Pure Sine Wave vs. Modified Sine Wave: What's the Difference?

Updated: Oct 17, 2018

Pure Sine Wave Inverter vs Modified Sine Wave Inverter: What's the Difference?


The inverter is said to be the "heart" of any solar powered generator or any solar energy system. The main purpose of the inverter is to take the DC current that comes from photovoltaic cells or solar panels and convert it to an AC current that can be used by household appliances and devices.


A clean 120 VAC signal is nothing more than a smooth pure sine wave that fluctuates between 120 volts and -120 volts like this:


Pure Sine Wave

This pure sine wave is the most efficient waveform when it comes to electricity and an inverter's job is to replicate this waveform as closely as possible. In early inverter technology, this was achieved by simply stepping the voltages like this:


Modified Sine Wave


This is known as a modified sine wave. Notice the changes in voltage are not smooth like a pure sine wave but they are abrupt. These abrupt "steps" cause harmonic distortion, or "noise," so you will hear an audible buzz in your electrical equipment. Also, a modified waveform is only about 70% as efficient as a pure sine wave and that waste is given off as heat which can also damage components, requiring extra cooling.


Because of the inefficiencies of a modified sine wave inverter, sensitive electronics cannot be powered by a modified sine wave inverter as they could be damaged.


Here is a list of just some of the items that cannot be powered using a modified sine wave inverter:


⦁ Medical equipment

⦁ Laptops

⦁ Battery chargers

⦁ Smart phones

⦁ Digital clock radios

⦁ Variable temperature control devices (heating pads, inductive cook tops, etc)

⦁ Laser printers

⦁ Any new smart device (Washer, dryers, toasters, anything with a microcontroller)

⦁ Photographic strobes

⦁ Variable speed tools


Basically in today's world of rapidly changing technology, there will not be much that can be powered with a modified sine wave inverter as more and more devices are being equipped with embedded microcontrollers. Even devices that can use a modified sine wave like motors will run much hotter and less efficient due to the increased harmonic distortion from the "steps" of the modified sine wave.


For this reason Sol Power Generators highly recomends the use of pure sine wave inverters and only uses high quality pure sine wave inverters in all of it's portable solar powered generators.


How can a consumer know if they are getting a pure sine wave or a modified sine wave inverter? A pure sine wave inverter will always be labeled as one. If you are looking at an inverter and it does not say "pure sine wave," then it is just a modified sine wave inverter. Don't be fooled if it is labeled as a "power inverter" or anything else, it absolutely must be labeled as a "Pure Sine Wave Inverter."


We at Sol Power Generators hope you found this information helpful.

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