Power Inverters | True Sine | Modified Sine

Both types of power inverters come in all sizes, Some with a built in transfer switch. And
some with a built in battery charger or both. Both types of inverter come with AC outlets
mounted right on the front of them or are the hard wire type for conduit connections. Most all of
the smaller inverters come packaged with battery post clamps or a lighter plug for your car.

Starting at around 2000 watts most are hard wired. A 2000 watt inverter at 12 volts would be
pulling about 166 amps. That takes some good connections and large wires. Electric motors and
compressors such as what are in a refrigerator or freezer work best with true sine and do not
play well with modified sine wave. Some times you can hear the sound of the wave form in the
speakers of your computer or your radio. Motors make a humming sound from the flats on the
square wave form of the modified sine wave.

True sine wave AKA Pure sine wave, do not have any of the above problems to worry
with. If it works great in your home it will work great with Pure/True sine wave.

The hair dryer is the biggest power user that I know of at 120 volts. These things will use as
much as 1800 watts of power. That is a full 15 amps which just so happens to be the breaker size
in some older homes. On a 12 volt battery bank it would be about 150 amps (that is more then
most car batteries have in them). Did you know you can weld metal with 60 amps of power and
less?

A hair dryer justifies a 2000 watt power inverter or larger. A microwave uses around 11 amps
power or about 1300 watts. With either of these two items you would need a little extra power for
lighting. You don't want to eat in the dark or blow dry your hair with no lights.

Stackable power inverters are normally found in the larger sizes. Most of the bells and
whistles are found in the 2000 watt range or higher. A built in and programmable battery
charger is a good option in an inverter. If you are using a 24 volt battery bank you don’t
have to spend the extra cash and buy a charger if it is already built into the inverter.
Normal battery chargers you find in a department store are not what you would need to charge a
deep cycle battery. Most will not equalize a wet cell battery or will not switch to GEL or AGM.

Some times an AC transfer switch will be built into the better inverters. This allows for the built in
charger to keep the batteries charged while by-passing the inverter to power your home. But
when the power goes down it auto switches to the inverter and backup power. You will never
even notice it happened unless the inverter is under a heavy load.

An external stand alone transfer switch can be installed with most any inverter. It can be used as
a go between the generator and the inverter. When the generator is started it disconnects the
grid or inverter and charges the batteries and powers the loads. Or if the grid goes down a
transfer switch would switches the load to the inverter and battery backup.

You should always start from the load end when planing what size of a solar power system you
will build. Get the inverters to match the heaviest load with a little extra power. Pick the wave form
type you will require, Modified Sine Wave or True Sine Wave. Will the inverter with a build in
transfer switch will be useful to you or do you need to go with an external switch. Or if a transfer
switch is needed at all. And do you need a built in battery charger?

Inverters are the first item of interest in a solar backup system or just a backup power system.
You should look for inverters that will do what you need them to do and then size the rest of the
system accordingly.

You are the only one that knows what your plans are. So you have to pick the right inverter or
inverters and other components. So take a little time and put together a few numbers before you
buy. Try your best to pick the inverter you will need a year from now, Because once you buy it the
money is spent. If you upgrade after you build and you did not get a stackable inverter you could
have a shelf item.