How to Wire a Solar Charge Controller for a DIY Camper Electrical System

This blog post will teach you how to wire a solar charge controller in your DIY camper electrical system. A solar charge controller regulates the power coming in from the solar array and converts it to a voltage and amperage that is safe to charge a battery bank with.

Parts & Tools Necessary to Wire a Solar Charge Controller

Turn off all Power in your System

Verify that you have no power flowing in your system. This means that you need to:

• Turn off your main battery disconnect switch
• Unhook from shore power
• Turn off all components (like your Inverter)
• Turn off your Solar Disconnect Switch

Using a multimeter to check for zero voltage at your positive and negative busbars and at the wires coming from the solar charge controller is a good idea at this point.

Wire the Solar Charge Controller Equipment Ground

The equipment ground screw needs a clear path back to the negative busbar in the Victron Lynx Distributor. This is important for if there is a catastrophic malfunction inside of the Lynx Distributor, there is a path back to the negative busbar so that power can flow in order to complete the circuit which would allow the fuse protecting the circuit to blow.

This is the solar charge controller equipment ground screw:

You need a wire with a 1/4″ wire lug on one side and a 5/16″ wire lug on the other side to make this connection

• Remove the Screw and washers using a phillips head screwdriver
• Place the 1/4″ wire lug against the heat sink
• Replace the washers and screw.
• Tighten to an appropriate torque.

Screw the Solar Charge Controller to the Backer Board

Since the ground screw is in an awkward place on the side of the charge controller and makes it difficult to access once there is a component to the left of the charge controller, it’s important to make that connection first. Now you can screw the charge controller to the backer board. 4x #14 x 3/4″ Pan Head Screws work great for this charge controller.

Attach the Equipment Ground Wire to the Negative Busbar

The next step is to attach the solar charge controller equipment ground wire to the negative busbar. This will go to the center stud on the negative busbar inside of the lynx Distributor.

• Remove the nut, washer, and lock washer with a 13mm socket.
• Place the 5/16″ wire lug onto the stud
• Replace nut, washer, and lock washer with a 13mm socket.
• Tighten to an appropriate torque

Wire the Solar Charge Controller Battery Negative Wire

Now I am going to wire the solar charge controller from the charge controller battery negative terminal to the negative busbar in the Victron Lynx Distributor.

To make this connection, I’ve made a wire with a 5/16″ wire lug on one side and a ferrule on the other side.

(Note: Ferrules are completely optional throughout this tutorial, but make for a very clean install. A stripped bare copper end of stranded wire is also an approved method.)

Next, I’m going to place the end with the ferrule in to the battery negative terminal of the solar charge controller and tighten the screw.

Now I’m going to connect the end with the 5/16″ wire lug to one of the studs in on the negative busbar inside of the Victron Lynx Distributor:

• Remove the nut, washer, and lock washer with a 13mm socket.
• Place the 5/16″ wire lug onto the stud
• Replace nut, washer, and lock washer with a 13mm socket.
• Tighten to an appropriate torque

Wire the Solar Charge Controller Battery Positive Wire

Now I am going to wire the solar charge controller from the charge controller battery positive terminal to the positive busbar in the Victron Lynx Distributor.

To make this connection, I’ve made a wire with a 5/16″ wire lug on one side and a ferrule on the other side.

I’m going to place the end with the ferrule into the battery positive terminal of the solar charge controller and tighten the screw.

Now I’m going to connect the end with the 5/16″ wire lug to one of the bottom ‘fuse holder’ studs and use a MEGA fuse to connect the wire lug to the positive

• Remove the nuts, washers, and lock washers on both of these studs with a 13mm socket.
• Place the MEGA Fuse in place

• Place the 5/16″ wire lug onto the bottom stud

• Replace nuts, washers, and lock washers on both fuse holder studs with a 13mm socket.
• Tighten to an appropriate torque

How to Wire a Charge Controller to a Solar Disconnect

Connecting the charge controller to the solar disconnect is simply a matter of connecting a positive and negative wire from the solar disconnect to the charge controller and tightening the terminals screws.

To wire the solar disconnect to the charge controller, I’m going to crimp on some ferrules onto the wires that are coming from the solar disconnect.

Wire the Solar Charge Controller Solar Negative Wire

Now I’m going connect the negative wire that goes from the solar disconnect to the charge controller:

• Insert the negative wire into the PV negative terminal on the charge controller.
• Tighten the screw down to an appropriate torque.

Wire the Solar Charge Controller Solar Positive Wire

Now I’m going connect the positive wire that goes from the solar disconnect to the charge controller:

• Insert the positive wire into the PV positive terminal on the charge controller.
• Tighten the screw down to an appropriate torque.

Use Cable Clamps for Wire Management

To keep the wires nice and tidy inside of the wire duct AND to keep the wires from wiggling out of the charge controller terminals, I’m going to put some wire clamps on the wires we just installed inside of the cable duct.

Double-check your Connections for Proper Polarity

Once all of the wires are connected, it’s time to go through and verify that positive wires are connected to positive wire terminals; and negative wires are connected to negative wire terminals. Systematically tracing each wire with your finger and pointing to the positive terminals is a great way to visualize that each wire is where it should go.

Turn on Battery Power to your System

Now I am going to turn on battery power to my system and if all goes well, I should be able to take a voltage reading with my multimeter and see somewhere in the 11-14.6V range for a 12V battery bank registering at the positive and negative battery terminals on my charge controller.

Turn on Solar Power to your System

Next, I can turn on the solar disconnect switch to connect my solar array to my charge controller. If all goes as planned, my solar array voltage should read at my positive and negative PV input terminals on my solar charge controller. Since I have 2x 100W solar panels wired in series, a reading of 44V is expected. Your solar array voltage may vary depending on it’s configuration.

Verify that your Solar Array is Charging the Batteries through your Charge Controller

Lastly, I am going to pull up the VictronConnect app on my phone and see that my batteries are indeed charging my battery bank at a rate of 15.6A

Installing a Solar Charge Controller – Finishing Up

The last steps for this project is to put the covers back on the Victron Lynx Distributor, replace the wire duct cover, and sit back and admire your handiwork on your newly installed solar charge controller.

Thanks for reading and I hope you found this blog post helpful and if you did… It’d be awesome if you would share it with somebody, or a group, who you think could use it.  Hit the like button, and leave any questions you’ve got in the comments section below.  Subscribe if you want to see more DIY camper building tutorials and I… will see you in the next project.