# Frequency synchronization

#### polo87

##### New Member
Hello... I`m new here, Like your fourm vary mach .

I need help with my project.
I need to understand how Frequency synchronization in grid-tie inverter works.
when I say Frequency synchronization I meen Frequency synchronization bettwen the inverter output voltage and the grid voltage so I be able to feed the power back to the grid.

and now more question .
I understand that the inverter output voltage has to been slightly higher then the grid voltage. how much higher it has to be?? 1% more?