How Many Solar Panels Are Required For a 12 V Air Cooler?

Air Coolers are widely used during summer in urban and rural areas of Pakistan.

And solar energy is the best alternative to run your cooler with a very small investment.

To put it simply, you need only one panel without an inverter to run a 12V DC air cooler.

Let’s look at how to figure out the right size of solar panels and the size of batteries needed to use solar energy at night.

What Types of Air Coolers are Available in Pakistan?

Portable Room Air Coolers

 These are compact and energy-efficient coolers suited for smaller spaces or personal use. 

It operates at 12V DC and has a wattage of nearly 70 W.

You can power it from your main (Wapda) using an adapter, but it is recommended that you run it directly on solar panels (without any inverter).

Room coolers have a plastic body and use honeycomb cooling pads, which are more efficient and longer-lasting than the traditional khus.

Window (Lahori) Air Cooler

Traditional air coolers (Lahori coolers) have a metallic construction and khus (a type of grass) windows for cooling.

They are generally affordable but require regular maintenance, such as changing the khus every year.

These run on 240 V mains supply and consume power equal to two ceiling fans, which is approx. 250W.

With the rising cost of electricity, these appliances are not suitable for lower-middle-class families as they consume more power.

Steps to Calculate the Number of Panels For Air Cooler

We’ll calculate the size of the panels for the 12V air cooler. First, we’ll have to calculate the daily energy required to run it, then the daily panel output, and finally, the size of the panels needed.

Determine Daily Power Consumption of the Air Cooler

Assuming the air cooler runs for about 7 hours a day, the daily power consumption is calculated as:

Daily Power Consumption=Power Rating×Hours of Use

Daily Power Consumption = 70W × 7h

Daily Power Consumption = 490Wh or 0.49 kWh  

Estimate Solar Panel Output

Most solar panels in the market have an output rating between 350 and 600 watts.

For this calculation, we can use an average panel output of 250 watts.

Assuming an average of 5 peak sunlight hours per day, the daily energy output of one solar panel can be estimated as follows:

Daily Energy Output=Panel Wattage × Peak Sunlight Hours

Daily Energy Output= 250W × 5h

Daily Energy Output = 1250Wh or 1.25 kWh

Calculate the Number of Panels Required

Now, to find out how many panels are needed to meet the daily power consumption of the air cooler:

Number of Panels = Daily Power Consumption / Daily Output Per Panel

Number of Panels = 490Wh / 1250Wh

Number of Panels ≈ 0.4

Since you cannot have a fraction of a panel, you would need at least 1 250 W solar panel to run the 70W air cooler for 7 hours.

Number of Panels Required for AC Cooler (Lahori Cooler)

Following the same procedure, we can calculate the panels for this window cooler with a wattage of 250 W.

So a 500 W solar panel would be enough to run this cooler.

But keep in mind that we also need an inverter for this cooler because it runs on AC power.

I will not recommend it because of the higher inverter costs. However, if you need it for a larger cooling space, you can power it with a locally-made UPS instead of an inverter.

What Battery Size is Required for a 12V Air Cooler?

There are dry and tubular batteries on the market, but tubular batteries are best suited for solar setups with a 50% discharge rate.

Determine Required Battery Capacity

It’s common to use only 50% of the battery’s capacity to ensure the battery lasts and to avoid deep discharging (which can harm battery life).

Thus, the required battery capacity can be calculated as follows:

Required Battery Capacity = Daily Power Consumption / Depth of Discharge 

Using a depth of discharge of 50%:

Required Battery Capacity= 490Wh / 0.5

Required Battery Capacity = 980 Wh

Convert to Amp-Hours (Ah)

If using a 12V battery, we can convert watt-hours to amp-hours using the formula:

Battery Capacity Ah = Battery Capacity Wh / Voltage 

Battery Capacity Ah =980Wh / 12V

Battery Capacity Ah ≈ 81 Ah

For sufficient capacity, consider a battery rated at least 100 Ah, as the nearest rated battery in the market is 100 Ah.

Can I Run Air Coolr Directly From a Solar Panel?

The 12 V DC cooler (discussed above) can operate directly on solar power without an inverter, which is why I recommend it for home use.

While a traditional window cooler that runs on AC main supply cannot operate directly on panels. And you need to arrange an inverter to convert the panels’ DC current into AC.

Concluding Words

With just one 250 W solar panel, you can power your cooler during the day for 7-8 hours. While a properly rated battery can keep it running through the night.

This setup not only reduces reliance on electricity but also ensures you stay chilly without worrying about rising energy costs.

Frequently Asked Questions