There are provided a power converting apparatus and an operating method thereof, and a solar power generation system. The power converting apparatus for a solar power generation system includes: a power converting unit converting an input signal generated by a solar cell module into an output signal; and a control circuit unit controlling an operation of the power converting unit, wherein the power converting unit includes at least one transformer, and a current sensor and a switching circuit connected to a primary winding of the at least one transformer, and the control circuit unit calculates a voltage and a current of the input signal using a current of the primary winding of the at least one transformer sensed by the current sensor and performs a maximum power point tracking (MPPT) control so that the power converting unit is operated at a maximum power point.