How Much Solar Power Do You Need to Run a Refrigerator?


It takes between 300 to 400 watts of solar energy to run a full-size refrigerator. The exact amount depends primarily on the refrigerator’s consumption, your location, and the solar panels.

In this article, we lay out how you can use solar panels to run a refrigerator. We explain just how many solar panels you will need and which ones are the best.

How Many Solar Panels Does It Take to Run a Residential Refrigerator?

One will need at least two solar panels to run your home refrigerator. The refrigerator consumption, the geographic location, and the type of solar panel will determine whether to use two or more.

How do those factors determine the number of solar panels you need? Let’s look at each in detail to find out.


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Refrigerator consumption

Most domestic appliances like TVs, laptops, and radios run on a continuous current. That means the current flows continuously at the same rate while the appliance is in use. A TV rated at 250 watts will use 250 watts while you’re watching.

Appliances like refrigerators, air conditioners, and geysers on the other hand run on an intermittent current. That means the current does not flow at the same rate while the appliance is in use. The current can be high when the appliance is working or low when it is idling.

What do we mean by “working” and “idling” and why is it important? A refrigerator has a starting current, a working current, and an idling current.

  1. The starting current is a high current the refrigerator draws to start the compressor motor it uses to cool the air inside it. This can be up to 700 watts.
  2. The working current is the current used when the motor is running and your refrigerator is actively cooling the air inside.
  3. The idling current is the resting current when the refrigerator is on but not working because the temperature inside is already cool. If your refrigerator worked continuously, it would freeze everything! That’s why it has a thermostat to regulate its temperature.

How to work out the consumption of your refrigerator

Working out the consumption of your TV is simple. You just multiply how many watts it uses by the number of hours you use it for. This is what it looks like in practice.

250 watts X 5 hours = 1,250 watts or 1,25 kWh

Working out the consumption of your refrigerator is a little more complicated because it does not have a continuous current as your TV has. If we used the same formula for your refrigerator as we did for your TV you would overshoot the consumption. What we want is real consumption, not the rated consumption. So how do we work out real consumption?

We work out the real consumption by taking into account the duty cycle of your refrigerator. The duty cycle is the time, expressed as a percentage, your refrigerator spends working. This is the time when the motor is running and consumption is highest. (Source)

A refrigerator with a duty cycle of 0.7 has a motor that runs 70% of the time. Once you know the duty cycle of your refrigerator you can use that to calculate the real consumption. All you do is multiply the rated consumption by the hours of use and the duty cycle. Here is what that looks like in practice.

150 watts X 24 hours X 0.7 duty cycle = 2,520 watts or 2,5 kWh

Some refrigerators give the current rating in amps. To convert this to amps all you do is multiply the voltage by the amps. In the U.S refrigerator voltage is 110 volts. The watt rating of your refrigerator would therefore be:

110 volts X 1.36 amps = 150 watts

Once you have worked out the consumption of your refrigerator the next step is to find out how much sunlight you receive in your location.

Peak sun hours

Depending on where you live you might receive more or fewer hours of peak sunlight. Your peak sun hours will determine how much solar energy your solar panels will produce. The more sun hours you receive, the more light there is for your solar panels to convert to electricity.

Some states in the U.S are sunnier than others. If you live in the sunnier states, you typically require fewer solar panels compared to someone who lives in a cooler state. You can check how much sun you receive at your address with Google’s Project Sunroof. (Source)

Once you know your consumption and how many peak sun hours you receive you can then work out how many solar panels you need.

Your solar panels

We’ve worked out that your refrigerator needs 2,5 kWh. Let’s assume you receive five peak sun hours at your address. How much solar energy would you need to produce 2,5 kWh in five hours? You would need to work out how much energy per hour by dividing total energy by time.

2,5 kWh (2520 watts) / 5 hours = 0.5 kWh or 504 watts

You would need to produce 504 watts. Now you know how much energy you need so working out how many solar panels is easy. How many solar panels will produce 504 watts? You could just use 2 solar panels that produce 250 watts each. A better way would be to slightly oversize your system by getting a 300-watt and 250-watt solar panel to give you 550 watts.

Can You Run a Refrigerator on A 100-Watt Solar Panel?

You can run a refrigerator on a 100-watt solar panel. This would, however, be insufficient as the solar panel would not supply you with enough energy to run the fridge for the entire time it is on.

Will a 200w Solar Panel Run a Fridge?

A 200w solar panel can run a fridge but only for a short time. A 200w solar panel will give you between 800 to 1000 watts of power in a day. Most fridges need about 2000 to 2500 watts of power to run throughout the day.

What Size Solar Panel Do I Need for A Refrigerator?

You need at least two solar panels rated at 250 watts to supply enough power to run your refrigerator. This would keep the refrigerator running for the whole time it’s in use.

sherifjallad

I am a very well-experienced techie civil engineer who’s extensively interested in solar panel technology and even more captivated by the potential of solar panels in supporting individual residential units.

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