Avasolar is reader-supported. When you buy via our links, we may earn a commission at no cost to you. Learn more

What Size Cable for 12V Solar Panel – Solar Panel Wire Size

Written by K. Miller / Fact checked by J. Fussell

what size cable for 12v solar panel

Before we delve into the question “what size cable for 12v solar panel?”, let’s first discuss what solar wires are. The sizes of solar wires are standardized utilizing the American Wire Gauge and are built using copper wires.

In general, wires constructed with higher numbers have more resistance; moreover, high gauge numbers can safely manage lower currents only. Hence, different solar panel systems require different wiring sizes like battery banks versus a standard solar panel. Please note that this applies to the length and diameter of solar panel wire size.

Typically, solar power calls for a 12 gauge AWG wire; however, the cable’s size might vary based on factors like flow and resistance.

What Cable Size Do I Need to Use for a 12-volt Solar Panel?

In general, most solar systems used for homes are compathible with wires between 8 and 14 gauges. Keep in mind that this depends on the precise amps and watts, which we will discuss in detail later.

Therefore, to point out which cable to pick, it’s essential to determine the amps. The amperage indicates the minimum AWG you have to get based on a 2 percent drop in volts. Check out the information and formula below:

How to Estimate What Solar Panel Wire Gauge You Require?


When determining the wiring size you need to get for your solar system; it’s critical to explore more about the following terms:

1. Maximum Current

Fundamentally, an electrical current flows between the electrical circuits. Did you notice that maximum current is usually represented with “I” when figuring out wiring size? Please be guided that the current indicates the flow rate, which is commonly expressed in amps.

2. Voltage Drop Index

This one determines the amount a short wire will minimize the voltage.

Substantially, a decline in the voltage allows a drop in the wire’s voltage and causes the power to be lost.

3. System Voltage

This term refers to the electric potential difference. In other words, it is the difference between the two circuit ends of the electrical charge.

What’s the Formula for Finding the Amps, Watt, or Voltage?

The formula: Amps = Watt/Volt

This formula is applicable for determining the voltage, wattage, or amperage, according to which of these variables is unknown or missing.

This is a valuable formula since it’s necessary to unveil the amps to determine the needed wiring size for your solar panel. Hence, we’ll refer back to this formula to determine the precise wiring size and power output of a 12-volt solar panel.

How Much Amperage Does a 12-volt Panel Put Out?


Referring to the formula mentioned above, you’ll need to divide the watts by the volts. In this example, the solar system has a Vmp of 18 and 12 volts. Here, the wattage is still unknown, which is necessary to get the amperage.

Your specific applications and requirements will figure out the watts.

Let’s do the math: 12-volt, 100W solar panel, and 18V Vmp

To solve, you’ll divide 100-watts by 18-volts = 5.5 amps. Presuming that you merely require 100W of power, you can utilize a 14 AWG solar wire.

We arrived at this conclusion because the capacity of a 14 AWG wire with a 2 percent drop in volts is 15 amps. Referring to our formula, the amp in our example is below the 14 AWG solar wire capacity.

Now to compute manually, replace the 100-watt with whatever wattages your solar panel requires. Afterward, compute the amperage. Most likely, you’ll require a cable between 10 and 14.

What is the Wiring Size Needed for a 200W Solar Panel?

Using the above formula, we learned how to compute the wiring and amperage for a 12-volt solar panel system. Now, we’ll use the same formula for a 200-watt solar panel.

Most solar PV panels are 12-volts. When you already know the watts, this enables you to understand better the wiring size and amperage required for the solar system.

Like what we did before, we’ll divide 200-watts by 18 Vmp; and we’ll get roughly 11. Same as before, we could utilize a 14 AWG cable as per the 2 percent drop in volts.

You might need to utilize a 24V solar panel instead. All you need is to adjust the math above and compute if this applies to you.

Can I Use 14 Gauge Wires for Solar Panels?

It is possible to utilize 14 gauge solar wires for your panels; however, this could solely handle 15-amperage at most. Please take in mind that many solar panels require higher amperage. Thus, we strongly suggest getting a 10 or 12 AWG wire to ensure satisfying outcomes on regular solar panels.

The examples mentioned above show that you can rely on 14 gauge cables to work excellently for solar panels in many scenarios. It’s worth noting that as long as the expected maximal amperage is below 15-amperage, a 14 gauge wire should work outstandingly for solar photovoltaic panels.

On the other hand, you can go for a 12 gauge wire if you’re unsure of exceeding 15 –amperage. Chiefly, 12 AWG wires are designed with an amperage capacity of 20 with a 2 percent drop in volts. It’s also worth mentioning that you’ll require a ten gauge wire for a maximum of 30-amperage.

Meanwhile, to determine how to select solar panel wire size for a DIY camper, you might want to check out this informative video:

How Can Using a Solar Panel Wire Size Calculator Help You?

If you don’t feel confident doing the math on your own when calculating the cables, another excellent method is using a solar wire size calculator.

This tool will make it much easier for you to compute the results; therefore, it’s unnecessary to refer to a voltage drop chart.

The Bottom Line

Choosing a suitable cable for your solar panel can be tricky. It requires detailed computations and a little insight into your energy costs. Nevertheless, once you fill out the necessary info to find out your maximum amps, you can effortlessly locate the appropriate cables you need.

Again, to determine what size cable for 12V solar panel, or would 30 amp wire size suit your needs, please refer to the following:

  • The maximum current, voltage drop index, and system voltage.
  • When computing manually, remember this formula: amps = watts divided by volts.
  • Use a solar panel wire size calculator if you don’t wish to do the math yourself.
5/5 - (3 votes)