How Many Solar Panels Do I Need To Power a Refrigerator?

On average, you would need between three and four solar panels to run a refrigerator. The number of solar panels needed can vary based on the power requirement of your fridge, the construction of your panels, as well as the size of your inverter and battery storage system. On top of this, further variables will affect your solar panel output efficiency.

In this article, we will discuss all these factors and how they affect your sustainable energy setup.

How To Calculate How Many Solar Panels Are Needed To Power A Refrigerator

You can easily calculate how many solar panels you need to power your refrigerator with our simple formulas below. However, you will also need to consider the additional solar energy required to charge your storage battery so you can power a refrigerator at night.

Calculating refrigerator power consumption

First, you need to calculate the energy consumption of your fridge in a day. Modern fridges use between 100 W and 400 W per hour.

The formula is:

(Power usage) X (hours of operation) = (Total power consumption)

The fridge compressor only runs when the internal ambient temperature rises. On average, a fridge runs at capacity only about 8 hours a day.

Example:

• Let’s take a conservative estimate and say that your fridge runs 12 hours per day and has an average electricity consumption of 200 W per hour.
• Your formula will look like this: (200 W per hour) x (12 hours) = 2,400 W daily energy required

Calculating the size of your storage battery

Now, you need to calculate the size of the battery that can store enough charge to power the fridge during the night.

The formula is:

(Daily Energy required) / (Battery efficiency rating) = (Battery capacity required)

The efficiency is how much of the battery’s stored solar energy can be transferred to an appliance. No battery is 100% efficient. There will always be energy lost when energy is moved from one state to another.

Example:

• Let’s use a lithium-ion battery with an efficiency rating of 95%.
• Your formula would look like this: 2,400 W/ 0.95 (95%) = 2,526 W

In this case, you would want your a battery with a storage capacity of 2,500 W.

Determining the number of solar panels required

Working out the number of panels required to power your fridge is another simple formula:

(Power required) / (output per panel x sunlight hours) = Total solar panels needed

Determining how much energy you receive from daily sunlight is tricky as it varies throughout the UK. On average, we get up to 5 hours of sunlight per day.

Of those 5 hours, only 2.5 are considered peak sun hours. Peak sunlight hours give solar panels access to optimal daily energy production.

Example:

• For this example, we will use a 300 W solar panel, which is the average output for panels. We’ll also assume your panels will only receive 2.5 hours of sun per day.
• Your formula would look like this: 2,400 W / (300 W solar panel x 2.5 hours) = 3.2 panels

This means to match your 200 W refrigerator’s power consumption, you will need four solar panels to run it. This will also be enough to charge the storage battery for nighttime operation.

Additional components

In your solar setup, you will need two additional components: an inverter and a charge controller. These are essential but will increase the percentage of energy lost in the system. Fortunately, they do not have a huge impact on the system’s efficiency.

• Inverter: The inverter is needed to convert the DC power from the solar panels to AC power that your fridge can use. This can lower your solar setup’s efficiency by up to 2%.
• Charge controller: This device manages the flow of energy between your solar panels and your storage battery. It can lower power efficiency by up to 5%

What Factors Influence Solar Panel Output Efficiency?

The amount of energy that solar cells convert to usable power is referred to as the output efficiency. Factors that influence this include the construction of solar panels, the way the panels are installed, and how they are oriented towards the sun, along with many geographic variables.

Let’s take a closer look at these factors. 

Brand and model

Being outside in the elements means that solar panels experience a lot of weathering. The more degraded a solar panel becomes, the lower its output efficiency. While cost is an important factor for any home or business owner, installing quality brands or models will result in better output and overall energy efficiency.

Quality panels resist weathering for longer. The materials that make up the internal conductive cells in more high-end panels are also often twice as efficient as cheaper models.

Type of solar panel

The type of solar panels you install can also impact their efficiency.

For example, top-quality monocrystalline solar panels are made of very pure silicone and convert 20% of sunlight to solar power. On the other hand, cheaper thin film solar panels only manage a 10% conversion rate.

Shading

Depending on your surroundings and the location of your solar installation, your panels may be in the shade at different points during the day as the sun moves.

Shading affects solar panels by reducing the amount of sunlight hours they receive. Surrounding buildings, trees and other obstructions adversely affect solar power output.

Since even the most efficient solar panels only convert 20% of the sunlight that hits them into energy, just a small amount of shade on your panels will have an effect.

Maintenance

As with shade, any dirt or debris that falls on solar panels will adversely affect the efficiency of their power delivery. To get the best from your solar power setup, arrange maintenance or cleaning visits annually.

Location

The further away you are from the equator, the less direct sunlight hits your panels, reducing their efficiency.

Additionally, if you live in an area with a lot of rain or cloud cover, your panels will experience fewer peak sunlight hours. While solar panels are worth it in the UK, you may need to add a few more panels to your setup to improve their overall power output.

System design

The panels, inverter and battery used all determine your solar system output. Higher-end equipment will offer higher energy efficiencies and outputs.

An experienced solar installer, like Eco Happy, will be able to advise you on the best design for your solar array and storage solutions.

For example, a lithium-ion battery has an energy efficiency of 95%. However, a lead-acid storage battery only has an energy efficiency of between 80% and 90%.

Age and weathering

It is estimated that solar panels lose about 0.5% of their efficiency per year. This means that in 25 years, your panels might be half as effective as they originally were.

However, this degradation could be closer to 0.1% with a well-maintained system. This means that you will have reliable solar power for at least a decade after installation.

Installation quality

Every component of a solar power array works in unison to deliver a steady flow of current to power your refrigerator. However, there are many potential points of failure or inefficiencies.

This is why getting an experienced, professional installer to set up your solar power system is so important. It ensures properly sized and specced components that will increase total output efficiency.

Panel orientation and panel tilt

The angle at which solar panels are tilted affects how many peak sun hours it receives.

The panel should also have the correct orientation, depending on which hemisphere you are located in. Since the UK is in the northern hemisphere, the ideal orientation would be in the southern direction. This will expose the panel to the most peak sun hours as the sun moves from east to west.

Temperature

When a solar panel gets warm, it affects how the electrons move in the solar cell. The warmer a solar panel becomes, the less efficiently it will transfer energy.

On average, the ideal temperature for a solar power panel is around 25°C. In the UK, it does not get too hot for solar panels, with average summer temperatures usually around 18°C – well within optimal parameters.

Final Thoughts

The number of solar panels required to power your fridge is simple enough to work out if you follow our guide and simple formulas.

As we discussed, there are many variables to take into account that determine your solar power output. These variables are best assessed and addressed by solar power professionals.

Contact us, from Eco Happy, to get a solar installation quote today. Our expert team will calculate exactly how much energy you will need to power your fridge. We will also help optimise your solar energy system to lower your electricity bills and ensure efficiency for a long time.

FAQs

What size solar panel is needed for a 12V fridge?

It depends on the energy consumption of the fridge. To run a refrigerator of 12V can require anywhere between 40 W to 200 W per hour. Additionally, solar panel output ranges between 250 W and 400 W per hour.

It also depends on your local weather conditions, if you have a storage battery in place and what your solar setup’s total energy efficiency is.

Can a 100-watt solar panel power your refrigerator?

No, a 100 W solar panel is not enough to run a refrigerator. If you have a single 100 W solar panel, a small fridge with an energy consumption of 100 W per hour, and your system has 100% energy efficiency, you would be able to run a refrigerator for approximately 12 hours.

However, this would also mean your panel receives 12 hours of peak sun hours, which is unrealistic.

How long will a solar battery run a refrigerator?

It depends on the size of the battery and the energy needed to run a refrigerator. To work out roughly how long a battery can power your refrigerator, take the power output of the battery and divide it by your fridge’s hourly energy consumption.

The average refrigerator runs the compressor to cool the unit for about 8 hours a day. This means that if you have a 200 W fridge, running for 8 hours, you would need a 1,600 W storage battery.