I made and experimental Inverter Printed Circuit Board for my offgrid solarpanels. The project is based on http://bristolwatch.com
inverter by Lewis Loflin.
Schematic and PCB are made with the arduino crowd famous eagle PCB layout program. The brd file, original arduino sketch and my own upcoming verion of the arduino sketch, can be found on: http://en.techmind.dk/arduino/inverter-12-volt-to-230-volt-with-arduino/
I made a english version to place some of my arduino experiments and projects
Remember the general disclaimer: 'if you play with electricity, it is at your own risk, and only you are responsible for the danger in this kind of projects'
hope you find the inverter usefull