How to Wire Solar Panels

Connecting the components of a solar panel system requires the correct wire size to prevent a loss of energy, to thwart overheating, and to deter the possibility of starting a fire.  Wiring a do-it-yourself 12-volt solar system is possible with sufficient information found in an internet search. Following the correct order of steps and using a wire gauge and length diagram ensures a safe and efficient system. 

1. Gather Information:   

• Look up a wire sizing chart for connecting 12 Volt solar panels to a charge controller on the internet.


•  When the exact size of wire is not charted, always choose a larger gauge wire or use a longer than actual distance.


• Find information in an online search to determine the correct battery wiring diagram for the battery system.


• Choose parallel or series solar panel wiring.  In parallel wiring, the voltage remains the same and the amperage is calculated as the sum of all of the amps of all of the panels.  In series wiring, the amperage is the same as the amperage of just one panel, and the voltage equals the sum of the voltage of all panels.

2. Connect the charge controller:

• Connect the solar panels to the input terminal of the charge controller using the chart for reference to wire gauge and length.


• Use the same wire gauge to connect the charge controller to the batteries to ensure that the wires will not carry more current than the solar panel wires from the charge controller.

3. Connect the power inverter:

• The power inverter requires the largest gauge wires of the entire system due to the AC power produced by the power inverter drawing large amperage from the batteries.


• Do not exceed six-foot length in the connection to the batteries.


• Large cables get quite hot, insulation is recommended.

4. Connect the batteries:

• Batteries also require large gauge cable wires not unlike battery jump-start cables for vehicles.


• There are two types of solar wiring: parallel and series solar wiring.


• Connect all of the batteries in a parallel combination with positive terminals connected to the positive, and negative terminals connected to the negative.


• Series panel wiring is when the positive terminal of one panel is connected to the negative terminal of another panel.