Is Modified Sine Wave OK For Computers?

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Another way to phrase this question is “do computers really need pure sine wave?” There is a lot of debate which inverter type is best suited for computers, so which one should you use? Is a pure sine wave worth the extra cost?

Majority of desktop and laptop computers will run fine on modified sine wave inverters without experiencing any problems. Older computers may produce a humming sound, but a modern computer is not going to have no issues.

Do You Need an Inverter For Computers?

If your laptop works on DC power – and most do – an inverter is not required. You can just plug the laptop into a solar power station or a portable solar charger and it will recharge.

Solar panels produce direct current (DC) power, so if you can plug your computer into the solar system it will run. A better option is to let the solar panel charge your battery bank and use the batteries to power your computer.

Solar panel power output depends on sunlight, so you will get more consistent power from a battery bank. As long as the battery has sufficient charge and is compatible with your inverter, the laptop will run smoothly.

If you are camping and use a typical laptop, an inverter is not needed. You can run it on batteries and use a portable solar charger or generator as necessary.

But if you have a solar system at home, your computer will have to run through an inverter. In this case you need to understand how inverters work and what appliances – besides computers – you can use with a modified and pure sine wave.

Tips For Running a Computer on an Inverter

  • Make sure the computer is compatible with your inverter. While most will run fine, it is best to be sure. If the manufacturer does not say anything about inverters, assume the computer works only with pure sine wave.
  • Interference. Some computer monitors may display lines or generate a humming noise when running on modified sine wave. This is common and not a sign of damage.
  • Power supply concerns. The power brick on some computers do not work well with modified sine wave. You won’t notice any immediate effect, but over time it might deteriorate.
  • Peripherals. Electronics equipped with thyristors do not work well with modified sine wave. Some laser printers have this component so keep that in mind when setting up your system.

One of the arguments made in favor of pure sine is they are designed specifically for delicate electronics. If sewing machines with micro processors need pure sine, what about laptops and desktops?

While some laptop power bricks are optimized for pure sine wave, most computers can handle modified sine wave inverters. The fact is modified sine are the most widely used inverters and laptops all over the world run on them without problems.

The one thing you need to consider is the inverter size. It has to be large enough to handle the computer so it does not overload. Most laptops use 100 to 250 watts while desktops range from 200 to 400 watts. Gaming systems can consume up to 800 watts or more.

It does not matter how much power your computer uses as long as the inverter can supply it. Unlike a refrigerator or AC unit, computers do not have any surge watt requirements. Even if you add a printer and speakers, an inverter should have no trouble running a computer.

The bottom line is if the manufacturer says it is all right to use modified sine, go ahead. If they recommend pure sine or does not say anything about inverters, use pure sine wave.

Difference Between Pure and Modified Sine Wave Inverters

There are many differences between pure and modified sine wave , but the most important is pure sine resembles an actual sine wave, whereas the modified ones abruptly change polarities. In simple terms, pure sine is more efficient and also more expensive. Modified sine wave is simpler and costs less. But how does this translate to actual appliances, devices and motors?

Devices That Can Run on Modified Sine

If the device is not a medical apparatus and does not use an AC motor, it should be compatible with a modified sine wave inverter. Most laptops use a rectifier to convert AC to DC so there should be no problems with modified sine.

But as pointed out earlier, the power brick in some laptops are sensitive and will benefit from pure sine wave. There is a reason why some advanced computers recommend pure sine wave and if yours does you should follow it.

Devices That May Not Run on Modified Sine

Appliances that use AC motors like compressors, refrigerators and microwaves will perform better on pure sine wave. Some of these appliances will not even run on modified sine wave inverters, and if they do, performance will be reduced.

Some AC motors will run on modified sine, but there is a risk of heat buildup that could damage the inverter, appliance or both. This may or may not happen, so check the appliance owner’s manual for what inverter it works with.

Medical equipment like CPAP and oxygen concentrators work best with pure sine wave. These devices have sensitive components that might get damaged if run on modified sine wave.

Radios can run on modified sine wave, but there might be interference and distort the signal. You can compare this to the lines that appear on some computer monitors when running on modified sine.

Any light fixture with electronic ballasts may or may not work with modified sine. Most other solar powered appliances however should be compatible with modified sine. Most power tools are going to work fine too.

Benefits of Pure Sine Wave Inverters

All right, so your computer and other appliances will probably be all right with a modified sine wave inverter. But why do most manufacturers recommend pure sine wave?

What you are paying the extra price for is efficiency and superior performance. Sure your laptop will be okay on a modified sine, but pure sine wave generates clean, low distortion current similar to what you get with grid supplied power.

Computers designed for pure sine wave will crash less compared to running them on modified sine. Some computers with advanced chipsets benefit from pure sine wave and it will reduce glitches and freezes. Again it comes down to the system design whether it is compatible with modified sine or not.

The benefit is not just limited to desktops and laptops but peripherals too. Printers designed for pure sine wave will not print properly on modified sine. You can connect it but when you print something the text and image may come out garbled.

Some magneto optical hard disks are optimized for pure sine wave. It may still run on modified sine, but there is the risk of adverse long term effects. The disk may be running now but its lifespan might be shortened.

The following are some devices that run best on pure sine. Most of them except those with AC motors may work on modified sine. But these appliances / devices are not optimized and may encounter problems in the long term.

  • Medical equipment
  • X10 home automation systems
  • Computerized sewing machines
  • Digital radio clocks
  • Computerized pellet stoves
  • Computerized furnaces
  • Some power tools with variable speed control
  • Fluorescent lights equipped with electronic ballasts

Another benefit of pure sine wave inverters is it reduces the sound produced by computers, TVs, video game consoles and audiovisual components. A microwave running on pure sine will also run quietly.

The list of devices above are for general information purposes only. There are many types of digital radio clocks, and some may run better on modified sine wave than others. Use the guide above as a starting point to find out if your device may or may not run on your inverter system.


So the bottom line is most computers should be all right running from a modified pure sine inverter. There might be a few lines on the screen and a slight hum, but you should have no trouble running applications, playing games and web browsing.