Can You Use Solid Wire For Solar Panels? (A Brief Solar Panel Wire Guide)

Wiring connects the components of a solar system. Solid wire is one of two types of conductors or wire as it is more commonly called, used for solar panels. Stranded wire is the alternative option.

Putting together your solar panel system yourself can save up to 15% on labor costs. But DIY can get a little complex without the right information. In this article, we introduce the different types of wire used for solar energy systems.

We will compare the two main options, solid versus stranded, as well as cover other solar basics you should know when wiring a solar panel system together. Is aluminum better than copper wire? Read on to find out.

What Kind Of Wire Is Used For Solar Panels?

Solar panels are connected with wire made from either copper or aluminum. Copper is the most common material. Copper is more popular as it has better conductivity. Aluminum is the less used alternative because it has a lower conductivity.

But what do we mean when we say copper has better conductivity and why does it matter for your solar panels?

Conductivity is the ability of a conductor to pass or carry current. When we say copper has better conductivity, we mean it carries current better or allows more current to flow through. An improved conductivity means your solar panels can relay more of the electricity they generate to your appliances.

Aluminum is a cheaper alternative conductor to copper. However, the savings you make quickly disappear as the aluminum needs to be larger to compensate for the poorer conductivity. Generally, it’s better to go with copper than aluminum. Source

USE-2 wire

These are two copper connector wires that come pre-installed on the back of a solar panel. USE-2 wires are used to connect solar panels together or directly to an inverter or battery.

PV wire

PV wire is a double-insulated conductor that connects to a load. As they have two layers of insulation, PV wire is thought to provide more protection compared to single-insulated USE-2 wire. PV wire is the only wire you are allowed to use with transformerless inverters if the wire is not in a conduit and on the roof.

Can I Use Regular Wire For Solar Panels?

Using regular wire for solar panels is not advisable. Wires in PV systems are exposed to outside weather. They are designed to be heat resistant, withstanding temperatures of up to 90 degrees Celsius. They are also designed to be water resistant so they don’t easily experience corrosion.

Solar panels are meant to last for up to 25 years. In practice, solar panels can last for 30 or even 40 years in some cases. You want to use wire that can stand up to heat and moisture without burning or corroding over a long time.

Solar wiring carries a lot of current and is exposed to direct sunlight and rain. At the very least, you need to use wire designed specifically for outdoor use. You will get a more efficient system, longer lifespan, and less of a safety risk to yourself and your system from using the right wiring.

There are also building codes and regulations you need to follow that specify what wires are permissible. If you use wiring outside those given parameters, you may find yourself in violation of your local building codes.

Is Solid Wire Better For DC?

Either solid wire or stranded wire will work well for both AC and DC. Both types of wires offer up some specific advantage over the other. For example, stranded wire is more flexible than solid wire while solid wire is typically cheaper than stranded wire.

The debate between which is better between solid and stranded is one unlikely to be resolved anytime soon. But what is solid and what is stranded wire and how do they compare against each other?

Stranded wire

Stranded wire is a bundle or strands of wire. In the U.S the measurement of the wire will be given as two digits A/B as in a 7/32 wire. The first digit is the number of strands in the wire while the second digit is the gauge or thickness of the wire.

Pros of stranded wire

Stranded wire has several pros including:

• It’s more flexible. This is especially useful where the wire needs to be bent, twisted, or routed around corners or angles.
• More heat resistant. The gaps between the strands of wire create a cooling effect so stranded wire is less prone to overheating.

Cons of stranded wire

Stranded wire does have a few shortfalls.

• More expensive.
• Higher corrosion when used outdoors.
• Higher voltage drop, meaning they carry less current compared to a solid wire of the same thickness.
• The connection of strands of wire around terminals is more difficult compared to one solid wire.

Also, we highly recommend that you check out our post “Can You Short Out A Solar Panel? What Happens If You Do & How To Deal With It !“

Solid wire

A solid wire as the name suggests is just one solid wire wrapped in insulation. A solid wire is simply measured by its thickness or gauge. Unlike a stranded wire which has two digits, it has one.

Pros of solid wire

A solid wire offers up several advantages over a stranded wire.

• It’s cheaper than stranded wire.
• Carries more current or has a higher ampacity compared to a stranded wire of the same thickness.
• Less corrosive in outdoor applications.
• Easier to connect around the terminals in your battery or inverter.

Cons of solid wire

On the negative side here’s what you get with solid wire.

• Less flexible than stranded wire so might not be suitable where you have sharp bends and corners.

Which should you use, solid or stranded? It all depends on your specific needs. If you need to run a lot of wire and you want to avoid having your costs inflate you might want to opt for solid wire.

If on the other hand, you need to work around bends and angles in your design, you might be better off with stranded wire.

Do Solar Panel Wires Need To Be In Conduit?

Conduit is not a strict requirement but it protects from heat, moisture, and ultraviolet light which can all wear out the wiring in a solar panel system. It is an added layer of protection after the insulation that already covers the wire.

There are different types of conduits you can use from PVC to metal conduit. PVC is the most popular choice for most installations because it is the cheapest. Source

We also highly recommend that you check out our post “What Happens If A Solar Panel Is Not Connected To Anything? What To Do!“