Battery Equivalents and Replacements

Solar Powered Air Conditioner: How Many Solar Panels To Run an AC Unit

Running an air conditioner unit during blackouts, in emergencies, when camping, and in other similar situations when the mains power is not available, requires solar panels to collect the energy, a battery pack to store the energy, and some form of power inverter that will convert chemical energy in batteries into electricity suitable for powering AC units and hopefully few other smaller loads like lights, TV and similar.

As heating and cooling devices, modern air conditioners are very effective and they require less energy than air conditioners just a few years ago. Nonetheless, it is vital to know the exact power and energy requirements of your AC unit.

Published: February 2, 2022.

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window ac unit

Air Conditioner Power Requirements

Air conditioners come in various types, sizes, heating/cooling power, energy classes, and similar.

The best course of action to determine the actual power requirements of your AC unit is to check the documentation that came with the unit. Or check it online.

If that is for some reason not an option, here is the list of common air conditioner units and their power requirements, given in Running and Starting Watts:

- RV Air Conditioner 7.000 BTU: 900 Running Watts, 1700 Starting Watts,

- RV Air Conditioner 10.000 BTU: 1200 Running Watts, 2000 Starting Watts,

- RV Air Conditioner 13.500 BTU: 1600 Running Watts, 2500 Starting Watts,

- RV Air Conditioner 15.000 BTU: 1700 Running Watts, 2700 Starting Watts,

- Window Air Conditioner 5.000 BTU: 600 Running Watts, 900 Starting Watts,

- Window Air Conditioner 10.000 BTU: 1200 Running Watts, 1800 Starting Watts,

- Window Air Conditioner 12.000 BTU: 1500 Running Watts, 2300 Starting Watts,

- Window Air Conditioner 15.000 BTU: 1900 Running Watts, 2900 Starting Watts.

Note: as the technology goes forward, air conditioners become more and more energy-efficient.

As an example, we will do calculations for 10.000 BTU air conditioner requiring 1200 Running Watts and 2000 Starting Watts - actual power and energy requirements for AC units can be lowered by decreasing the fan speed and cooling/heating effect, but we will assume that the AC unit is working at full power.

Air Conditioner Energy Requirements

Now that we know power requirements, we can calculate energy requirements needed to power 1200/2000W AC unit for a certain period of time - required energy is given in the following chart:

Hours 1h 3h 5h 8h
Energy 1200 Wh 3600 Wh 6000 Wh 9600 Wh

So, if we want to power 1200/2000W AC unit for, for example, 3 hours at full power, that AC unit will consume 3600 Wh of energy.

Now that we know power and energy requirements, it is important to decide whether we want to run an AC unit during daylight or we have the need to power it during night hours as well.

Running Air Conditioner During Daylight Only

When running AC units and other loads during the daylight, one needs:

- solar panels of enough power to collect the sunlight and convert it into electricity,

- solar battery charge controller to convert the electricity from solar panels into electricity suitable for charging the deep cycle battery (or battery pack),

- power inverter that will convert energy from the battery and solar charger controller into electricity suitable for powering external loads, in this case, 1200W/2000W AC unit.

Note: many modern solar battery charge controllers are actually multifunction devices that also come with a power inverter built-in, simplifying the setup.

In this example, a deep cycle battery is used ONLY for providing power for starting events and not for storing energy and releasing it later, during the night.

Few real-life assumptions:

- solar battery charge controller/power inverter efficiency is 80%,

- solar panel energy efficiency is 50%,

- there are 8 hours of daylight.

So, in order to run 1200W AC unit continuously, one needs:

Psol-el = PAC / CCeff = 1200W / 0.8 = 1500W

Note: Psol-el is solar panels output power (or input power in solar charge controller), PAC is the power of AC unit, CCeff is charge controller efficiency.

So, in order to power such AC unit, solar panels need to provide 1500W continuously. Since solar panels don't operate in ideal conditions, one needs to install 3000W of solar panels (we assumed solar panel energy efficiency of 50%) to power a 1200W AC unit via an 80% energy efficient charge controller/power inverter.

Running Air Conditioner During Day or Night

When running AC units and other loads during both day and night, one needs:

- solar panels of enough power to collect the sunlight and convert it into electricity,

- solar battery charge controller to convert the electricity from solar panels into electricity suitable for charging the deep cycle battery (or battery pack),

- large deep cycle battery or battery pack,

- power inverter that will convert energy from the battery and solar charger controller into electricity suitable for powering external loads, in this case, 1200W/2000W AC unit.

Also, we will also assume:

- solar battery charge controller/power inverter efficiency is 80%,

- solar panel energy efficiency is 50%,

- there are 8 hours of daylight.

In order to run a 1200W AC unit for three hours, one needs to provide 3600Wh of energy to the AC unit. Since energy conversion is not ideal, the battery must be able to store:

EBat = EAC / CCeff = 3600 Wh / 0.8 = 4500 Wh

Note: actual energy efficiency, in this case, is usually lower than in the first case, but not by much. So we again used 80% energy efficiency for the solar charge controller.

In order to collect 4500 Wh of energy during 8 hours of daylight, 50% energy efficient solar panels require:

P = Ebat / (T * SPeff) = 4500 Wh / (8h * 0.5) = 1125 W

of installed power.

But, one also must have a deep cycle battery capable of storing 4500Wh of energy - since we didn't calculate energy losses in the battery, it is highly recommended to use a high-quality lithium battery (or battery pack) to store such an amount of energy.

ampere time 12v 300ah

One of the recommended deep cycle lithium batteries is Ampere Time 12V 300Ah LiFePO4 Battery (Amazon link, link opens in the new window), featuring nominal voltage of 12V, capacity of 300Ah, maximum continuous discharge current of 200 Amps, maximum surge current of 400 Amps, and supports battery packs up to 4S4P.

Just two of these batteries can store 7200+ Wh of energy and provide up to 4800W continuously and 9600W for 5 seconds - not bad for a battery pack weighing just 126 pounds (~57 kg).

Note: just one 12V 400Ah lithium battery can store 4800+ Wh of energy, which is more than the required 4500Wh (in this example). It is up to the user to decide which setup best fits one's needs.

Can a Solar Generator Run an Air Conditioner

Solar generators (power stations) come in various sizes, featuring different power outlets, output power, etc.

One of the most popular high-end solar generators is Bluetti AC200P Portable Power Station/Solar Generator featuring 2000W continuous watts, 4800 surge watts, 2000Wh internal battery, 85% energy efficiency, 700W max. solar input, etc.

Without solar panels, Bluetti AC200P can provide 1200W for ~1h and 20-25 minutes. Also, even if a full 700W of solar panels is attached to the Bluetti AC200P, it is not enough to both charge the unit and power the 1200W AC unit (Bluetti AC200P supports pass-through charging).

But, if such AC unit is throttled down from 1200W to 500W, using Bluetti AC200P and 5 (five) Bluetti SP200W (200W) solar panels, one can do one of the following:

- fully recharge 2000Wh battery in 3.5-4 hours, even somewhat faster in favorable weather conditions,

- power 500W external load without discharging the built-in battery.

And when the sun is gone, the fully charged internal battery can power a 500W load for an additional ~3h and 20-25 minutes.

bluetti ac200p

Are there larger units than Bluetti AC200P that can, for example, accept more solar panels? Yes, there are, but they also tend to cost more, much more.

Also, the 1200W/2000W AC unit in our example is just that - an example.

For the most up-to-date offers and prices, feel free to check the Bluetti AC200P Portable Power Station manufacturer page (affiliate link, opens in the new window), or Bluetti AC200P Solar Generator Amazon link (link opens in the new window).


Few Final Words

window ac unit mEverybody has different power and energy requirements - thus, the equipment should be dimensioned according to personal needs and requirements.

Having some extra power and energy is a good safety measure, just be sure not to go too far - adding something here and there quickly increases the complexity and in the end the price of the system.

So, can You power an air conditioning unit using solar panels? Yes, You can, just be aware of the limitations of the technologies involved.

Amazon Search:

- Portable Power Station

- Solar Panel

- Portable Power Station Solar Panel Kit

Note: Amazon links open in the new windows, feel free to check them for the most up-to-date offers and prices.