Solar Cable Sizing Calculator


These calculators help design efficient and safe solar power systems.

Solar cable sizing is a critical aspect of designing reliable and efficient solar power systems. It involves selecting the appropriate wire gauge to minimize power loss. You need to take into account factors such as distance, current, and voltage to ensure efficient electricity transmission from solar panels to charge controllers and batteries. In this blog, we’ll learn about solar cable sizing calculators that simplify these calculations.

Solar Cable Sizing Calculator

Photovoltaic cables serve to link the photovoltaic panels to the inverter, tailored to endure extreme weather and UV exposure. Their construction ensures resilience to temperature variations while offering excellent electrical conductivity. Now, let’s get a brief on solar cable sizing calculator and then find out how to size a cable for a solar system.

To determine the appropriate cable size for your solar panel system, familiarize yourself with the system’s electrical specifications. This involves understanding the working voltage of your solar system and any connected battery banks, considering the working power of the solar array, as well as assessing the cable’s operating temperature in either Celsius or Fahrenheit.

It’s essential to recognize that the cable’s working temperature significantly impacts its resistance, potentially leading to voltage drops and limiting the electrical current the wire can handle. Factors like wire length and diameter also influence resistive loss. Additionally, determining the desired percentage of resistive loss in the cable is crucial.

Once these parameters are established, you can calculate the suitability of your planned cable length in feet (ft) using the gathered information. You can also use American Wire Gauge (AWG) to help pick the correct solar cable size. The lower value of AWG means larger wire, better current flow, and less voltage drop. Based on your requirements and relevant parameters, you can utilize various DC and AC solar cable sizing calculators to determine the suitable wire size for your solar power system.

Commercial panels over 50 watts use 10 gauge wires, allowing up to 30 amps per solar panel. If multiple panels are connected in parallel, you will need a 3 to 8 AWG combiner wire for safe and efficient power transfer to a controller.

How to Size a Cable For a Solar System

Solar Cable Sizing Calculator
By Getty Images from Unsplash+

After learning about solar wire size calculator, here is a guide on how to calculate solar wire size:

  • Determine the voltage drop: Voltage drop refers to the loss of voltage during the cable’s current flow. It is recommended to size the wire to achieve a 2 or 3% drop at the typical load.
  • Calculate the amperage: Amperage represents the current flowing through the cable, which can be calculated by dividing the solar panel’s wattage by the voltage to obtain the amps.
  • Choose the suitable wire size: Selecting the right wire size depends on both the amperage and voltage drop. Referencing a wire sizing chart helps determine the maximum one-way distance in feet for various gauge two-conductor copper wires, ensuring a 2% voltage drop.
  • Consider the cable length: Cable length significantly impacts voltage drop. By utilizing the known resistance of different wire gauges, it’s possible to compute the maximum length for each wire gauge size.
  • Select the appropriate cable type: Opt for solar cables specifically engineered to endure the rigorous outdoor conditions commonly encountered in solar installations. These cables are designed to be flame retardant, fire-resistant, and capable of withstanding extreme weather conditions, UV exposure, and varying temperatures.
  • Consult a licensed electrician or solar installer: Seeking guidance from a licensed electrician or solar installer is crucial to ensuring the proper design and installation of your solar power system.

You can also consider this formula to find the Voltage Drop Index and thus estimate the cable size:

VDI (Voltage Drop Index) = (Total amperage ×— length of the cable in one way)/( Voltage ×— voltage drop%)

Now, according to this result, you can use this VDI chart, 


You can find the apt cable size for your solar panel system by using this table. For instance, for a 24V panel, if you have a 10 Amp load, and need to cover a distance of 100 feet with a 2% loss, you calculate a VDI value of 20.83. So, based on this table data, you will need a 4 AWG cable.

Cross-Reference: Selecting wire size based on voltage drop for solar systems

Can I Use a 2.5 mm Cable for Solar Panels?

Yes, you can use a 2.5 mm cable for solar panels. In fact, it is one of the most popular sizes for DC cable. Now, let’s see if you can use a 1.5mm cable for solar or not.

Can I Use a 1.5 mm Cable for Solar?

Yes, you can use a 1.5mm solar cable for solar power systems. There are several 1.5mm solar cables available for purchase, and they are suitable for connecting solar panels and solar generators. After this, let’s find out what size cable for a 10kW solar system is most suitable.

For a better understanding of solar wire size calculator, you can take a look at our blog Solar Cable Size Selection Guide For PV Plants

What Size Cable for a 10kW Solar System?

After learning about solar panel cable size calculator, let’s find out what size cable is suitable for a 10kW solar system. Well, the suitability of cable size relies on various factors such as the gap between the solar panels and the charge controller or battery bank, the system’s voltage, and the maximum current flowing through the cable.

What Size Cable for a 5kW Solar System?

Solar cables wiring: Solar Cable Sizing Calculator

To connect a 5kW solar panel to the DC distribution box (DB), you can use a 4 sq. mm DC cable. For the connection from the DB box to the inverter, a 6 sq. mm DC wire is recommended. 

Additionally, check out the 5 Key Differences Between Solar Cable and Normal Cable

What Size Cable for a 20kW Solar System?

For a 20kW 12V renewable energy system with less than 5% voltage loss, you will require a two-core cable with at least 0.5 sq. mm cross-section.

In summary, the solar cable sizing calculator is a vital resource for both professionals and enthusiasts in the solar energy industry. By providing accurate calculations, you can ensure efficient installation and operation of solar power systems, thus fostering sustainable energy practices.

Recommended: Solar Panel Charging Time Calculator

One response to “Solar Cable Sizing Calculator”


Leave a Reply

Your email address will not be published. Required fields are marked *