Most people would agree that shifting to solar power systems is a great decision. You depend less on your utility company, improve your energy consumption habits, and of course, positively impact the environment. But many times, getting your power from solar means you’ll need extra thought to run your home appliances and enjoy a comfortable lifestyle. For example, figuring out how many solar panels do you need to run air conditioning.
Especially during the summer. While this season is ideal for solar power systems thanks to the increased amount of sunlight, there’ll also be high temperatures you have to fight back with electric appliances. Most likely, air conditioning.
To ease your mind, is it possible to power an air conditioner with solar panels? Yes, sorting out a few things first, like how many solar panels you need to run an ac.
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AC Star Ratings and Their Meanings
Let’s start with the AC star ratings. You likely have seen the stars on your AC unit, and the truth is, all energy-conscious people should know what they are and mean. Star ratings are very important as they help you estimate the cooling efficiency of your air conditioner. In other words, it helps you know how much power does an ac need to run.
The star rating takes two parameters into account to determine the efficiency of air conditioners:
- The cooling capacity, expressed in British Thermal Units (BTU)
- The Energy Efficiency Rating (EER), which is the amount of cooling air conditioners can provide using a certain amount of power
The star rating of an AC ranges from 1 to 5. The higher the number of stars, the greater the efficiency of your AC will be, meaning your AC will give more output with lesser input power.
To give you an estimate, here’s a chart with star ratings of a 1.5 ton AC unit.
| Star rating | EER | Cooling Capacity (watts) | In/out Power (watts) | Units consumption/day (kWh) |
| Base star | 2.5 | 5200 | 2080 | 17 |
| 1 | 2.7 | 5200 | 1926 | 15 |
| 2 | 2.9 | 5200 | 1793 | 14 |
| 3 | 3.1 | 5200 | 1677 | 13 |
| 4 | 3.3 | 5200 | 1576 | 13 |
| 5 | 3.5 | 5200 | 1486 | 12 |
The Challenges of Running Air Conditioning With Solar
Like many other appliances, air-conditioning runs for several hours a day and night. This is a challenge for solar-powered houses, especially at night. As you know, solar panels only produce power when they’re receiving sunlight, something that doesn’t happen at night.
Still, running an AC at night is possible with solar energy. You just need to produce extra power during the day and store it to run your AC later at night.
You have two ways to store the extra energy your solar panel produces: grid-tied systems vs. off-grid ones.
The main difference between these systems is where the extra energy goes.
Grid-tied solar systems use a net metering mechanism that allows homeowners to store the extra energy their solar panels generate in the grid. That way, homeowners can store as much power as they want in the grid and use it later at night to run the ac. Another benefit of grid-tied systems is that you can draw power from the utility grid to run your appliances if your solar system fails.
With off-grid systems, homeowners don’t have a connection to the utility, so they can’t rely on it for storing or drawing energy. This situation makes banks of batteries an essential component for homes with off-grid solar installations. Batteries allow homeowners to store the extra power their solar panels produce and use it at night. If this is your case, there are two main types of batteries: lead-acid batteries and lithium-ion.
How Many Solar Panels Will You Need?
Time for the million-dollar question. How many solar panels you need to run air conditioning is influenced by variables like shading, altitude, and square footage of your home. These last two play an essential role since the altitude affects the performance of solar panels and air conditioners, while the “size” of your home determines the size of the AC.
But to make things simple, everything comes down to how much power your appliance consumes and how much your panel produces. Air conditioners use different wattages depending on their function and action. However, most houses have one-ton AC units installed, and on average, these consume about 3600 watts per hour or 1.3kWh.
On the other side, you’re likely to have installed a standard-sized residential panel, which, under optimal conditions, has an output of around 250 watts per hour, or 2kWh to 4kWh. Moreover, 2/3 of the US receives around 5,000 watt-hours of solar energy, so your solar panels will produce enough to cover the demands of a 3600-watt AC.
Now that you have all the numbers, you can calculate exactly how many solar panels to run air conditioning at your place by simply dividing 3600 by 250. This means you’ll need to set up 15 solar panels to run a 3600-watt AC.
Remember, this is just an estimate as the energy output of your solar panels may vary according to other factors, so you may need additional panels to keep the AC running at night.
(Read Also: How Many Solar Panels Do You Need to Run a Refrigerator?)
This information should help you to have an idea of what are the most important factors to consider when running air conditioning with solar energy at your place. More importantly, you should be able to calculate how many solar panels you need to run an AC.
Don’t forget to check ac star ratings as well. These are extremely helpful for energy-conscious people since they allow them to consume less power from the energy storage and save it for other appliances. Getting the most out of your solar power system is all about the efficiency of your solar panels and appliances.