The present disclosure relates to a grid-tied photovoltaic power generation system, and particularly, to a grid-tied photovoltaic power generation system including a power maintaining unit configured to maintain power of a controller during an corresponding operation time of a photovoltaic system when power supply is stopped due to a fault generated in a grid, whereby power may be stably supplied to the controller and power of the controller may be maintained, designing of the photovoltaic system and setting of a connection to the grid may be simply and easily performed, a corresponding operation of the photovoltaic system may be controlled regarding the fault generated in the grid, and the fault generated in the grid may be accurately, appropriately, and effectively handled.