What gauge wire for 100w solar panel?

written By Matthew Joseph Nandirio   Reviewed by Dinu Sri Madusanka, PhD •  Updated: 05/31/22 •  5 min read

Gauge wire plays a crucial role in determining the overall performance and safety of the solar system. Without a proper wire size, you won’t have adequate voltage. On the other hand, it will also lead to excessive power loss. 

In this article, you will find all the details of the solar wire system. Therefore, you can also ensure the system runs smoothly and serves adequate voltage. 

Let’s get straight to the topic. 

What is the size gauge wire needed for a 100w solar panel?

For a 100-watt panel, the wire size should be four sq mm. if you can integrate the right size, you will be able to generate up to 20 amps of energy. 

Solar PV Panels can generate Direct Current. Hence, it is required to use Direct current wires to connect the inverter and charger. Hence, it will increase the overall efficiency and voltage capacity of the entire solar system. Even the wires should be UV-protected to work in outdoor conditions. 

Let us first take a look at the right size of gauge for different solar panels:

No. of solar panelsAmpsCorrect Wire Sizes
1 (100-375 watt)20 amps4 sq mm
3 (100-375 watt)30 amps6 sq. mm
6 (100-375 watt)50 amps10 sq. mm

Keeping no panel and watt range in mind, you can choose the ideal wire size. Moreover, if you use an undersized wire, it will likely result in excessive heat. Eventually, it can lead to fire damage. 

Like a water hose, an electrical wire also has a specific limitation in carrying voltage and power. If you integrate a small wire, then the solar system supplies less power to the battery grid. 

You will quickly get all the sizes in your local hardware store, or you can also order online. 

How do you determine the size of a gauge wire?

For copper wires, there is a specific gauge scale. It is American Wire Gauge. If you use a lower gauge number, it will have lower resistance power. 

Commercially, if you install solar panels of 50 watts, you have to use 10 AWG gauge wires. In addition, with the wiring system, 30 amps of current can flow, even if you are using a single panel. And if you can use combined panels, AWG will require a charge controller. 

The integrated charge controller to the battery bank would be the same compared to the PV array. If you set the PV array to operate at a higher voltage, a 12 to 24-volt battery bank would be adequate. In that case, a 1/0 wire size would be fine to run the system


In the table, you will find that the smallest wire is 10 AWG which can be rated at 30 amps. At the same time, it is required only 25 amps. Hence, it will ensure additional safety for wires and the entire PV solar system. 

Hence, it is important to consider the cable length and impact on losses in determining the cable and wire size. Using a long cable, you can reduce the performance of the power system. You can tolerate at least a 4% loss of power. 

To curb this issue, you can opt for high voltage like 24V. It also helps to decrease amps and wire losses. The drill is to design a system using safe wire and be aware of the connection between voltage, losses, lengths, and cost.

Why do you need to have the proper size of gauge wire?

Using a proper gauge wire is to transfer the current to the electrical appliances. Hence, it should have the least metrics of resistance. Therefore, the wire needs to be updated with the increasing number of appliances. 

Using a proper gauge wire is indispensable in using a PV solar panel. Let us find out the reasons:

  • Small wire can be meltdown with a large amount of current. Hence, it depends on the capacity of the cable. With a smaller diameter, you can ensure higher resistance. Therefore, the inadequate size of wire can lead to fire hazards. 
  • The proper size of the wire ensures the correct flow of electricity. Hence, a lack of power can isolate the ground and lead to current leakage. Eventually, a small amount of leakage can lead to blowing the amp.  
  • Fire damage can disrupt the entire wiring system. On the other hand, you have to comprise high voltage capacity. If the amplifier doesn’t receive proper voltage, its performance will be hampered significantly. 

In case you don’t know, voltage refers to electrical flow and ensures better performance of the electrical devices. 

Where can you buy a gauge wire for a 100w solar panel?

Buying a gauge wire is very convenient nowadays. And if you know the right size, it will be easier to find your perfect match.

For example: if you are looking for a four sq. meter wire, you will get it in local hardware shops. If you prefer shopping online, there is no better choice than Amazon. You can search for a four sq. meter wire.

For solar PV installation, I would recommend using Aluminium or copper wire. For residential and commercial use, copper wires are much better than Aluminium. Hence, it is a bit more expensive than the other. As copper has better conductivity, most engineers prefer them.

Go for top brands like LONGi Solar, Trina Solar, Hanwha Q-CELLS, and Sun Tech. Choose the one from the ‘Amazon Choice’ range. It will ensure the best deal.

To wrap up

I hope you understand the importance of having the right wire for the solar PV system. Choose the right gauge number from the table given here and ensure better performance and safety.

I would especially recommend not to compromise with the quality of the wires over price. The best price ranges from around $40 to $49. However, based on the size of the wire, the price will also change.

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