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Solar Panels: Wire Gauge Between Battery & Charge Controller?

Find out which wire gauge is best between your battery and charge controller in your solar power system.

Solar Panels Jeremy Bezanger / Unsplash

Last Updated: October 4, 2021

Written by Brandon Jones

Wire Gauge for Battery to Charge Controller

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Below is a table showing which wire gauge you should get for connecting the battery and charge controller. The wire gauge is based on the amp rating of your charge controller.

For example, if you have a 30 amp charge controller, you'll want a 10 gauge wire connecting your battery and charge controller.

Wire Size - Battery to Controller
ControllerWire GaugeWire Length
20 amp 12 gauge < 10 ft (3 m)
20 amp 10 gauge 10–16ft (3–4.8 m)
30 amp 10 gauge < 16ft (4.8 m)
40 amp 8 gauge < 16ft (4.8 m)
60 amp 6 gauge < 10ft (3 m)
60 amp 4 gauge 10–16ft (3–4.8 m)

To help buy new solar equipment, check out the Recommended Solar Equipment section below.

Learn more about setting up a solar panel system in my Simple Solar Panel System - Setup & Equipment Guide.

Answers to Your Other Solar Panel System Questions

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Be sure to check out the articles in our solar panel series to help answer your other questions:

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Here's our list of recommended equipment for the most common solar power systems.

Solar Power System Cables


Batteries are used for storing the energy produced by your solar panels. The battery is wired between your power inverter and the charge controller. Never connect your power inverter and the charge controller directly without a battery between the two.

Charge Controllers

Charge controllers are used to regulate the voltage and current coming from the solar panels to prevent overcharging your battery.

Power Inverters

Power inverters are used for converting the battery's power (DC - direct current) into electricity used for powering your devices (AC - alternating current). Power inverters have an outlet on the device.

100W Solar Panel

Solar panels are made of many solar cells (photovoltaic cells), most often made from crystalline silicon. These cells take in energy from the sun's rays, converted through the semiconductor, creating an electric field that transfers voltage and current. Solar panels connect to the charge controller to regulate the voltage and current produced by the panel.


Fuses protect the wiring and devices from overcurrent. Fuses usually go on the closest point of the positive connection from your battery to the power inverter. You can also put fuses elsewhere in your system for protection, like an MC4 fuse for going between your solar panel and charge controller. You can find MC4 Fuses on Amazon (affiliate link).

Branch Connectors

Branch connectors are for merging the cables coming from multiple solar panels to your charge controller.