An inverter is an electronic device which takes incoming low voltage DC (Direct Current) power from a battery such as in your car, RV, boat, trailer or solar and wind system and converts it to AC (Alternating Current) to run most household 120 Volt appliances.

Low voltage DC power is converted through an oscillator to an equal voltage of AC power. The low voltage AC power is then set at a frequency of 60 Hertz. That means the polarity (positive and negative) is switched back and forth at 60 cycles per second creating either the 'modified square wave' or 'pure sine wave' depending on which type you buy. The transformer will step up that low voltage AC to the utility standard 120 or 240 volts. Modified Square Wave inverters are also sometimes called Modified Sine Wave Inverters. Backup and portable generators produce a wave form called 'Sinusoidal'. This wave form is equivalent to the utility or grid generated electricity.

Peak Watts or Surge ratings?
Some appliances can draw a split second start up load of 3 to 5 times it's rated amperage and wattage. This start up load is also called a power spike or 'Surge'. The 'Peak Surge' rating of an inverter is factored to provide surge protection for such appliance and motor load start up surges. The 'Peak Surge' or 'Peak Watts' rating is usually double the continuous inverter AC wattage output rating but usually only for 5 minutes maximum. If your looking to power any electrical motor or inductive loads, just make sure you factor that surge in the inverter you choose and lean towards a true transformer type inverter like the Magnum, Outback or Tripp lite brands.

Inverters using a Square or Modified Sine Wave can operate a large portion of modern electrical appliances with no problem. However, the fast switching edges or 'square' wave form can produce a buzzing or humming noise in some items such as inexpensive stereos and TV's, ceiling fans and other audio equipment. Modified Square Wave Inverters are electrically efficient and relatively inexpensive. Pure or True Sine Wave Inverters produce 'cleaner' power and a smoother sine wave form but generally cost twice as much or more than Modified Square Wave. Inverters for Grid Dependant or Interactive Renewable Energy Systems must be Pure Sine Wave to be compatible with the utility or grid generated electricity.