rating will determine the output current of the system. The output current, in turn, will determine the optimal wire size/thickness/AWG. Then the distance between the solar panels or combiners and the charge controller will determine the wire length you should opt for.
The wire size/thickness/AWG and wire length determine the safety and performance of your solar energy system. (AWG means American Wire Gauge)
Here Is How It Works
The power rating and the output voltage rating of a solar energy system determine how much current the system produces. This output current, in turn, will suggest the minimum wire size or AWG of the wire you should get.
The higher the current the system produces, the thicker the wire should be. The thicker a solar wire is, the lower its AWG rating.
Once you know the output current of your solar energy system, check for a wire size with a maximum current capacity that exceeds or matches that value. You should be able to determine that from a PV-Wire Gauge Guide such as the one below:
So, for instance, if you have a 350-watt, 12 volts system, the output current would be 350/12 = 29.2 amps. Going by the guide above, you will need a wire with an AWG of 10 or less.
Once you know the minimum thickness of the wire (maximum AWG) you need, determine the distance between the solar panels and the charge controller. This distance will determine the length of the wire you need. The wire’s length, in turn, will determine the most appropriate AWG for your PV system.
Here’s Why
The longer the wire is, the higher its voltage drop. The higher the voltage drop, the lower the power output and performance of the system. Also, longer wires are at higher risk of heating up and causing a fire. However, with a thicker wire (lower AWG), the voltage drop and fire risk are reduced.
To match the length of the wire you need to an appropriate AWG, follow the table below:
Note: the table is based on the 2% voltage drop rule.
According to the table, a 30-amp system (we approximated 29.2 to 30) using a 10-AWG wire should have a maximum length of 3.5 feet.
So, if the length of the wire you need for the 29.2 amp solar system is 5 feet, a 10-AWG wire will not be suitable. You will have to opt for an 8-AWG wire or one lower with a lower AWG. Alternatively, you may try to move the charge controller closer to the panels to shorten the length of the wire required.
When using multiple solar panels in parallel, you will need a combiner (typically 3-8 AWG wires). Combiner wire safely combines and transfers the power from each solar panel to the charge controller. If you use a combiner, the wire length described above will apply to the length of the combiner wire needed to reach the charge controller.
Choosing a Solar Wire for Your Battery Bank
Generally, the battery bank usually has the thickest wires (the wires with the lowest AWG) in a solar energy system. The battery bank needs thicker wires because the power inverter sometimes pulls more current than the solar system can supply by itself.
Typically, the batteries of a solar battery bank are connected and the power inverter with 1/0 (one-ought) wires, which have a capacity rating of up to 150 amps.
As with the wire for the solar panel or combiner, length matters when choosing a wire for your battery bank. Ensure you match the AWG of your battery bank wires with their lengths to avoid safety issues and ensure the batteries last longer.
Choosing a Cable for Your AC Devices
In many cases, the wire that connects the power inverter to the AC devices is usually either a 14- or a 12-AWG. The 12-AWG wire size has a capacity rating of 15 amps, while the 14-AWG wire has a capacity rating of 20 amps.
These two sizes are common because the input current of many household appliances falls below 20 amps. But for lower voltage drop and safer, you can opt for the 12-AWG instead of the 14-AWG.
Solar Wire Types
Like every other type of electrical wire, solar wires can either be single-stranded or multi-stranded. The single-stranded types have a single conductor in their core, while the multi-stranded types have multiple conductors.
Multi-stranded wires are usually the better option in devices or systems that experience a lot of vibration. So, if you live in an area with a lot of wind, you should get a multi-stranded solar wire. They are more durable, so they resist the wind better.
However, if you do not get a lot of wind in your region, then a single-stranded PV wire would do just fine.
Solar Wire Thickness
PV wire size or thickness is one of the most vital considerations while installing a solar PV system. It determines how much voltage drop (power loss) you get and the likelihood of the wire’s heating (safety).
The thicknesses of solar wire sizes are based on a gauge scale called the American Wire Gauge (AWG). The scale appoints a gauge number to wires based on thickness – the thicker a wire is, the lower the gauge number it gets.
The thicker a wire is the higher its amps rating, and the higher the amp rating, the lower the voltage drop and power loss.
Differentiating Solar Wires and Solar Cables
The terms solar wires and solar cables are usually applied interchangeably. Interestingly, they are not the same thing.
Solar cables are made up of two or more insulated wires enclosed in one large insulating jacket. On the other hand, a solar wire is made up of a single conductor or multi-stranded conductors, which may be insulated or bare.
Final Thoughts
When choosing a PV wire, your first consideration should be the output current of the PV system, as this indicates the wire size (wire gauge number) to get. After that, you should consider the length of the wire you will need – as much as you can, avoid using long wires.
If you ever have to use long wires, then opt for a thicker wire (a wire with a lower gauge number). This way, you will mitigate the effect of wire length on safety and performance. Once you can match the length of the wire to an appropriate gauge number, everything else becomes easier.
