This DC to AC converter is very simple and contains no more than 12 components. IC CD4047 generates a signal with frequency 50/60Hz, who paraphase exits 10 and 11 is fed to the gates of MOSFET transistors IRFZ44. Transistors alternately commute primary winding of the transformer floor, and appears on the secondary AC voltage of 220 V. Of course, this voltage has a rectangular shape, but the connection of the capacitor C3 220 nF, it is smoothed out to look like a sine wave.
To increase the output power is necessary to use dual-field-effect transistors, and, of course, the battery capable of providing the appropriate current. For example, to get at the output of 240 watts, the battery should give over 20 A. If you use a transformer 24, you can use the battery for 24 V and current consumption in this case is slightly more than 10 A. For the implementation of the scheme will be more suitable transformer with a 9-volt windings, as in transformers with windings at 12 higher losses.