Inverters
An inverter is used to convert DC electricity (usually from batteries) to 240 volt AC power. There
are two broad categories of inverters recommended for power supply applications, modified
squarewave and sinewave. The sinewave inverters also can be broken down into two further
categories, stand-alone (usually powered from a battery) and grid interactive (for feeding into
the national electricity grid)
Grid-Interactive Inverters
not only convert the DC electricity from solar modules (or any other suitable source such as fuel
cells, turbines etc) into pure sinewave grid quality power, they have to actually monitor the grid
waveform and duplicate it exactly. They must also disconnect from the electricity grid if it fails
for any reason (such as being switched off for maintenance). Any electricity generated not used
in the home is exported through a special meter into the main electricity supply. Some of these
inverters have a feature called "Maximum Power Point Tracking" or MPPT, where the inverter
will determine the maximum input voltage and current values to get the maximum power
possible out of your investment. Some Grid-interactive inverters have battery backup facilities,
which can supply power to your requirements during blackouts, as well as "sell' electricity to the
grid. Please call or email us with your requirements.
Modified square wave inverters
(also called modified sine wave and quasi sinewave) produce a step-shaped output, which will
operate most AC loads, but may upset equipment with timing functions such as TVs, VCRs,
computers and induction motors. Recommended for: most applications, including power tools,
general lighting etc
Not recommended for: electronic flow control pumps, and any appliance with older
switch-mode power supplies or microwave ovens as they both require the sinewave peak to
operate efficiently.
We do NOT recommend the use of cheap square-wave inverters in any application, as these
usually have very bad output waveforms, and the high voltage spikes on the output could
damage your appliance. We have seen some of these "hobby inverters" trip surge guard
protectors with nothing plugged in! Also make sure that the inverter you are looking at
purchasing is fully isolated and M.E.N. compliant if using it in a fixed installation. All inverters
listed in our catalogue are compliant. These requirements are covered in the
Australian Standards
AS3000, and are required by law. Almost all of the cheap inverters available do NOT comply
with these standards and are suitable for mobile applications only.
Pure Sinewave inverters
produce a smooth output similar (sometimes better) to that from the mains grid. The power
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Inverters
output is much higher in quality than modified square wave inverters and has a greater voltage
stability than the grid. However, they are also the more expensive of the two types, due to the
complexity of re-producing the sinewave from a pure DC source.
Sinewave inverters are quickly becoming the industry standard, are readily available and are
not much more expensive than modified square-wave inverters. Again, there are many cheap
sinewave inverters that do not comply with AS3000 for fixed installations, be aware of this if
purchasing an inverter for a particular application.
Inverter/chargers
combine an inverter (either modified or pure sinewave) with a battery charger. These can be
either simple or complex devices used for many things, such as a simple back-up power supply,
an automatic battery charger and change-over to the grid in a mobile home, back-up generator
charging right through to complex load-sharing systems. The end use will determine the actual
inverter/charger that is used. Please call or email us if you have a special requirement.
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