What Is Solar Panel Cable Size?

What Is Solar Panel Cable Size?

To understand what “size” means, think of solar panel cable size in terms of a water hose. The more water you need for an application, the larger the diameter of the hose that’s required. Additionally, shorter hoses deliver greater water flow than longer hoses of the same diameter. It’s the same with solar panel cable.

If your solar wire size isn’t large enough (wire cross-sectional area or gauge), or if you use a longer solar power cable than you require, then the current will meet with higher resistance than you expected, causing fewer power Watts to move from your solar panels to the grid or battery bank. So, you really can’t say one size fits all or that one size solar PV cable is better than the other. For instance, depending on what your application is, a solar cable 6mm specification might be more appropriate than a solar cable 4mm size. In another application, the reverse might also be true – 4mm cable may be the better choice compared to 6mm.

Calculating the right solar cable size involves doing some math and then using a standard American Wire Gauge (AWG) chart. The AWS scale works in reverse, with solar wire type with lower AWG numbers representing higher wire cross-sectional area, which corresponds to less resistance and lesser voltage drops.

Here’s how to calculate the solar cable size you need:

First, you’ll be calculating the Voltage Drop Index (VDI). You do this by using the voltage drop percent (or VD%), the length of the wire (length in feet) and the amperage (current) of the application. VDI is calculated by using the formula (Amperage x feet) / (VD% x voltage)

Next, determine your solar cable size by using the VDI calculated above, and matching it with the AWG chart:

Depending on your application, elements such as maximum voltage drop and amperage may differ for each section of your photovoltaic system. For each segment of your application, calculate the solar wire requirement based on the appropriate cable length, amperage, and voltage loss factor. The sizes of your solar cable may be different for each part of your application.

You may need a 10 AWG solar cable to connect the charge controller or inverter to your PV panels

You may require a different size of pv cable to connect batteries to charge controllers

And, you might need a different size of solar PV cable to link your inverter to the grid

Ultimately, therefore, you might use a solar cable 4mm for one segment of your solar electrical system, a solar cable 6mm, and twin solar cable for another part of the system, with an MC4 solar cable extension to link to the equipment being powered by solar electricity.