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Solar Powered Air Conditioners: Are They Worth It?

When it comes to solar photovoltaics (PV), Australia has the highest penetration of rooftop solar in the world. 

Yes, that means that solar energy has gained a lot of traction among end users! With total power generation from rooftop solar close to 20 GW, using solar-powered air conditioning makes a lot of sense.

Now, you may wonder, can solar panels power an air conditioner in the first place?

The answer is yes. Not only will an air conditioner run by solar power help reduce energy bills, it will reduce carbon emissions as well.

So, let’s start by understanding how an air conditioner can actually run on solar power.

What is a Solar Air Conditioner?

Solar powered water heater and air conditioner on a roof of a building

In terms of the way it operates, a solar air conditioner functions the same way as a standard air conditioner. In both cases, the primary mechanical component is the compressor that works on the refrigerant. 

However, while a standard air conditioner runs on grid energy, a solar air conditioner feeds on solar energy. The solar energy captured by the solar panels is stored in a battery which powers the solar air conditioner.

Now, most solar aircons have a double diet and can function on grid energy as well. This will allow it to keep functioning if solar energy is not available or there isn’t enough of it – like when there’s a series of rainy or cloudy days or during system maintenance.

Now, you can make the necessary changes in an existing split AC or a central AC to make them run from solar panels. For new solar AC installations, you have three options to choose from.

The first choice is a DC solar air conditioner, where the output from the solar panels is being used directly. Such systems are easy to install and they can go entirely off-grid. The idea of setting up an off-grid solar-powered air conditioner and getting rid of power outages and power bills is tempting, right? 

Plus, this is the most eco-friendly option you can choose.

One disadvantage is that such a unit is incompatible with the grid. That means you will need a hefty battery to store energy and power the unit at night.

The other option is to use an AC air conditioner that uses an inverter to convert the DC power generated by the solar panels into AC. These units can be tied to the grid and you can even divert any excess solar power you generate back to the grid. On the downside, AC systems are less efficient than DC systems.

The third option is using a hybrid air conditioner that can run on both AC and DC. It will run from a battery during the day, and at night you can plug it into a normal AC outlet. While these systems offer incredible flexibility, the initial investment is on the higher side.

Ultimately, the choice depends on individual preferences. Since each system has its pros and cons, you might consider consulting a solar expert before making the final choice.

How Many Solar Panels to Power an Air Conditioner?

The number of solar panels needed to run an air conditioner will depend on the capacity of the system. Another factor that will determine the number of panels needed is the output of each panel. Keep in mind that smaller split units consume less power than central air conditioners.

Coming to the numbers, a one-tonne split AC will consume anywhere between 1200 to 1500 watts of power, depending on its energy efficiency. If your rooftop solar unit generates 250 watts per panel, you will need six panels to power the unit. In case you have higher capacity 400W modules, you will need fewer panels.

The maths is simple: the higher the tonnage, the more solar power you will need to generate. If you have an existing solar array, you will have to add extra panels to power up an additional AC unit. The overall cost will depend on the quality of the panels.

Then again, the cost of the panels is not the only consideration. You need to consider the battery size you will need to run the air conditioner on cloudy or rainy days. Since heating is mostly needed in the evenings, you will need to use a solar battery or connect to the mains for that. Also, the number of batteries will depend on the wattage of the unit. 

For hybrid units, you will have to consider the cost of the indoor and outdoor units, and the inverter as well. The rough cost for setting up a 3kWh solar air conditioner can be around $4,000. On top of that, there will be labour charges.

On the face of it, the idea of installing a DIY solar-powered air conditioner can be appealing. More so since it helps you reduce upfront costs. While it is definitely possible, there are a few things to keep in mind.

Installing the unit and making the necessary connections with the panel array requires in-depth knowledge of how electrical systems work. Besides, you will need to handle the connectors, batteries, and inverters in line with the local safety regulations. From that aspect, getting it done by a certified installer ensures peace of mind.

Pros of Solar Air Conditioners

The biggest savings from a solar air conditioner will be in the form of a drop in your energy bills. For a typical home, 30-45 percent of energy consumption goes for cooling or heating. Considering the total energy savings, the system will pay for itself in a few years. The exact savings will depend on the size of the solar setup and the amount of time the unit is used.

It turns out that investing in solar power is more practical if you have an air conditioner that is more than 10 years old and has low energy ratings. Replacing that with a solar air conditioner will improve your home’s energy efficiency significantly.

Not to forget, a solar aircon system is more environment-friendly and will reduce the carbon footprint of your home. Quite simply, every time you use renewable energy sources, you are reducing the use of fossil fuels.

Frequently Asked Questions

Is solar AC different from normal AC?

The internal functioning of a solar AC is the same as that of a normal AC. The only difference is that it runs on solar power while the normal AC runs on grid power.

Is solar AC worth buying?

Considering that a solar AC is environmentally friendly and helps to cut down on power bills, it is worth buying. In fact, you’ll certainly break even – but don’t expect it to happen in a mere year or two.

How many solar panels do I need to run an air conditioner?

The number of solar panels your aircon needs will depend on three factors:

  1. How much power the AC unit consumes, 
  2. How much you use it, 
  3. Finally, how many solar panels you have and how efficient they are.

As a rule of thumb, for running a 1.5-ton AC, you will need between 5-12 solar panels, depending on their capacity.

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