Do Air Conditioners Use and Run on AC or DC Power?


Many people ask me if their air conditioners are AC or DC. So, I did some research to find out their differences.

Most air conditioners use AC instead of DC. Air conditioners' main power supply requires AC or alternating current to operate. Some air conditioners do use DC or direct current but, they are usually for low power applications.

DC air conditioners are getting popular and they are often associated with high-efficiency and energy-saving. Actually, what is DC air conditioners, and what's the difference?

What is DC Air Conditioner?

DC air conditioner is also known as DC inverter air conditioner. A DC air conditioner is an alternative name for an inverter air conditioner. But, why call an inverter air conditioner a DC air conditioner?

As you may have noticed, the name DC air conditioner comes from a portion of the inverter process where it converts AC to DC. But, why the inverter converts AC to DC and then convert it back from DC to AC?

An inverter converts AC to DC so that it can change the frequency of the resulted AC. By changing the frequency of its output AC, it can control the speed of the compressor. One of the benefits of controllable compressor speed is achieving higher efficiency.

How Inverter Control Compressor Motor Speed?

The air conditioner is designed to use AC. Thus, the inverter controller mimics the characteristic of AC by manipulating the DC current flow. During the process, the inverter controller can change the way it manipulates the DC current flow and therefore, controls the compressor motor speed.

If you wish to know in great detail how each component works together to control compressor motor speed, the below video from The Engineering Mindset is a very good one.

In summary, a DC air conditioner or inverter air conditioner converts AC to DC in order for the inverter controller to be able to manipulate the frequency of its output AC and therefore, controlling the speed of the compressor. Without the inverter, there is no way to control the speed of the compressor.

Solar Air Conditioner and DC Motor

There are two types of solar air conditioners. One is the modification of a conventional air conditioner, the other one is a ground-up new design just for solar power application.

Solar power produced from solar panels is DC or direct current, just like batteries. In order to use solar power to operate conventional air conditioners, a solar inverter is required to convert DC to AC. Remember that conventional air conditioners require AC or alternating current.

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On the other hand, there are solar air conditioners that are redesigned such that their fan motor and compressor run on DC. Meaning that these air conditioners can run on DC without an inverter. They do not require an inverter to convert AC to DC.

Because these solar air conditioners run on DC, they are often designed to be solar-powered only. However, a separate inverter usually is recommended so that in case there is no solar power, the inverter can convert the house AC supply into DC and keep the solar air conditioner running.

Redesigned air conditioners with DC motors offer great energy efficiency. The DC motor alone is 30% more energy efficient than the conventional AC motor according to Machine Design. However, these types of DC air conditioners are usually only for low-power applications.

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Are DC Air Conditioners More Efficient?

On average, DC air conditioners are more efficient than the conventional AC air conditioner whether it is inverter type or solar-powered type.

Inverter air conditioners control the compressor speed according to the heat load, optimizing the cooling capacity of the air conditioner and achieving higher efficiency.

Solar air conditioners utilize solar power. Although during the cloudy days they require a house power supply, solar air conditioners still provide significant power saving from day one.

Unfortunately, both inverter and solar air conditioners are much more expensive than conventional air conditioners especially with solar air conditioners where you'll need a few pieces of solar panels and some electrical work to be done.

With solar air conditioners, you are advised to calculate the return on investment if it is acceptable for you. On the other hand, an inverter air conditioner usually costs about 20% to 30% more expensive than a conventional non-inverter air conditioner. But, inverter air conditioners usually worth the money.

Can Air Conditioner Run on Battery?

Both inverter and non-inverter air conditioners can't run on a battery. Non-inverter air conditioners require an AC power supply and battery supplies DC power. Thus, non-inverter air conditioners unable to operate.

Although inverter air conditioners convert AC to DC in the process, their main power supply still requires AC. Air conditioners require AC because of high power consumption. DC is usually for low-power applications.

On the flip side, the solar air conditioner can run on a battery. In fact, solar air conditioners are designed to run on a battery because solar power is not available 24/7. Batteries are often included in a solar air conditioning system to provide power when solar is not available.

In addition, some other mini air conditioners also can run on battery such as air conditioners for RV, personal air conditioners, and camping-use air conditioners. These air conditioners are low-powered and designed to run on a battery. They are low in cooling capacity when compared to conventional air conditioners.

Is Your House AC or DC?

Almost all houses are equipped with an AC power supply. Large appliances such as air conditioners, water heaters, refrigerators, washing machines are high power consumers and run on AC.

Small appliances such as TVs, phones, internet routers, and laptops are low-power consumers and run on DC. Therefore, these small appliances require a power inverter to convert AC to DC. Fortunately, these small appliances already come with a suitable power inverter.

So, you no need to worry about it unless you are buying an appliance from overseas, you'll need to double-check the electrical requirement for that appliance.


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Yu Chang Zhen

I enjoy working on air conditioners and ventilation fans because Malaysia is a very hot country.

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