Inverter Efficiency: Pure Sine VS Modified?

[Steve Spence]

pure sine is less efficient than modified square wave. however, your laptop
is perfectly happy on modified square .....
--
Steve Spence
www.green-trust.org

I currently have an inexpensive "Eliminator" 400W (peak) inverter, its

output

is a modified sine wave, it draws 0.2 amps with no load on it, and has an
efficiency of 90% according to its manual. I am concerned about using the
output for certain things (this laptop for instance), am thinking a pure

sine

inverter is the wiser choice, but the models I've come across so far all

draw

too much power (0.5 amps for 300W continuous). Is this a characteristic of
pure sine inverters, or am I just looking at the wrong stuff? How

important

is a pure sine wave?
--
Slackware9.0, IBM Thinkpad560 <P100, 40MRAM>

[Simon]

OK, here I go again.

Modified sine wave does not exist. No one generates a pure sine wave and
then modifies it. They generate a bastardized square wve and try and filter
it a bit. Marketing calls it a modified sine wave.

You asked about efficiency.

Pure sine wave inverters are typically less efficient than modified square
wave inverters. That does not mean much except in very small systems.

Overall system efficiency from the panels to the appliance group as a whole
is more relevant.

While MSW inverters are more efficient than sine wave ones, that does not
mean that the appliances operate as efficiently on an MSW system than on a
pure sine wave system. Fridges may have to run longer to provide the cooling
effect, deep freezes similarly, and using MSW you may find the system needs
more battery power and more PV power to make up for the appliance
inefficiency. Where does this inefficiency go? In heat, and noise. Noise as
in hum on stereos and CF or other lights. Also, many power supplies will
fail under MSW, for example the power supplies in motion detectors on my
garage!

Most countries have moved away from MSW and use pure sine wave, we are a
little behind.

In essence, there is little point in having a 100% efficient MSW inverter
when the appliance runs at 50%, when a pure sine wave inverter may be 90%
efficient and the appliance may be 90% efficient. Figures exagerated of
course.

Yer pays er money yer gets yer choice.

Simon

www.geocities.com/s_wheaton for my solar system using 4 sine wave
inverters (one is always a backup) and one MSW inverter for the well pump.
And 3 kw of panels and two independant battery banks, one is T105s, the
other the Rolls 4KS21PS

[Antonio Vela]

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Antonio Vela Vico
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