An inverter is to convert the DC (Direct Current) power from the battery bank or solar panels to AC (Alternating Current) power. This is called modified sine wave, seen in orange in the image below. More advanced modified sine waves make multiple steps, trying to be close to a pure sine wave.
You can see an output of a modified sine wave on an oscilloscope and A Pure Sine wave is shown as below. Other than how the signal looks, what’s the difference between the two outputs?
Modified Sine Wave and Pure Sine Waves on Oscilloscope
Modified sine wave inverter, you can see the square pattern in polarity. The choppy wave indicates that the power quality is not so good , it can negatively affect some delicate or sensitive equipments, like medical equiment,testing machine which require accuracy.
A modified sine wave inverter can be used for simple systems that don’t have any sensitive electronics . Anything resistive load like filament tube tvs, Lights,phone charges heaters are usually fine with modified sine wave. Some electronic products like medical device can not work with modified.
For inductive load such as air conditoner, pump,motor, the modified sine wave inverter can not work for them well. Some modern appliances won’t work well and some even can not workwith the modified sine wave, such as Laser printers, photocopiers, refrigerators, micro waves, compressors, or ac motors. and anything with an electrical component like rectifier . Some device with microprocessor controls,Digital clocks or radios, appliances having speed/microprocessor controls ,Medical equipment like oxygen concentrators can not work with modified sine wave.
Because the total harmonic distortion is higher in modified square wave inverters, motors will run hotter and less efficient and consume more energy by using modified. A Pure sine wave’s output voltage waveform has very low harmonic distortion whereas the modified sine wave could result in interference when powering clocks and audio devices, such as radios which results in a buzzing sound during the operation. What is more,a modified sine wave inverter will often cause buzz from audio devices ect. Pure sine wave inverter can run appliances with ac motors, like washing machine, pump, refrigerator with compressor.
Medical equipments, sensitive electronics, laser pritners, Newer TVs, appliances with electronic timers or digital clocks.
You can use modified sine wave inverter to power your laptop or phone, it will shorten the lifespan of the battery inside.
PURE SINE WAVE INVERTERS ARE MORE PREFERRED
Pure sine wave is as good as the utility power. It is suitable for all kinds of electric device, such as TV, Lights, heater, oven and even inductive loads like washing machine, pump,motors. And the audio system can work well with pure sine wave inverter Pure sine wave inverters are also capable of producing cleaner, smoother, quieter, and more reliable electricity to operate appliances and electronics without interference.
Generally, modified sine wave inverters are much inexpensive than a pure sine wave inverter. There are fewer electronic components inside and less complicated than pure sine wave inverter. It is unable to run continuously like pure sine wave inverter. It can not work up to its full rated power continuously. For long term, it is better to use pure sine wave inverter for the well-being of the ac appliances .Lots of low power car inverters like 300w 150w power inverter are modifies sine wave inverter, it only costs about 30usd. For a pure sine wave inverter for 300w, it can cost 80usd.
For modified sine wave inverter, it has lower efficiency. Motors will use about 20% more power than pure sine wave inverter. it will get hotter and it will consume more power .
Note: Electrical polarity is the direction of current flow in an electrical circuit. There are two types of poles: positive (+) and negative (−).
Pure sine wave inverters are more sophisticated, but as costs continues to drop, it becomes more affordable. Modified sine wave inverters still make a viable option if you have limited, simple appliances to power.
However, if you want to ensure your home appliances and devices run safely, effectively and at the highest efficiency, we recommend you to choose a pure sine wave inverter.