What they are

An inverter is a device that takes power from batteries and turns it into power that can be used by office or household appliances.  These systems are quiet, less powerful supplements to a generator or publicly-provided power.

If you are running a generator or are in an area where publicly provided power is unreliable, it is a good idea to have an inverter and batteries to supplement the main power system.

How they work

When the generator or public power is on, in addition to providing power to your appliances, it charges a set of batteries.  Then, when the main power source goes off (either because public power went out or because you turned off the generator), you can turn on the inverter to start using the power that was stored in the batteries.

When to use them

You generally use an inverter when you can’t or don’t want to run a generator, for instance, when the generator needs a break (over the lunch hour), or when you are just not going to be drawing a lot of power but you still need the basics, like lights (overnight).  You use an inverter to power the basics – lights, ceiling fans, computers, and the internet.

You should not use inverter power to run heating and cooling appliances like air conditioning units, water heaters, or electric room heaters or devices with motors (like a treadmill).

Sizing an Inverter

Just as with a generator, you will decide about an inverter based on the amount of power you want it to provide.  You will also factor in how long you want the power to last (2 hrs?  12 hrs?).

You will also have to think about where you want to have outlets.  Generally inverters power separate, parallel wiring systems.  When the main power is on you use one set of wires and outlets, and when the inverter is on you use a different one.

Installing an Inverter

Call a professional to help you size and install an inverter.    Generally inverter systems require separate wiring and this will have to be installed.  The companies that install generators can usually also install inverters.  Look to solar energy companies as well as solar energy set-ups require inverters.