Summers can deliver very hot temperatures, and using A/C becomes a necessity to achieve the 68ºF optimal room temperature. The downside of A/Cs is the high power consumption which translates as expensive electricity bills.
Solar power can be a solution to enjoy air conditioning without expensive electricity bills. Photovoltaic (PV) modules are very powerful, and are capable of running A/C units, delivering enough power to cool rooms for several hours using solar power.
In this article, we go over some interesting information about running A/Cs with solar power. Here you will learn about different A/C types, how to calculate consumption for an A/C, and choosing the right PV system to power an A/C for as long as you want to.
Important Definitions About Air Conditioning
To understand the important technical information about A/Cs, we should first learn the basic concepts related to these cooling units. Here we will explain what is a BTU, what is a Ton, and what does EER/SEER means.
British thermal unit (BTU)
The BTU is the British thermal unit. This means the amount of energy or power required to raise the temperature in one pound of water by one degree Fahrenheit.
Air Conditioning Capacity (Tons or tonnage)
A tonnage (ton) is a unit that illustrates the ability of an A/C to transfer 12,000 BTUs in 1 hour. 1 Ton is equal to 12,000 BTU/hr., 1.5 ton equals 18,000 BUTs/hr., 2 tons equal to 24,000 BUT/hr., and so on. The kWh and tonnage can relate in a ratio of 1 kWh for each 3,412 BTU/hr., 1 Ton = 3.516 kWh.
Energy Efficiency Ratio (EER) & Seasonal Energy Efficiency Ratio (SEER)
The Energy Efficiency Ratio is the relation between BTU/hr. and power input in Watts for an A/C. The EER varies ranges from 5.4 – 12, a higher number means a better power efficiency. The Seasonal Energy Efficiency Ratio (SEER) is the same relation, but only considering summer temperatures instead of all seasons. The SEER is better for countries with extremely hot weather during summer.
What Are The Different Types Of Air Conditioners?
There are six commonly used types of air conditioners. These are the following:
Window Type Room A/C
Window A/C unis have all major components (compressor, condenser, evaporator, and fans) within the same casing. These A/Cs are partially installed inside the room and partially outside, using a hole in the wall or a window casing. Window type A/C handles 1 – 2 tons or up to 12,000 – 24,000 BTU/hr.
Split Type Air Conditioner
The Split A/C has two units, one installed inside and one outside. The outdoor unit encases the compressor and condenser, while the indoor unit has the fans, filter, and distribution components. The split A/C is less noisy, easier to install, and handles higher BTUs. Split A/Cs handle 1.5 – 2.5 ton or 18,000 – 30,000 BTU/hr.
Wheel units are transportable A/Cs requiring more room space and can be more expensive. They are suited for homes where split or Window A/Cs cannot be installed. Wheel A/C units handle 3.5 – 10 tons or 42,000 – 120,000 BTU/hr.
Compact Central Units
Compact central units are A/Cs installed partially outdoors, working as a larger central version of the split A/C. The outside unit encases condenser and compressor, while the inside unit has filters and a distribution system, delivering conditioned air to several rooms in the home. These units handle 3 – 16 tons or 36,000 – 192,000 BTU/hr.
Central Air Handling Units & Central Units
Central Air Handling Units & Central Units are large A/Cs similar to the Compact Central Unit. Central A/C units deliver 16 – 60 Tons or 192,500 – 741,700 BTU/hr, and Central Units 10 – 1600 tons.
What Is The Right A/C Tonnage For Your Room?
Choosing the right A/C is important to set a room to the right temperature with a properly sized A/C. To choose the right tonnage concerning the size of each room, use a simple thumb rule:
- 100 Sq. feet or smaller rooms, require 0.75 – 0.8 tons.
- 100 – 120 Sq. feet rooms require 1 ton.
- 120 – 160 Sq. feet rooms require 1.5 tons.
- 160 – 200 Sq. feet rooms require 2 tons.
For bigger rooms, adapt the tonnage by increasing 0.5 tons for each additional 40 Sq. feet. When choosing a central unit for the whole house, use this criterion by adding the size of each room to the calculation.
How Much Does Your A/C Consume During The Day?
To choose a PV system to run an A/C, you should know how much power the A/C consumes daily. Here we explain step-by-step, how to do this calculation by using a simple example with a 1.5Ton (18,000 BTU/hr) A/C unit with 16 SEER.
- Consider usage hours for the A/C, we will assume 8 hours.
- Calculate compressor operational time concerning the Cut-in & Cut-out conditions. We can estimate the compressor to be working nearly 70% of the time. This translates into a cooling energy requirement of.
3. Calculate daily power consumption concerning the A/C. This can be done by using the SEER value
Using this, you can calculate how much a home A/C consumes concerning its BTU/hr. or kWh. This allows you to pick the right PV system to run your A/C and save money on electricity bills.
Can Solar Power Run Your A/C Unit?
Solar energy transforms solar radiation into DC power by using PV modules or solar panels. This energy can be used directly or after being transformed into AC power, to run an A/C unit. Homeowners can also acquire larger PV systems with battery banks, to store excess generated energy at the batteries for cooling the home at nighttime, when the panels are not generating.
Solar panels can generate electricity throughout the whole day. The average solar panel power output during the day is equivalent to the PV modules generating 4 – 8 hours of power at maximum efficiency. The total power output for panels can vary depending on the solar index, which varies between states.
A 1.5 ton A/C running for 8 hours, consumes nearly 6.3 kWh daily. Living in a state that ensures a power generation equal to 4 – 6 sun peak hours at maximum efficiency, you will require nearly a 2kW PV system. This system produces enough energy to power the A/C during the day and for storing power to run the A/C for the rest of the 8 hours.
What To Look For In A Solar-Air Conditioning Kit?
There are many Solar-air conditioning kits available, these have PV systems adequate for running A/Cs for several hours. Here we go over some aspects to look for when acquiring a Solar-air conditioning kit.
The Tonnage Of The A/C Unit
The tonnage relates to the A/C capacity and should be adapted to the size of each room. Picking the right tonnage will ensure you get an A/C that sets the right temperature in no time.
Panels included in the kit
The panels included in the solar-air conditioning kit define the size of your PV system. You can expand this size, but we recommend you pick a kit with the right amount of panels for your A/C.
Does the kit include a battery bank?
If you want to run your A/C entirely off-grid, then you will need to include batteries into the equation, whether you want to run the A/C during the day or night. Choosing a previously sized kit with a battery bank included will save you time and compatibility issues that could come up by choosing the wrong batteries.
The capacity of the charge controller
The charge controller diverts the right amount of power between the battery bank and the A/C unit, you should consider the right capacity concerning the consumption of the A/C, the size of the PV system, and how much you want to expand this installation.
Running an A/C with solar power is entirely possible, practical, and advantageous since it will allow you to use air conditioning without increasing the power consumption for your electricity bill. While you can run any A/C with solar panels, we recommend you get a solar-air conditioning kit, which already includes all the right components to run the A/C unit with solar power.
If you decide to acquire the panels and A/C separately, remember to size the A/C to the room, calculate the consumption, and install the right solar system to run the A/C for as long as you want. By doing this, you can start enjoying a cool summer without stressing about high electricity bills at the end of the month.
Frequently Asked Questions
Many readers may have doubts regarding the use of solar power for running A/Cs. In our F.A.Q. section, we answer some of the most common ones regarding this subject.
Some states in the U.S. like Florida, Kentucky, Texas, New Mexico, and many others, will grant you rebates when acquiring a high energy efficiency A/C unit that meets certain conditions. For instance, getting a new A/C unit in Florida with a 16 – 17 SEER rating can make you eligible for a $150 rebate by FPL. You can look up rebates at your state in DSIRE or by asking your electricity provider.
It is possible to run an A/C for the whole day with solar power. The 1.5 ton A/C running for 8 hours, consumes about 6.3 kWh, running this A/C for the whole day, you would require a PV 19.8 kWh system and batteries to stores excess generated energy to be used at night.
When picking an A/C, look for the highest EER and SEER rates. A/C units with high power efficiency can run with fewer panels and consume less power to cool rooms at the right temperature. These A/Cs are a better investment when considering savings in power consumption for 1, 2, or more years.
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