Disclosed is a photovoltaic system including a power optimizer, capable of minimizing noise occurring due to shading, an error in an output power of a photovoltaic module, etc. while a maximum power point tracking (MPPT) algorithm is performed. The photovoltaic system includes a photovoltaic module; a power optimizer; and an inverter, wherein the power optimizer includes: an input unit configured to receive an output power of the photovoltaic module; a sensing unit configured to sense an output voltage and an output current of the photovoltaic module; and a controller configured to control an output of the power optimizer, by comparing the presently-sensed current with a previously-sensed current.