An inverting apparatus and a photovoltaic power system using the same are provided. The inverting apparatus includes an inverting circuit, a control circuit, and a voltage regulator-based ground detection circuit. The control circuit controls the power conversion of the inverting circuit. The voltage regulator-based ground detection circuit samples an input voltage of the DC input power, and performs voltage regulation and voltage division on the input voltage to generate a ground indication voltage. The electric potential of the output terminal of the voltage regulator is built based on a photovoltaic ground terminal of a photovoltaic module. The ground indication voltage is the voltage difference between an output terminal of the voltage regulator and a device ground terminal of the inverting apparatus. The control circuit determines whether a ground fault occurs to the photovoltaic module and enables a ground protection mechanism to control the inverting circuit when the ground fault occurs.