Running your home appliances with solar panels is a great environmental option. You can power most of the devices in your home very easily with solar panels.
These appliances pull a constant current. When you know the power rating of the appliance, then you can just match this with the power output of your solar panels.
However, some appliances, such as freezers, refrigerators and air conditioners, aren’t so easy to calculate because they run with motorized compressors.
This means that the appliance’s power that is drawn can vary which causes problems with solar panels.
We find out how to overcome these issues, and how many solar panels you really need to run your air conditioner.
How Many Solar Panels Do You Need To Run Air Conditioner?
An air conditioning unit typically needs around 1,200 Watts in tons from solar panels to run. This is based on an irradiance sun exposure level of 4 hours per day.
You will also need a 100 Ah battery to store the electricity that the solar panels provide. This will ensure that when there is cloud cover, that your air conditioner is still running efficiently.
However, each air conditioner unit has its own individual requirements. Let’s take a look at the details of what you need to know for powering your air conditioner with solar power.
Can You Run An Air Conditioner Off Solar Panels?
Before we find out more about the connection between solar power and air conditioner, let’s see how an air conditioner works.
Some appliances are run with DC load. This power rating is calculated by multiplying Volts with Amps. This provides a result in Watts.
The majority of your home appliances are run with AC load, including air conditioners.
They run with AC circuits, and when you try to apply the same formula (Volts x Amps), then this does not always return a wattage as the supply varies.
Therefore, AC power calculations will need to consider the current waveforms and voltage.
Most of your home appliances use AC power, and therefore you need to calculate the power output in a different way.
If your appliance’s I and Vi output are at their maximum at the same time, then they can equal true Watts.
How Much Electricity Does A Solar-Powered Air Conditioner Use?
All air conditioners are slightly different in their technology and efficiency. This is why air conditioning units are typically rated in tons rather than in kilowatt.
A ton of cooling power indicates the cooling required to melt around 2,000 pounds of ice per day. The greater the cooling capacity, the more cold air the conditioner unit will put out each hour.
One ton of an air conditioning unit can also be converted into 3.5 kW.
Another factor in the energy output of an air conditioner is the EER value. This is the energy efficiency ratio which indicates how efficiently an air conditioner can cool the air.
Modern air conditioning units have a typical EER of 10 or 11. It is recommended to use an AC unit with an EER rating of a minimum of ten in locations with a hot climate.
The general EER is based on an outdoor temperature of 95 degrees Fahrenheit, an inside temperature of 80 degrees Fahrenheit and a humidity of 50%.
In the past years, another rating has become very popular: SEER. The SEER rating takes into consideration the various season temperatures outdoors.
How Much Does It Cost Per Hour To Run An Air Conditioner?
There is a large range of factors to consider when looking at the overall costs of an air conditioning system.
You need to take into consideration how efficiently the AC unit is running, how often you run it, the outside temperature, the price of kWh of your electricity and the outside temperature.
Solar panel installers and air conditioner professionals use a generic rule book when it comes to sizing.
One rule states that an air conditioner pulls roughly 7 Amps for every 1 Ton of cooling capacity.
The power requirements will change with the individual tonnage. For example, for two tons there is a 15 Amps pull, for 4 tons there is a 21 Amps pull.
This is a really solid guideline for all DIY solar projects and home appliances, such as air conditioning units, that you may want to plug in.
It’s important to mention here that on the label of your air conditioning unit there are a number of different figures listed.
You will find that the RLA (rated load Amps) is not your typical AC current. The RLA is the maximum current that the compressor motor inside the AC unit needs to function.
Additionally, there is also an LRA value (locked rotor Amps) which is displayed when the motor has stalled and does not rotate anymore.
The LRA value is the same as the surgeon inrush current. This is the current which is pulled when the motor starts up from a standstill.
With a lot of appliances, they pull slightly more power when they start from cold. The same applies to an air conditioning compressor motor.
In fact, this motor can pull up to four times more power than when it is starting up from cold. This is called the inrush current or surge current. It is indicated with the highest Amps that the motor can pull
This means that an air conditioner may need a significant amount of solar panels to balance the power requirements.
As installing a large amount of solar panels as part of your solar system is impractical, you should make sure that you install a number of storage batteries.
They will ensure that you have extra power when the AC unit encounters any issues or when there is no sun.
You will not only need to take the solar panels into account, but you also need to ensure that the sizing of the wiring is correct.
This should be based on the maximum current of the unit, plus 10% extra.
A surge current typically only lasts a very short time, and this does not affect the wiring significantly.
However, you will need to take this into account when planning your solar setup for your AC units.
You will also need to consider any fuses and breakers which need to be the correct size to allow for a surge without tripping.
In addition, this can have an impact on any solar system that you may want to install to run your air conditioners.
If you run your solar panels with air conditioners only over the day, then you will need to allow for this surge, which can be difficult without a battery storage backup.
The best option is to install an inverter which turns the direct current from the solar panels into AC current that your home appliance need to run.
This is often one of the most overlooked issues: solar panels produce direct current (DC), while home appliances use alternating current (AC) to work.
You can only overcome this issue by installing an inverter.
How Many Solar Panels Do You Need To Power Your AC Unit?
As you now know what happens inside your air conditioner and what electricity it needs, let’s explore the power supply from the solar panels.
The most common solar panels are 300 Watts panels, so we use this as a base for our examples below.
The exact output of a solar panel depends on a lot of different factors, including the solar panel area, its age, efficiency, the sun’s energy at your specific location, the orientation of the panels, and the outside temperature.
Solar panels are typically tested in laboratory conditions which do not represent your individual home conditions.
The average solar panel assumes a solar irradiance of 1,000 Watts per square meter, and an outside temperature of 25 degrees Celsius.
Laboratory conditions also assume that a solar panel is at a 90 degrees angle to the sun. For most homes, this is impractical and almost impossible to do.
That’s why, you can assume that there is a reduced efficiency, depending on the angle to the sun.
Equally, when the outside temperature is above 25 degrees Celsius and your local irradiance levels are lower, then the panels’ output will decrease significantly.
How Many Solar Panels Do You Need To Run A 5 Ton AC Unit?
The majority of air conditioning units are run only for around four hours a day.
They are typically used around noon which is an ideal time because that’s when the sun is at the perfect angle for the maximum solar output.
One ton of cooling capacity from your air conditioner is roughly 1.2 kW. This means that when you run your unit for four hours, then it will pull 4.8 kWh in that time.
This means that a 5 ton air conditioner will pull 24 kWh.
A typical 200 watt solar panel can produce maximum 300 Watts. Over four hours, this adds up to 1.2 kWh.
In order to calculate the correct number of solar panels you need for your AC unit, you will need to divide the AC’s energy consumption (24 kWh) with the produced energy from your solar panels (1.2 kWh).
This results in 20 solar panels that are rated with 300 Watts.
However, it is important to note here that the majority of solar panels do not put out exactly this wattage (for the reasons mentioned above).
Laboratory conditions aren’t the same as real live conditions, so you will need to make an allowance of around 10% for any losses.
How Many Solar Panels Do You Need To Run A 2 Ton AC Unit?
If you ignore any surge currents, you can apply the above calculation also to a 2 ton AC unit.
If you run your air conditioner for 4 hours in the middle of the day, when you get a result of 8 solar panels (300 Watts rated).
Can You Power A 1.5 AC Unit With Solar Panels Only?
Just like any appliance, smaller units are always much easier to power. With the same calculation as above, you can power a 1.5 ton air conditioner for four hours per day with six 300 Watts solar panels.
Yes, it is possible to power a 1.5 AC unit without batteries but you will need at least six solar panels and four hours of solid sunshine.
Can Solar Panels Run Your AC Unit During A Power Outage?
One of the biggest concern with owners of solar panels is what happens when you have a power outage.
If you do not have a storage battery hooked up to your system, then the air conditioning unit may stop working during a power outage.
As solar panels do not store energy, they will just send it straight to your air conditioning unit, and if you do not back any backup solutions for your AC to run, e.g. a battery, then it will stop working.
This means that, if you want to keep your home appliances running during the night or a specific power outage, then you need a backup battery or alternatively a power generator.
What Are The Disadvantages Of Using Solar Panels For Your AC Unit?
Solar power has many great advantages and benefits. It can save you money and it allows you to be less dependent on the general power network.
However, you will find that the purchase and installation of a full solar system can be expensive.
You will need to weigh up whether you want to spend this amount of money for running your air conditioning unit for just a few hours per day over a limited period in the year.
In addition, solar panels do rely very much on good weather and direct sunshine. If you are in a sunny location, then this may be more suitable than being in a cooler climate where it’s cloudy most of the time.
It’s important to consider these factors before buying a solar panel system.
Powering your air conditioners with solar panels is generally a good idea. Solar panels are efficient and good for the environment.
However, there are some disadvantages that you will need to consider when running your AC units on solar power.
Make sure that you live in a sunny location which provides the most sunlight for your panels.
You will also need to ensure that the installation of your solar panels is done professionally and to a good standard.