# Solar power systems - inverters

So far, we have generated electricity using a solar cell, passed it thorough a charge controller which regulates the voltage and then stored it in a battery set. We now need to convert the 12V DC electricity to useable 120V AC.

This the job of an inverter also know as a DC to AC convertor. Essentially, it does the opposite of what a battery charger does. The most common battery voltage inputs for inverters are 12, 24, and 48 volts DC - a few models also available in other voltages.

An inverter takes the DC input and runs it into a pair (or more) of power switching transistors. By rapidly turning these transistors on and off, and feeding opposite sides of a transformer, it makes the transformer think it is getting AC. The transformer changes this alternating DC into AC at the output. Depending on the quality and complexity of the inverter, it may put out a square wave, a quasi-sine (sometimes called modified sine) wave, or a true sine wave.

Inverters are rated in continuous wattage and surge watts. Continuous watts is the total watts the inverter can support indefinitely. So a 4000 watt inverter can power up to 4000 watts continuously. Surge watts is how much power the inverter can support for a very brief period, usually momentary. So a 4000 watt inverter rated at 7000 surge watts can handle up to 7000 watts momentarily while starting such loads as motors - which usually require more than normal power to get started.

Inverters can be used without a solar system for application such as motor homes, camping and trucks where 12V and 24V are readily available but 120V is required.