In this post I wanted to do an experiment to see how many batteries and solar panels I would need to power my garage deep freezer using my DIY Solar Generator. I am not only trying to see how long it will run it. I am also trying to figure out what it would take at a minimum to run the freezer on a daily basis.

Keep reading below or checkout my YouTube video below.

I have this upright 20 cubic foot deep freezer in my garage. If the power was to go out for an extended period of time, it would be very costly if I lost all that food in there.

If I did nothing, deep freezers typically keep things frozen for 2 or 3 days or possibly more depending on how full the freezer is, how often you open it and the temperature in the area around your freezer.

If your freezer is full and you don’t open it, it will definitely stay frozen longer. I could have just as easily done this same experiment with my garage refrigerator.

This experiment could apply to the refrigerator also.

Ok, so here is the setup. For the experiment, I have this Frigidaire 20 cubic feet stand up deep freezer

Here is the energy guide for the freezer.

I will use this DIY Solar Generator I built a couple of years ago to power the freezer.

The solar generator includes this 30amp MPPT solar charge controller, which I did a video on over a year ago

I’m going to start with just one 100ah 12v power queen battery and one BougeRV 200w rigid solar panel

I chose the power queen battery because I have two identical batteries. I’m hoping I don’t need more than 2 batteries.

You are supposed to use identical batteries when you hook them together in either series or parallel. But if the experiment goes over two batteries, I should be ok just for this experiment without damaging anything.

I’m going to put the solar panels up against this fireplace facing slightly southeast.

At the time I am filming this, it is January and the temperature outside is in the mid to upper 20’s Fahrenheit.

In Dec and Jan, you won’t get very much sun as you would in the summer, but you do get a little more output from the panels because the temperature is so cold.

The garage is heated a little bit with an oil heater and the temperature in the garage is about ?? degrees Fahrenheit.

I have already charged the battery to 100% and we are ready to get started with the experiment.

Day one,

I’m using a single 200watt BougeRV rigid solar panel for the first test.

We have a decent amount of sun at about 8:30am.

The single panel kept the battery topped off until about 1pm when the shade started hitting the solar panel and the battery started going down from 100%

At 6pm we are now running fully off the battery the the state of charge was 65%

At 10pm, the battery was down to 73%

I’m thinking the battery should hold through the night.

Day Two

The battery is all the way down to 35 percent in the morning.

At the end of the day it was clear the battery would not make it through the night.

Ok, now I am adding an additional solar panel in series.

Day 3

I started off with a single battery charged to 35 percent and two solar panels.

Two panels were enough for the two panels to fully charge the battery.

I’m now just going to let it run day after day until something changes.

Day 4

Day 4 is very cloudy and the panels will not fully charge the battery.

I’ve decided to do is to add another battery and another panel

The reason I’m adding another panel is to have enough solar power in a single day to charge both batteries.

The new panel on the right is actually a NewPowa brand solar panel. But the specs are almost identical. So its fine to do that.

Now I’ve actually run out of panels to add. I do have this one that shattered on me. But I don’t want to use that one.

So there has been a development.

I was checking the voltage limit of this mppt solar charge controller to make sure it can handle the 3 panels in series,

and I noticed that this charge controller will only produce 400 watts of power when using a 12v battery system like I am using here.

So I’ve had to switch that one out for this HQST 40amp MPPT charge controller. It will handle up to 600 watts of power which matches what our solar panels can output.

I’m glad I noticed that.

To kind of restart this experiment using the 3 panels and two batteries, I’ve had to charge both batteries to full

Then set my battery monitor to 100% and change the capacity to 200ah, since I am using two 100ah batteries now

I’ve plugged the freezer back into the inverter.

Its about 5 pm on day 4 and we will see where we stand in the morning

Day 5 – 9

Day 5-6 was good sun and everything charged up nicely. But day 7 – 8 was rainy and cloudy.

I stopped the experiment on day 9 since we have learned enough.

The first thing this experiment taught us is that powering something like a freezer or refrigerator with only solar takes more solar panel and battery capacity than most people realize

In a world of perfect sunny conditions every day, it would be much easier.

The experiment also taught us that when you increase the battery capacity, you also need to increase the solar panel capacity because you have to be able to charge the extra battery capacity back to full.

We learned that a single 100ah 12v battery and 200 watts of solar could definitely help you get through most power outages.

But you definitely could not rely on that for any long term means of powering the freezer or refrigerator.

The single 200 watt panel was just not enough to charge the battery up to 100% in a single day

So I added that 2nd 200w panel bringing us up to 400 watts of solar

This allowed the solar to charge that single battery to full in a day.

And since we know the battery can hold up until the next morning sun arrives, this setup could power the freezer indefinitely given you had enough sun each day.

So I would say that a total of 400 watts of solar and a single 100ah 12v battery would be the absolute minimum of what it would take to power that freezer full time

And as I said, that is assuming you have good sun every day.

However, getting enough sun every day is just not realistic for most people.

Where I live we sometimes see several days in a row of heavy clouds.

So on day 4, I added a third panel and 2nd battery for a total of 600 watts of solar and 200ah of 12v batteries.

That was enough to make it through several days in a row which included partly cloudy days one very cloudy day. It almost made it through two very cloudy days in a row, but it was just not enough to make it through the night.

I ended the experiment there since my charge controller was at its maximum input and I ran out of compatible solar panels.

Also, we learned that at this point, you just need to keep adding solar panels and batteries until you can make it through enough consecutive cloudy days in a row that for area you live in.

As you continue to add more capacity, the way to connect your panel and batteries together changes. Be sure to consult your equipment’s owners manuals.

For example, these batteries can only connect 4 in parallel. But you can go up to what they call 4s4p configuration which is a topic for another video.

If would say that if I had 800 watts of solar and 300ah of 12v battery capacity, I believe I would feel somewhat comfortable with running the freezer full time.

But when you have several days in a row of cloudy days, all bets are off.

You just need some other way to power the freezer or refrigerator when mother nature strings together several consecutive cloudy days like that.

Before I close, here are just a few other noteworthy items about this experiment.

The temperature in the garage being in the upper 50’s almost certainly helped reduce the power consumption to some point.

My freezer is fairly new and efficient. Your freezer or refrigerator may be different and you could experience different results.

Those chest freezers I believe are more efficient than the upright one I have. When I open the door, the cold just comes pouring out.

I also never really tried to maximize the solar panel positions or angles. I could have gotten a little more out of the panels if I had done that.

But not enough to significantly affect the experiment.

The total reading on the watt meter ended up being 5.9 kwhs. But since I powered the freezer off of grid power a couple of times. This reading is not really that useful.

Well, I hope you have enjoyed this experiment as much as I did.

Thanks for reading.

Affiliate Links

HQST Solar Charge Controller https://amzn.to/3WW0aMi

PowerQueen 100ah 12v LiFePO4 Battery https://amzn.to/3WSOnOI

Similar BougeRV Solar Panel (the ones I have are no longer available) https://amzn.to/40PlO64

Battery Monitor https://amzn.to/3QbmRbu Watt Meter https://amzn.to/4aZwrYv