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Solar Wiring Guide: The Basics of Solar Cables – Cable Types, Width, Length, and Installation

Welcome to our ultimate solar wiring guide. This guide will cover all the main benefits of solar cables and information such as voltage, power, current, string configuration, and other essentials you need to understand solar wiring better. 

Solar wires are some of the basic components of photovoltaic power generation. They carry out the job of connecting solar panels to other electrical components is the solar rig. Well, solar cables are highly weather-resistant and can endure high temperatures.   

The following are the main benefits of solar cables:

  • Heat-Resistant for High Temperatures up to 125c.
  • UV Light Resistant.
  • Water-resistant.
  • Easy to Connect to Other Panels.

To install solar cables, you need to have basic knowledge regarding string configuration. There are only two ways to set strings (series & parallel), which we will distill below.

Solar cables are resistant to UV light and can withstand heavy pressure. Depending on your local jurisdiction, you may have specific rules regarding the grounding of solar power and electric shock protection to abide by.

There are two critical choices for the wiring system of solar panels: The size of the wire and the connection method. In this solar wiring guide, we are going to look over the basic stringing/connecting principles between the inverter and the solar array.

The most popular ways to string solar panels are in parallel or in series. 

Solar Wiring Guide – Overview

Solar wires are a complex subject. We are not going to analyze the details in this guide, but if you are new to the solar wiring industry and you want to learn about the basic principles of wiring solar panels, this guide will serve as your introduction and help guide you through the basic concepts. 

When it comes down to solar wire selection, selecting the adequate wire for the job is essential. The main difference in solar wires is in size (length & width). You need the right size in order to make sure your solar system is working adequately and does not cause disruptions in the current.

Example: If the solar wire is too small for the solar PV system, the battery bank might not charge adequately, and this can cause your electronics to malfunction.

Single Core and Multi-Core Solar Cables

Photovoltaic cables vary based on the conductor type, and they are sometimes called “solar panel wires” or “electrical wires,” but they are essentially the same. Solar wires can be differentiated by their single metal wire core or their multi-wire core.

If the solar wire has single metalcore, it is a “single-stranded conductor.” If the solar wire has multiple cores, it is simply a “multi-stranded conductor.”

Of course, the single-stranded conductor and multi-stranded conductors are the two main types of solar cables. The single-stranded version is generally good for PV panels, while the multi-stranded version is also ideal for machines/items that receive constant vibration such as cars, trains, boats, and other vehicles. 

Solar cables are mostly from a single strand conductor type, and these are also the most common wires for solar panel/home use (including domestic wiring purposes). 

Solar cables are indeed capable of withstanding heat. However, they may not be ideal if the area receives constant heavy weather such as rainfall and high winds/hurricanes. In the latter case, a multi-stranded conductor is the best way to ensure cable life. 

solar cable types

Solar Cable Amp Ratings

In order to give us an idea of their performance capability, solar cables have their own “rating,” which is measured in amps. That means if the solar power system has a certain amount of amps, the wire has to provide a safe passage for that energy.

The amp rating of a solar wire determines the number of amps the wire can support at a maximum, and this amount should not be exceeded.

Example: If you have a powerful solar system with a high amp rating, you are also going to need the wire to match (usually powerful solar systems require thick solar wires).

If the system produces six amps, you will need a 6 amp solar wire to transfer the current to the system at a minimum.

Pro Tip: Always go beyond the solar system rating to make sure the wire can handle the current. If your solar system has six amps, opt for an 8 amp or a 10 amp solar wire.

If you misread the amps and you buy a wire that has fewer amps than what your solar system produces, this will cause the voltage to go under, and your solar panels will heat up and potentially start burning.  

Be cautious because if you get the rating wrong, you can cause permanent damage to your solar set up or even a house fire.

Apply caution when you are handling solar cables and always be mindful of the output. Installing cables is similar to plumbing; if there are too many amps flowing, the pipes will burst from the pressure.

So, you need a big wire that can handle the amps flowing out of your solar system. 

Solar Cable Width 

What is the ideal thickness of the wire, and does it matter for the safety of the solar system? Thick wires are more powerful, and they are more expensive than slim wires.

You have a few options in regard to the width/thickness of the wire. When you are starting out, you have two options to go for. Get a medium-thick solar cable that can handle huge amp power. Or get an even thicker wire. That can offer you better safety even in case of a power surge. 

Yes, in a surge situation, your system will not get any damage. It is because the thick cable can handle extra amps.

Hence, the best approach is to buy the thickest wire possible. Then, you can use that wire as the main wire for the AC breaker of the solar system. We recommend using a solar wire calculator to determine the size of the solar cable you need.

Solar Cable Length

The length of the wire also has an impact on solar performance. You not only have to take into account the power rating of the wire, but you should also consider the length.

In essence, if your solar wire is longer than average, then you are also going to have to make sure the wire has a higher amp power.

If you fail to mind the length, you risk experiencing a voltage drop, which can also lead to overheating and a fire.

If you have a 15 amp appliance, and then you use a 15 amp wire that is very lengthy, there is a risk of voltage drop. In this case, you have excess power to deal with. And it is ideal to buy a 20-25 amp wire to go.

The rule is this: The longer your wire, the more power you need. You need a wire with high amp ratings to make sure the voltage remains consistent. It will not also end up in voltage drops. The best approach to this is to get the thickest wire you can get. If the wire is thick, it is going to be more likely to handle the excess current.

Despite the higher initial cost, this is the right way to go. It is because you are investing in the long term – especially if you are dealing with clients who rely on you for wiring.

As a general rule of thumb, you want to add a 30-40% safety margin to the wire. 

Example: If you have a solar panel that produces ten amps, you can deduct 30-40%. And add that amount to the total amount you need for the wire. Hence, to stay on the safe side, you will need a wire that can support 13-14 amps. 

Serial Solar Cable Installation

Solar wires can be interconnected in a “series” by lining panels next to each other in a line. Similar to battery on other electronics, you will find that the batteries on solar panels have negative and positive inputs where you connect the solar wires.

When you are choosing a series mode, you basically have to run the solar wire from the positive terminal on one solar panel to the negative terminal on the next solar panel.

This is called “stringing” in series. When you choose to string the panels in series, each solar panel adds to the total voltage of the string – but the current remains the same. The current remains consistent throughout the entire string, and it is reduced to the panel with the lowest current.

The only downside to stringing solar panels in a series is that if you have a shaded panel, it can reduce the current of the whole string.

solar cable installation

Parallel Solar Cable Installation

Solar wires can also be installed in a parallel string, but this method is not as popular, and it is complex. To connect the solar panels in a parallel string, you must connect the positive terminals of the panels on one string to one solar wire. Then, repeat the same for the negative terminals and connect them all to another solar wire. 

Instead of interconnecting the panels, you take the positive terminals and connect them to one solar wire. And repeat the same for the negative terminals. The difference here is that each additional panel will increase the current (amp) of the circuit. Meanwhile, the voltage (V) will remain consistent (equal to the voltage of individual panels).

The upside of parallel stringing is that if you have one shaded panel, the others will not be affected, and the panels continue functioning normally.

Hope you have enjoyed our solar wiring guide. Share your thoughts below.

Image Courtesy: ZW-Cable.Com

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