Solar Panel Wiring Sizing Guide: Solar PV Cable Gauge (AWG) Calculation

The size of the solar panel wires are critical to the performance and safety of the solar pv system. Most home fires are caused by electrical faults that cause conductors to overheat. Selecting the correct wire gauge is critical to the safety and functionality of solar PV panels. Solar panel wire sizes are standardized using American Wire Gauge(AWG) and are made of copper wire. In general, the higher gauge off the wire&cable have higher the resistance. Meanwhile, high-spec wire&cable can only suit for lower currents.

An array of solar panels will capture solar energy and convert it into electricity. The flow of charge in the solar panel wires connecting the solar cell is limited by the thickness of the copper wire. The regular solar panel wire is 10 AWG. Use the water flowing in the hose analogy to understand solar panel wiring sizing. The larger the diameter of the hose, the easier it is for the water to flow. The shorter part of the hose flows more easily than the longer part of the hose.

Why choose 10 AWG (6mm) solar cable as the external connection wire of solar panel, firstly because 10awg solar cable is more soft and flexible, in addition, using this size cable can ensure safety and voltage drop. Therefore, different solar systems require different wire gauge sizes. Additionally, different parts of a solar system may require different wire sizes, such as common panels versus battery packs. This applies to both diameter and length. Solar power typically requires 12AWG pv wire, but cable size may vary based on specific factors such as resistance and flow.


What size cable should I use for 12V solar panel?

Generally speaking, most residential solar systems will work with 8 to 14 awg solar panel wire, depending on the exact wattage and amperage. To know which cable to use, you need to look at the amp. The amp will tell you the minimum AWG you should get based on a 2% voltage drop. So, before you understand the wires needed for a solar panel, you have to figure out how many amps the 12 V panel puts out. You need to do some basic math to figure out the amp.

Formula: Amps = Watt / Volt. We use this formula to find amperage, wattage or voltage. For example, if you know voltage and amps, you can find watts; if you know watts and voltage, you can find amps.

This formula is important because you must know the amps to determine the wire size for the solar panel. Therefore, in the remaining examples, we will refer to this formula to determine the exact power output and wire size of the 12 V panel.

Using the formula above, divide the wattage by the voltage. In this case, the voltage of the solar power system is 12 volts and the Vmp is 18. We still don't know watts, which is necessary to know amps. Wattage will depend on your specific needs and usage.

Say you have a 100 watt 12 V panel. Vmp is 18V. So divide 100W by 18V and you get about 5.5 amps. Assuming you only need 100 watts of power, you can use 14 AWG solar wire.

We came to this conclusion because a 14 AWG wire with a 2% voltage drop has a capacity of 15 amps.

What size wire do I need for a 200 watt solar panel?

Above, we learned how to calculate amps and wiring for a 12 V solar system. Now, let's apply the same formula and math to a 200W solar panel.

Solar PV panels are 12 V in most cases. Now that we know the wattage, we can better understand the amperage and wire size required for the system.

Divide 200W by 18Vmp as before. When you do that, you'll find that the amperage is exactly around 11. As before, you can use 14 AWG solar cable according to the 2% voltage drop chart.

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