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How Many Solar Panels to Run Air Conditioner?

You can’t deny the great feel of cool air conditioning in your home, especially in the Summer.

But, this cool air comes at a price. The cost of running an air conditioner can drain your pockets.

It’s only natural to wonder if you can use solar panels to power your AC. Your next question would then be, how many solar panels to run an air conditioner?

In this guide, we’ll answer this question to help you keep your air conditioner running without having to break the bank.

Why Solar?

how many solar panel to run ac

Although AC cooling sounds good, it releases tons of carbon dioxide into the atmosphere.

Unfortunately, carbon dioxide, as a greenhouse gas, pollutes the environment. The result is hotter earth. So, you end up with a cooler home but a not-so-cool Earth. Therefore, it is best to use solar.

Solar air conditioners work the same way as standard ACs. The only difference is what powers them – the sun.

Decide Off-Grid VS. On-Grid System

on grid vs off grid solar

You can either decide to connect your solar panels to the grid to power your AC.

The grid system’s advantage is that your AC can still run even at night or on a cloudy day.

This system doesn’t require batteries because you pull the power from the grid.

On the other hand, batteries are necessary for the off-grid solar system. The batteries will also keep your AC running even at night because they store the energy.

Off-Grid VS. On-Grid System
on-grid solar system

What Determines Your AC Power Consumption?

To determine how much energy an AC uses, you have to consider factors like the model, where you live, and the weather.

How Many People Are in a Room?

Because people emit heat, the more people there are in a room, the higher the AC consumption rate. Imagine a room with eight people and one with 15 people. The room with 15 people will need a bigger AC or more than one AC to cool it.

What is the Temperature Outside?

On a hot day when the temperature is, say, 42 degrees Celsius, the AC will use more power to cool down than when it’s 30 degrees Celsius.

How Many Electrical Appliances Do You Have?

Your AC has to work harder to cool a room that has many electrical appliances.

Where Do You Live?

If you live in Colorado, you probably have higher cooling needs than a person in Texas.

Another consideration under “location” is whether your home is shaded or not. If your house is exposed to the sun, your cooling needs will also be higher without trees or any other shade.

Cooling degree days by census division
“Cooler” colors indicate more cooling degree days, leading to more demand for air conditioning Source: U.S. Energy Information Administration

How Many Windows Do You Have?

While windows are suitable for letting air in and out of your house, they are a crucial determinant for an AC size.

When it’s hot, windows let in the breeze to keep your house cool in the Summer. However, in Winter, you can lose so much heat through windows, pushing up your AC needs.

Calculating the Power Consumption of an AC and Cost

solar panels to run air conditioning

How To Do it Manually

To establish the cooling capacity of an AC, consider the calculations of the amount of heat energy it removes from a room.

To correctly calculate the AC power usage, you will need to find out:

  1. The AC wattage– This means the rate of power consumption per hour
  2. Hours in use– Consider the number of hours the AC is running
  3. Electricity tariff– Establish how much your electricity provider charges you per unit

An average American household uses 318 watts per hour, adding up to 228 kWh monthly.

Therefore, if you calculate at an electricity rate of $0.12 kWh:

228 kWh x $0.12 = $27.36

AC comes in different tons of cooling. For instance, you can have 1 ton, 1.5 tons, 2 tons, or 3 tons of cooling. For instance, a 1-ton air conditioner uses between 991 and 1,333 watts. Therefore, the energy consumption in a month is between 92 and 122 kWh.

In terms of costs:

On the lower side, 92 kWh x $0.12 = $11.04 monthly

Alternatively, ACs come with an energy-saving label that can help you do the consumption math.

Using a Kill a Wattmeter

If you want to accurately measure any household appliance’s power consumption without going the manual way, use a Kill A Watt meter.

You first plug your AC wire into the meter. Then, connect the meter to a wall socket. Lastly, get the AC running. Study the meter for up to seven days for best results. At the end of the week, make a reading of the final value.

Now, to Determine the Number of Panels

solar panels to run air conditioner

After figuring out how much electricity your AC consumes, you know the solar panels you install must match that consumption.

Let’s say you have a one-ton AC. On average, if you install a central AC, it will use between 3kW and 5kW of electricity. Your solar panels, therefore, have to generate at least 3kW of energy for effective cooling.

Using the same example, if you want solar panels that can power your AC, then you can install thirty 100-watt solar panels.

10 x 300w = 3,000w (3kW)

Another example,

If your AC uses 5,000kWh yearly, you need solar panels to generate the same amount of energy.

Therefore, divide this consumption amount by the average energy a solar unit is likely to produce.

Solar panel  production ratio by region

Region

Typical Production Ratio Range

Southwest (e.g. TX, NM, AZ)

1.5-1.8

West Coast (e.g. CA)

1.4-1.8

Mountain West (e.g. UTC, CO)

1.3-1.6

Southeast (e.g. FL, GA, NC)

1.2-1.5

Mid-Atlantic (e.g. MD, DC, PA)

1.1-1.35

Midwest (e.g. MN, IL, MI)

1.1-1.3

Northeast (e.g. MA, RI, CT)

1-1.3

Pacific Northwest (e.g. OR, WA)

1-1.15

For instance, if the production ratio in California is 1.6, then you’ll need 3,125w.

5,000kWh/1.6 = 3,125

But, if you live in Rhode Island, your requirement will be 4,167.

5,000kWh/1.2 ≈ 4,167

Then after getting the number of watts required, divide this by each panel’s wattage. Bear in mind that solar panels are in various sizes. For this example, let’s say you have 350W panels.

So, the number of panels you need if you live in California will be eight to run your AC.

3,125kWh/350W ≈ 9

How Long Can Your AC Be On Solar Power?

If you use the above case, your AC can run for about five hours max.

But, this time could also be affected by other factors such as the panels’ location, the weather, or even whether your AC is in good shape.

Therefore, if your AC is usually running longer than this time, get a three to four-kilowatt system.

What About Batteries

Several batteries (solar battery bank) will supply the AC with the power it needs.

You can get these batteries for 40% of the whole solar system’s cost, hence an additional cost.

Types of Solar-Powered Air Conditioner

solar panel to run ac

You can choose from three types of solar air conditioners. They include:

DC Solar Air Conditioners

You can connect these types of air conditioners directly to the panels without conversion. You can only add batteries to these ACs if you have extra energy. On the upside, maintenance is easy.

However, on the downside, this type of AC requires batteries and an inverter when there is no sunlight.

Therefore, they are not the best off-the-grid, especially at night.

AC Solar Air Conditioners

They are also known as inverter ACs. This type of ACs needs an inverter to convert DC to AC energy.

You can also add batteries to this plan to store excess energy.

The beauty of this option is that it’s cheaper than a majority of the DC options. With this option, you can still power the AC by pulling electricity from the grid on overcast days.

Hybrid Solar Air Conditioners

You can directly get power from the sun during the day or use an inverter at night. However, you don’t benefit from net metering. The advantage of this AC is that it does not need batteries.

Can You Install Air Conditioners in a Home Already Powered By Solar?

If your home already has a solar plan, it doesn’t lock you out of going solar with your AC. You can always check if you have some remaining space to install additional panels. That is if the panels you have can’t power all your appliances plus an AC.

Unfortunately, if you don’t have more space on your roof for additional panels, the only option is energy efficiency. You can do an energy audit of your home to see how you can lower your power consumption.

how many solar panels to run ac unit

Final Thoughts

You don’t have to bear with the uncomfortable Summer heat to avoid turning off your AC. Or the cold Winter days. Also, you don’t have to run into high costs when cooling or warming your home. Why not power your AC with solar?

Now that you know the answer to how many solar panels to run an air conditioner, you can rest easy. It’s simple. Firstly, you decide whether you want to go on-grid or off-grid. Secondly, calculate how much power your AC consumes either manually or using a kill a meter.

Finally, by using your panel’s production and your AC energy needs, determine how many panels you require. Suppose you’re not a first-time solar user, the better. All you have to do is increase the number of panels on your roof to accommodate the AC.

Don’t suffer under the sweltering heat or chilling cold any longer.

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