Will a 3000 Watt Inverter Run a 5000 BTU AC?

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Air conditioning units are energy intensive appliances, so if you are running a solar system, the components must be up to par. So if you have a 3000 watt inverter, is it enough to power a 5000 BTU AC? And for how long?

A 5000 BTU AC needs 1000 to 1500 watts to start up and 500 to 600 watts to run continuously, so a 3000 watt inverter is sufficient. The inverter can run the AC for up to 6 hours a day with a 100ah battery.

How Many Watts Does a 5000 BTU AC Use?

BTU stands for British Thermal Unit and determines how much heat is moved from the interior to the outside. It is the standard measurement for AC units.

One BTU is about 293 watts, so 5000 BTUs is 1500 watts. However, an AC with a high EER rating will consume less than that when it runs compared to when it starts.

AC system power consumption often states the running watts, which is different from its starting or surge watts. In most cases, the surge is double or three times the running watts.

A 5000 BTU AC might use 500 to 600 watts to run, but it might need 1000 or 1500 watts to start the motor. Either way a 3000 watt inverter should have no problem handling this.

The surge watts is only going to take a second or less. It is not as if the AC is going to use all 1500 watts from the inverter power source. Once the AC is running, it will consume 500 to 600 watts depending on the settings you chose.

Inverters are also rated according to running watt capacity. So this means a 3000 watt inverter has a 6000 watt surge watt limit. So even if a 5000 BTU needs 600 watts to run and 2000 watts to start, it will not be a problem.

Of course there are different types of air conditioners and how you set them affects the power consumption. The weather also plays a factor. The hotter it is, the harder the motor has to work to cool the air.

The power consumption will change depending on the weather and configuration settings. Power consumption given for AC units and other appliances are for average usage. There will be times your usage will be higher or lower so you have to account for that.

AC Watts and Inverter Size Guide

The older the AC, the more watts it consumes. Modern air conditioners are more efficient so it is more ideal for solar inverters. If you are going to run large appliances on solar power, invest in energy efficient products.

Please keep in mind there are different types of AC systems and settings. Two ACs listed at 5000 BTUs might use different levels of power depending on the settings used.

To find out how many watts an air conditioner uses, check the model nameplate or its product manual. If the power draw is in amps, multiply amps by volts. You can do the same with a refrigerator.

For comparison, here is the power consumption of various AC units and what inverter size you need.

AC BTURunning WattsStarting Watts Suggested Inverter Size
5000 400 to 62012001500
6000 500 to 75015002000
80001000 to 200020002500
10000830 to 125025003000
12000 1000 to 150030003500
150001250 to 187535004000
180001500 to 225040005000

The figures given here are estimates. You should always check the operating manual or manufacturer to get the specific power requirements.

The guide makes it easy to see what inverter size you need. If you have a 6000 BTU air conditioning unit, the Ampeak 2000W Power Inverter should be able to run it.

The table assumes the starting watts is twice the running watts. If it is three times you will need a bigger inverter.

Air conditioning power requirements can vary depending on the season. Obviously it is going to need more watts during the summer as you will be running it at higher settings.

How Long Will a 3000 Watt Inverter Run a 5000 BTU AC?

The runtime depends on the inverter power source. No matter what the inverter size is, it is only as good as its power source.

If your solar system is on the grid, you can run the AC as long as there is power. The inverter can draw energy from your solar array or the power company, so the AC can run continuously.

An AC running on a grid tied inverter will only stop if the main power gets cut off. In the event of a power outage, you won’t be able to run the AC even on solar since it gets shut down for safety reasons.

Most homes with solar power are connected to the grid. In that case you do not need any batteries to operate the AC or any appliance. There is no runtime limit, but this is not the case if your home is off the grid.

How Many Batteries Do I Need to Run a 5000 BTU AC?

An off grid system needs a generator or a battery bank to power an AC. It is possible to run an air conditioner with solar panels, but without batteries you will not be able to use the unit at night.

A 5000 BTU AC draws 5 to 7 amps an hour. A 3000 watt inverter and a 100ah battery bank can run the AC for 5 to 6 hours.

If the AC pulls 7 amps an hour, that would be 42 amps for 6 hours. The closest available battery size is 50ah.

You may use a 50ah battery, but it will be fully discharged. Deep cycle batteries are only meant to be used at 50% capacity, so you need at least 100ah.

With a 100ah battery you can keep the AC going for 6 hours without discharging the battery below the 50% level.

The larger the battery bank, the longer the AC can run. With a 200ah battery bank the unit is good for 12 to 14 hours assuming it draws 7 amps an hour. We prefer the Ampere Time Lithium LiFePO4 battery because it has a long life cycle and needs no maintenance.

If you do not want to deal with the 50% depth discharge rate, get a lithium battery. You will be paying a premium but you do get 90% to 100% full discharge.

For the set up to work, the inverter and battery bank must not have any other load. If you load a toaster on the inverter it will divert the power and there will be less power available for the AC.

No matter what the battery type is, it will lose power the more amps are drawn. If you have a 100ah battery and the AC draws 5 amps an hour, the system can run for 20 hours before it is fully discharged. But if it draws 7 to 10 amps it might last for less than 10 hours.

Reminders For Using an Inverter with a 5000 BTU AC

  • Check the watts and amp consumption of the AC before you buy it.
  • Note how long you intend to run the air conditioner. This will give you an idea of how many amps and watts it will use.
  • Once you have the power requirements, check if your inverter size is sufficient. A 3000 watt inverter is enough provided you won’t be loading the system with other appliances.
  • You can save power by using the lowest settings on the AC. Of course there will be times when you will need to use more power.
  • When measuring battery bank size, consider how much load it will carry. Make sure there is enough for the AC to run for the period you want.
  • Check the warranty for the inverter and the AC. The longer and more comprehensive the warranties, the better.
  • Do not run the inverter to its limit, in this case 3000 watts. Doing that will push the system to the limit which is not good for the long term. The same thing for the batteries, as there should always be some power left in reserve.


There are several types of 5000 BTU AC systems, so performance will differ depending on the manufacturer. The same thing can be said for inverters, so check the specifications to get a better idea of how it will perform on your system.