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To run a 5000 BTU AC you have to figure out its power consumption, your daily usage and how many solar panels are needed. Solar panels alone will not run an air conditioner however, so you have to get batteries, an inverter and a charge controller.
600 watts of solar power can run a 5000 BTU/450wh air conditioner for 7-8 hours a day. To complete the system you will also need 4 x 100ah 12V batteries, a 30A MPPT charge controller and a 1500W pure sine wave inverter.
How Many Watts Does a 5000 BTU AC Use?
The average 5000 BTU AC uses 450-500 watts. More energy efficient models draw 400-450W while other models use up to 630W. However, its energy usage is not necessarily going to be the same as its power consumption because AC units do not run all the time.
Suppose you have a 5000 BTU air conditioner and run it for 6 hours a day. If its power usage is 500Wh (watt hour), that suggests a power consumption of 3000 watts (500 x 6 = 3000).
However, air conditioners do not run continuously. The system runs at full power on startup, but once the room has cooled it shuts off. The unit comes on again to stabilize the temperature, similar to how a fridge works.
How often an AC goes on and off depends on its efficiency, room insulation and temperature. Since a lot of factors affect its duty cycle, you should use a Kill-A-Watt device to determine its power consumption.
How Many Solar Panels to Run a 5000 BTU AC?
A 600-700 watt solar system is needed to run a 5000 BTU AC. With this you can run the air conditioner continuously for 7-8 hours. However, performance will depend on how much sunlight your solar panels get.
For instance, suppose you have a 5000 BTU AC and want to use it for 8 hours a day. The unit uses 400 watts an hour.
That comes up to 3200 watts (400 x 8 = 3200). A 600W solar panel system can theoretically produce up to 4200 watts with 7 hours of sunlight per day (600 x 7 = 4200). With system losses, the number will be less than that, but still enough to run a 400wh AC.
To get the best results you should get high quality solar panels that can produce consistent results. A good choice would be the Renogy 100w solar panels. With six or seven of these you can run a 5000 BTU AC without issues.
As pointed out earlier, air conditioners have on/off duty cycles and are more efficient than ever. So it will probably use less than 3600 watts. But solar panels cannot produce their rated power continuously due to solar irradiance and limited peak sun hours.
Why Solar Panels Do Not Always Reach Peak Capacity
Have you noticed that your 100 watt solar panel does not always produce 100 watts? That is because the rating – whether it is 100, 200, 300 watts – refers to the maximum output. It does not mean the panel can produce that power continuously.
Solar irradiance is one of the methods used to test solar panel efficiency. The standard is measured in 1kw / square meter (or 1000W / square meter) of sunlight. A solar panel rated at 200 watts means it can generate 200 watts if it gets 1kw / square meters of sunlight.
The amount of light solar panels get changes throughout the day, the seasons and through constant weather fluctuations.
The easiest way to keep track of solar panel efficiency is to use peak sun hours. A peak sun hour is equal to the standard solar irradiance and helps you gauge how much power a solar system can generate.
You can use this guide to calculate peak sun hours. If your area receives an average of 7 peak sunlight hours, you can calculate how many solar panels are needed to power a 450WH / 5000 BTU air conditioner for 8 hours.
450 watts x 8 = 3600
3600 / 7 peak sun hours = 514
You need a solar system that produces at least 514 watts an hour. Round this off to 600 watts to make up for weather fluctuations and system losses.
If your air conditioner uses 500 watts instead of 450, and you have less/more peak sun hours, use the same formula but replace them with your figures.
How Many Batteries to Run a 5000 BTU AC?
The battery bank size depends on the power consumption of your AC. You also have to make allowances for the depth of discharge (DOD). if you are using an inverter,make sure the battery is fully charged.
You can use solar panels to charge batteries with lithium, AGM or lead acid batteries. Lithium is ideal because they have a longer DOD, 80% compared to 50% for lead acid.
For a detailed comparison between these batteries, check this guide AGM vs. lithium vs. gel batteries .
The formula is:
Watt consumption / depth of discharge = battery watt size required
Battery capacity is measured in amp hours (ah). To convert to watts:
Watts required / battery voltage
Most lithium batteries have a DOD of 80%. If your 5000 BTU AC consumes 3200 watts a day:
3200 / .8 = 4000
To find the amp hour equivalent, multiply by the voltage. Batteries are usually 12 or 24 volts. Let us use 12 volts here.
4000 / 12 = 333.3
A 5000 BTU AC running at 3200 watts a day needs a 333 ah battery capacity. Four 100ah 12V Ampere Time batteries will be sufficient.
What Charge Controller Size Do You Need?
Charge controllers ensure that your batteries receive the right amount of charge from solar panels. They provide protection from overheating and overcharging.
To find out the right charge controller size:
Total watts produced by solar panels / battery bank voltage = charge controller amp required
In this example you have a 600W solar system and a 24V battery bank running your air conditioner. A 30A MPPT charge controller is ideal.
600 watts / 24 volts = 25 amps
Note that in our calculations, you will need 4 x 100ah 12V batteries. However you can connect these in a series to increase the voltage to 24 volts. You should also make sure the battery to charge controller wire size is correct.
Your charge controller must be at least 25 amps. Round that off to 30A and you have the right device. An MPPT controller costs more than PWM but is more efficient.
If you are running a small solar system or on a budget, a PWM controller will do. But to get the maximum performance from your solar system, an MPPT is required.
What Inverter Size for a 5000 BTU AC?
A 1500 watt pure sine wave inverter is the minimum required for a 5000 BTU AC using 3000 watts a day. If you are going to load more appliances or devices, a 2000W or larger inverter will be needed.
Inverter power is measured in two ways, surge and continuous power. Continuous power refers to how much the inverter can run continuously. A 1500 watt inverter can run a load up to 1500 watts continuously.
While this is technically possible, it is best not to run inverters at full load, at most around 85-90%. This is due to these systems not being 100% efficient.
Inverters are also rated by efficiency, which tells you how much watts it can actually run. Due to system losses, a 1500W inverter will probably only load 1400 watts continuously if it is 95% efficient.
Surge power indicates how much output an inverter can load for a short period. Typically this is double the continuous power.
A 1500W inverter can handle up to 3000W power surge for a brief time. Air conditioners and refrigerators typically need a lot of power to start up.
A 5000 BTU AC running at 500W an hour usually needs 1500-2000 watts. Some units might actually need 3000 watts. Either way, a 1500W inverter with 3000W surge power can handle it.
Even if your AC only uses 2000W at startup, you can use the remaining 1000W surge power to run other appliances.