Solar inverters produce one of two different types of wave output:
* Modified Square Wave (Modified Sine Wave)
* Pure Sine Wave (True Sine Wave)
Modified Sine Wave Inverters
Modified Sine Wave solar inverters are better in typical solar applications when electric motors are not involved. They are not quite as efficient as pure sine wave inverters, but you'll find that they are much more affordable. Unlike pure sine wave inverters, modified sine wave intverters produce a stepped waveform, which isn't really a sine wave at all.
Because the current is not alternating perfectly, the stepped waveform of the modified sine wave inverter causes the inverter to generate an irritating buzz. Take this into careful consideration when purchasing an inverter.
Pure Sine Wave Inverters
pure sine wave solar inverters are very efficient and have a very accurate waveform to the pure sine wave. pure sine wave inverters are a little more pricey than modified sine wave inverters because of the reduced noise and their strong compatibility with certain devices, such as electric motors. This is the better option if you value silence, or want optimal performance from electric motors, such as those found in an electric water pump.
Why we only use the pure sine wave inverters on TV,icebox,not modified inverters
Fourier Analysis states that ANY given signal (Square Wave, Impulse...etc) in time can be given as a SUM of a certain number of Sine Waves, the number of sine waves can be EXTREMELY large depending on the type of the signal itself. That is why it is called Fourier Series.
Now, those Sine waves consist of:
1- Fundamnetal Componenet (at desired frequency)
2- Harmonics (undesired frequencies).
So, signal = fundamental component + harmonics
For a Pure Sine Wave Inverter, basically you end up with one Sine wave signal at the desired frequency (the fundamental component ONLY), this means that all your energy is concentrated in this particualr frequency
For Modified Sine/Square wave, you end up with a Sine Wave signal at the desired frequency (Fundamental Component) as well as other sine waves with different frequencies (Harmonics), this means that energy is distributed over a frequency spectrum and you are losing some energy in the undesired frequencies (harmonics). Those frequencies are normally ignored by the power consumer (TV...etc)
Suppose that your TV works at 50 Hz freq
With a Pure Sine inverter, the output is a Sine Wave @ 50Hz
With a Modified Sine, the output is a Sine Wave @ 50Hz, as well as some other Sine Waves @ 75Hz, 125Hz...etc, your TV will pick up the 50Hz signal, but of course you lose some energy in the unwanted 75,125Hz...etc
So, Pure Sine is the most effecient----> MOST EXPENSIVE.
Modified Sine is more popular because it is more cost effective, and it should work with most of the applications, unless the application is very sensitive to frequency, this is something you can check with the manufacturer of the TV...etc