The invention discloses a photovoltaic inverter system and a method for controlling the same. The photovoltaic inverter system comprises: an optimizing module string and an inverter, wherein the optimizing module string comprises a plurality of optimizing modules each having an input port coupled to at least one photovoltaic module, output ports of the plurality of optimizing modules are connected in series, each of the optimizing modules comprises a control unit, an input port of the inverter is coupled to an output port of the optimizing module string, the inverter comprises an auxiliary detection module for auxiliary detecting an output current of the optimizing module string, and the control unit controls an output voltage of the optimizing module string based on the output current of the optimizing module string, such that the output voltage satisfies a start-up condition of the inverter.