I repaired a chinese grid tie inverter for small solar systems, Input 50-100V, Output 230V 300W. The failure was in the reference voltage inside the µC ATMega8, it dropped down arbitrary. To be able to find this failure, I had to re-engineer the complete set and had to draw the schematics by my own. I share this here to help other insane electrophile humans to get familiar with grid tie inverters.