Will a 1000 watt inverter run a refrigerator? Yes, if it’s a modern, energy efficient model.
A 1000 watt inverter with a 2000 watt surge capacity should run most modern fridges with a size of around 16 cubic feet.
To be absolutely sure that you buy a correctly sized inverter, particularly if your fridge is very large, you’ll need to know the power consumption of your refrigerator (especially if it’s an older model) and the rated surge capacity of the inverter.
The inverter brand is another factor to consider. When it comes to inverters, there’s plenty of cheap junk out there that doesn’t live up to the advertised power rating or surge rating.
Let’s run through the basics so you can get yourself an inverter that meets your needs.
Understanding Your Refrigerator’s Running Cycle
Refrigerators don’t run constantly. Over an average day (24 hours) the fridge will cycle on and off multiple times.
The total run time, where any significant power is being drawn, works out at about 8 hours a day when all of the on/off cycles are taken into account.
The cycle starts when the temperature in your fridge is higher than the temperature set on the fridge’s thermostat.
The rise in temperature triggers the compressor to start. The compressor is the motor that moves the coolant around your refrigerator.
As with all motors, the initial start up takes a large surge of power for a split second.
Now that the compressor is running, your fridge draw continuous power until the temperature drops back down.
Once everything is nice and chilly again, the compressor will shut down until the next time it’s needed. Power consumption is minimal during this part of the cycle.
After a while the temperature will climb above the set temperature, and the cycle will begin again, starting with another quick power surge as the compressor starts.
If your refrigerator is a frost free model, your fridge will enter a short heating mode several times a day. This heating mode uses a larger amount of power than regular cooling, but it will still be within the rated power consumption of your unit.
Finding Your Refrigerator’s Power Consumption
Before you can figure out what size inverter you need, you need to know how much power your fridge uses. There are several ways you can get this information.
If You Already Own The Fridge You Want To Use With An Inverter
Method 1 – If you already own the fridge you plan to use, look on the appliance for an information label which will list the power consumption. This information should also be listed in your owner’s manual if you still have it.
The label will give you the power consumption in either watts (w) or amps (a).
If the power consumption is listed in watts, you’re good to go and can move on to the next section.
If it’s amps, don’t worry, a simple calculation will convert those amps to watts.
Multiply amps by voltage (which should be listed too) to calculate watts.
In the United States, household voltage is between 115 – 120 volts, and 115 volts is the typical voltage listed on many fridges.
Let’s do the math.
For example, if the amps are listed as 5, then multiply 5 amps by 115 volts to get 575 watts.
In other parts of the world, household voltage will be different. In Europe for example it’s 220 – 240 volts, so use that number in your calculation instead.
Just so you know, 575 watts isn’t the continuous power draw that you would expect your fridge to consume.
This amount of power would typically only be drawn when your fridge is working extra hard, say when it’s high summer and very warm in the house and you’ve just loaded in lots of room temperature items that need cooling down.
Under average running conditions, your fridge will use much less power, but to work out your inverter needs stick with the higher rating.
Method 2 – Another way to find the power consumption of your fridge is to use a meter that measures the wattage for you. The Kill A Watt meter is a good choice, and anyone planning off grid power really should have a way to measure the power consumption of their appliances and devices.
All you need to do is plug the meter into your power outlet, then plug your fridge into the meter. The meter will display how many watts are being used.
Make sure you take a reading when the fridge is actually running, not when it’s in the idle part of its cycle.
If You’re Still Shopping For A Fridge
If you’re still shopping for a fridge, it’s a little harder to find the power consumption information that you need.
It’s a pet peeve of mine that most retailers simply list the annual kilowatt hours (kWh) consumption for an appliance. When you’re working with off grid power, it’s always useful to know actual wattage and amps.
But, if the annual kilowatt hours is all you can find, you can use this rough calculation to figure out an approximate wattage.
I’ll use an example of 365 kWh annual power consumption.
To find the approximate wattage rating, first multiply by 1000 to convert kilowatts into watts.
Then divide that figure by 2920 which is the number of hours in one year that the refrigerator is expected to run.
Why 2920?
As I already explained, a fridge typically runs for a total of 8 hours in a 24 hour period, which is 1/3 of the time.
So if we take the number of hours in one year, which is 8760, and divide by 3, we get 2920.
Here is the math.
365 kWh x 1000 = 365,000 watts.
365,000 / 2920 = 125 watts.
Keep in mind that this will be the power draw while the fridge is purring along without a heavy load of cooling to do. If it’s running hard on a hot day, the power draw will be at least twice that amount, around 250 watts.
Here, I would urge on the side of caution and add some wiggle room because the above calculation can only give just a rough estimate of the watts your fridge will use while it’s running.
I would bump up the estimate to 300 watts.
Now, 300 watts appears to be well within the limits of a 1000 watt inverter, as does the 575 watts from the first example, but a 1000 watt inverter may not run either of them.
Why not?
Because to size your inverter correctly, you’ll also need to factor in the compressor startup power surge.
Refrigerator Continuous Power Draw & Compressor Startup Power Surge
By running through the calculations above, you will already have a rough idea of how many watts your refrigerator will draw while it’s running under a normal or heavy load.
Now, we need to go over the compressor power surge.
The compressor in your fridge is a motor and motors take a much bigger burst of power, for just a second, while they get going.
This power surge is usually around 3 times the rated power.
For a fridge with a power rating of 575 watts, you would need an inverter with a surge capacity of at least 1725 watts to be on the safe side.
For the 300 watt example, your inverter would need to be capable of giving you 900 watts.
If your inverter can’t supply the power needed for the startup surge, your fridge won’t run.
Inverter Power Ratings
When you’re shopping for an inverter, you’ll see two power ratings. The continuous power rating and the surge or peak power rating.
Any decent, 1000 watt inverter should give you a surge capability of 2000 watts which would be more than enough to cover the compressor start up surge in many modern refrigerators.
Which Is better – Pure Sine Wave or Modified Sine Wave ?
A pure sine wave inverter is always the best choice, especially when you want to run appliances with motors . Even though this type costs more, the benefits are well worth the extra money.
Pure sine wave inverters produce a clean output. Clean, in this case means with very little distortion of the output waveform.
With this type of inverter, you’ll get close to or better than the sine wave output from the main electrical grid.
The clean output means that your appliances and devices will have longer product lives, and your motorized appliances will run more efficiently, without making lots of noise, or generating extra heat which will cause your refrigerator to have a shorter lifespan.
Another benefit of pure sine wave inverters is their efficiency, which is generally between 90 – 95%. The efficiency of modified sine wave inverters will come in below 90%, sometimes far below.
For example, if a modified sine wave inverter has an efficiency of 85%, only 85% of the rated power is available to power your equipment. On a 1000 watt inverter, that means you only get to use 850 watts.
With a pure sine wave inverter and 95% efficiency, you’ll have access to 950 watts. And when you’re running power off grid, 100 watts is a big deal. Trust me.
What Size Refrigerator Can A 1000 Watt inverter Run?
A 1000 watt inverter will easily run mini fridges and apartment size fridges. A modern energy efficient fridge with a capacity up to 16 cubic feet should be well within the range of a 1000 watt inverter.
How Long Can An Inverter Run A Refrigerator?
Inverters are designed to provide continuous power to your equipment. As long as you supply DC power to the inverter from your solar panels or battery bank, your inverter will supply AC power to your fridge.
What Size Inverter Do I Need To Run A Full Size Refrigerator?
To be certain that you get the right inverter, you need to know how many watts it will consume. Different styles, brands and models of refrigerator will use varying amounts of power.
A full sized refrigerator could have a freezer on top or on the bottom, or it could be a side by side model.
Each of these types will have different energy needs and that’s without taking the age of the appliance in to account or factoring in the efficiencies offered by better quality brands.
Find out the watts that your unit will consume, then multiply by 3 to cover the compressor power surge. It’s the only way to know for sure.
Will A 1000 Watt Inverter Run A Mini Fridge?
Since mini fridges use very little power due to their compact size, a 1000 watt inverter will easily power your mini fridge.
And because a mini fridge uses such a small amount of power, you’ll be able to power some other devices at the same time.
You could run a laptop, some LED lighting and a fan along with your mini fridge.
Will A 1000 Watt Inverter Run A Freezer?
Yes, as long as both the continuous power and surge power consumption of your freezer falls within the limits discussed above.
Freezers tend to use less power than refrigerators and this is especially true for chest freezers or deep freezes as they’re sometimes called.
Because cold air sinks, these top opening freezers lose very little of their cold air when you open the lid.
Contrast that to a front opening freezer, where the cold air floods out as soon as you open the door.
If you’re shopping for a freezer for off grid use, look for a well insulated chest freezer rated to keep your food frozen without power for 2 to 3 days.
Then if any part of your off grid power set up fails (inverter, charge controller, solar panels, batteries), you won’t lose your food before you can fix the issue.
Ensure Good Airflow To keep Your Inverter Operating properly
Follow this basic advice to keep your inverter in good running order.
When inverters convert DC power to AC power they create heat. The harder your inverter works, the more heat it will produce.
If your inverter gets too hot it will shut off, and regular exposure to excessive heat will shorten its working life.
To prevent overheating issues, leave plenty of room around your inverter, on the top and bottom and both sides. Leaving 12 inches around your inverter is a good guideline to follow.
Never cover your inverter, and make sure that the front of the inverter is unobstructed.
If you purchase an inverter with an integral cooling fan, install your inverter with the fan exhaust at the top.
Because hot air rises, having the fan exhaust on top is the most efficient way to vent the heat.
Tips For Running A Refrigerator On An Inverter
Use the smallest fridge that will meet your needs. The inverter is only one part of running an appliance off grid, and even though your inverter will handle the power load, a large fridge will take a lot of expensive solar power and costly batteries to run.
If you’re running a drinks fridge, and don’t need to keep food fresh, turn your refrigerator off when you don’t need it. There’s no point eating up your battery power to run a drinks fridge overnight. Just remember to turn it back on again in the morning, or for a set and forget option, plug your fridge into a timer.
Try to minimize the number of times you open the fridge to take things out. Every time you open the door, you’ll lose cold air and your fridge will need to draw extra power.
Wrapping Up
A 1000 watt inverter should run most modern, energy efficient refrigerators with a capacity up to 16 cubic feet.
You’ll need to know the power consumption of your fridge to be absolutely sure, and remember to allow for 3 times your fridge’s power rating to cover the compressor’s power surge.
When you’re comparing inverters before you make a purchase, find out the inverter’s efficiency rating, and if your budget allows, choose a pure sine wave inverter for its superior 95% efficiency.
