In this tutorial, I’ll show you step by step how to solar power a 12V fridge.
In fact, these are the exact steps I used to create my own solar powered mini fridge.
The good news is solar powering a fridge isn’t too hard. I’ll cover all the parts you need, as well as some tips on which solar panel kit and battery to get.
Let’s get started.
Video: How to Solar Power a 12V Fridge
Here’s a 40-second video overview of this tutorial. Check it out below and consider subscribing to my YouTube channel if you like DIY solar videos like this!
Parts & Tools
- 100W 12V solar panel kit
- 12V fridge with its included 12V power cord
- 12V 100Ah LiFePO4 battery — this is the battery I used, but feel free to use a different one
- 30A ANL fuse set — a 30 amp fuse is the right size for the charge controller in the kit linked above
- Fuse cable
- 12V socket — for connecting the fridge to the battery (I’m assuming your fridge’s 12V power cord has a 12V car plug)
- Wrench or ratchet — for tightening bolts
Note: Feel free to copy this parts list as is or use the tips in the sizing sections below to pick your own.
Step 1: Understand the Wiring Diagram
Here’s the wiring diagram I’ll be using to solar power my fridge:
And here are the main things to understand about it:
- Power the fridge off the 12V battery. You can’t power a 12V fridge directly with a solar panel. Instead, you need to store the solar energy in a 12V battery and power the fridge off of that.
- Connect the battery and solar panel to a solar charge controller. You’ll damage your battery if you connect your solar panel directly to it. The battery needs to be connected to the solar panel via a solar charge controller, which regulates the voltage and current output by your solar panels to safely charge the battery.
- Protect your setup with a fuse between each connection. Safety best practices are to place a fuse on the positive wires between the battery and charge controller, and between the battery and the fridge. If you use multiple solar panels, you may also need to place inline solar fuses between the solar panels and charge controller. Refer to this video for guidance on whether or not you need to place fuses there.
- Make sure all your equipment is rated for 12 volts. If you follow this wiring diagram, make sure you’re using a 12V fridge, 12V battery, and 12V solar panel. Your charge controller should also be compatible with 12V systems.
- If you’re using a PWM charge controller with multiple solar panels, wire the solar panels in parallel. Wiring solar panels in parallel sums their currents while keeping the voltage the same. Parallel wiring is what I recommend when using a PWM charge controller. If you’re using an MPPT charge controller, I’d recommend wiring your solar panels in series.
With all that out of the way, it’s time to start building.
Step 2: Connect the Charge Controller & 12V Socket to the Battery
Connect the positive battery cable (included in the solar panel kit) and fuse cable to the ANL fuse. Use a wrench or ratchet to tighten the bolts.
Now we’re ready to connect the charge controller and 12V socket to the battery.
Locate the battery terminals on the charge controller. They’ll usually be labeled with a battery icon or the word “BAT” or “BATT.”
Note: I’m using a different charge controller than the one included in the 100W kit linked above, but the steps are the same. Apologies for any confusion!
Connect the positive battery cable to the charge controller’s positive battery terminal, and the negative battery cable to the charge controller’s negative battery terminal. For most charge controllers, you need a screwdriver to do this. Open the correct charge controller terminal with your screwdriver, insert the stripped end of your battery cable, then screw the terminal shut.
At this point, your battery cables are properly fused and your charge controller is now ready to be connected to your battery. We’ll connect both the charge controller and 12V socket to the battery at the same time.
Connect the positive battery cable and positive 12V socket wire to the positive battery terminal. Once again, use a ratchet or wrench to tighten the bolt.
Connect the negative battery cable and negative 12V socket wire to the negative battery terminal. There may be a small spark when you touch the battery cable to the terminal. This is normal.
Your charge controller is now connected to your battery, so it should power on.
Confirm that your charge controller is now powered on. If it has a screen, the screen will turn on and start displaying system specs, such as battery voltage. If it doesn’t have a screen, it should have LED indicators that light up or start flashing.
Select your battery type on your charge controller following the instructions in the controller’s manual. I’m using a lithium iron phosphate (LiFePO4) battery, so I selected that option on my controller.
Your charge controller and battery are now properly connected! Here’s what my setup looked like at this point:
Step 3: Connect the Solar Panel to the Charge Controller
Locate the solar terminals on your charge controller. They’ll usually be labeled with a solar panel icon or the word “PV.” (PV stands for photovoltaic module, which is another term for a solar panel.)
Cover your solar panel(s) with a towel, or flip them face down to reduce the risk of electrical shock.
If you’re using multiple solar panels, wire your solar panels in parallel using branch connectors. For this tutorial, I’m using only the one 100W panel included in the kit. But here’s what it’d look like if you were to wire 2 panels in parallel.
Connect the positive and negative solar panel cables to the solar adapter cables (included in the kit). Once you do, make sure the exposed wire ends don’t touch.
Connect the positive solar cable to the positive solar terminal on the charge controller. Connect the negative solar cable to the negative solar terminal on the charge controller. Once again, use your screwdriver to do this.
Uncover or flip over the solar panel and place it outside in direct sunlight. My deck had a lot of shade because of nearby trees, but I found a spot that was mostly sunny.
Confirm that the solar panel is now charging the battery. If your charge controller has a screen, it may indicate charging is happening with a battery charging icon. If not, navigate to the PV current screen and you should see a positive number. If your charge controller doesn’t have a screen, it should somehow indicate charging with its LED lights.
I went to the PV current screen to confirm. It showed a current of 0.6 amps. That means my solar panel is charging my battery at a rate of 0.6 amps. (The current is low for a 100 watt solar panel due to the shading on my panel.)
All we have left to do now is connect the fridge.
Step 4: Connect the 12V Fridge to the Battery
Connect the fridge’s 12V power cord. In case you’re wondering, I’m using the BougeRV 12V 30 Quart Portable Fridge.
Plug the fridge into the 12V socket that you connected to the battery.
Confirm that your fridge is now powered on. This means your fridge is now successfully connected to your battery. At this point, you can adjust the fridge’s temperature and other settings to your liking.
That’s it! You now you have a solar powered 12V fridge. The solar panel safely charges the battery via the charge controller. And the 12V fridge runs directly off the 12V battery.
Here’s a picture of my final setup:
How Many Solar Panels Do I Need to Run a 12V Fridge?
Most people will need 100 to 200 watts of solar panels to run a 12V mini fridge. That should power your fridge long enough to last most short camping, RVing, and boating trips.
To build a solar array of this size, it’d be easiest to buy either a 100W solar panel kit or a 200W solar panel kit. If you already have a 100W solar panel kit, then you can easily add a second panel by picking up an identical solar panel and wiring it in parallel.
How did I come to this recommendation? Through a couple different tests.
First, I measured my 12V fridge’s power consumption and learned that it uses around 350 watt hours per day. Next, I also tested how much energy a 100 watt solar panel can produce, and determined that it typically ranges from 300-500 watt hours on average per day. (I used an MPPT charge controller in that test. With a PWM charge controller you can expect a little less.)
So, if I were to mount my 100 watt solar panel in a sunny spot, then, on average, it would generate around enough energy to offset my fridge’s power consumption. That should make my battery last as long as I need for most of my camping and RVing trips.
However, my 12V fridge is on the smaller end, and many other models use more power than mine does. And if you need your fridge to run for longer stretches of time, then your battery could get drained after a stretch of cloudy days. So some people will need 200 watts of solar to power a 12V fridge. For full-size 12V RV fridges, you’ll probably need even more.
Remember: These suggestions are assuming the fridge is the only thing you’re powering off the battery.
What Size Battery Do I Need to Run a 12V Fridge?
When I tested how long a 100Ah LiFePO4 battery would run a 12V fridge, it lasted for a whopping 102.5 hours.
Based on that test, I think a battery bank with 100-200 amp hours of usable capacity is a good size for running most small 12V fridges. (This is assuming you’re using your battery bank to power your fridge only.)
That size should give most people 3-4 days of runtime off the battery bank alone. Combined with a properly sized solar array, it should be enough to run your 12V fridge for 24 hours a day.
If using lead acid batteries, get two to four 100Ah 12V lead acid batteries or one to two 200Ah 12V lead acid batteries. A lead acid battery bank needs to have double the amp hours because lead acid batteries have only 50% usable capacity.
For this project, I recommend connecting multiple batteries together by wiring them in parallel. This keeps your battery bank voltage at 12 volts while expanding its amp hour capacity.
Note: There are a lot of variables at play here which may affect the right battery size for your setup. 12V fridges vary greatly in how much power they use based on their size, insulation, and whether or not they have a freezer compartment. Factors like ambient temperature and how often you open the fridge also affect power usage. If you find your battery bank dying often, that’s a good sign you should expand it.
What Size Charge Controller Do I Need?
30A charge controllers are usually rated to handle up to 400 watts of solar power when installed in 12V systems, so you can expand your solar array later on if you find one 100W panel isn’t enough. If your solar array is larger than 400 watts or you’d rather connect your solar panels in series, I’d recommend an MPPT charge controller.