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A power inverter, or inverter, is an electronic device or circuitry that changes direct current (DC) to alternating current (AC).

Why an inverter is needed

The utility grid supplies you with alternating current (AC) electricity. AC is the standard form of electricity for anything that “plugs in” to the utility power. Direct current (DC) electricity flows in a single direction. Batteries provide DC electricity. AC alternates its direction many times per second. AC is used for grid service because it is more practical for long distance transmission.

An inverter converts DC to AC, and also changes the voltage. In other words, it is a power adapter. It allows a battery-based system to run conventional AC appliances directly or through conventional home wiring. There are ways to use DC directly, but for a modern lifestyle, you will need an inverter for the vast majority, if not all of your loads (in electrical terms, “loads” are devices that use electrical energy).

Power capacity – “Continuous” and “Surge”

How much load can an inverter handle? Its power output is rated in Watts. Read details under “Characteristics of Sinusoidal AC Power” on page 7. There are two levels of power rating -a continuous rating and a surge rating. Continuous means the amount of power the inverter can handle for an indefinite period of hours. When an inverter is rated at a certain number of Watts, that number generally refers to its continuous rating. The “surge power” indicates the power to handle instantaneous overload of a few seconds to provide the higher power required to start certain type of devices and appliances.