A photovoltaic inverter, a photovoltaic system, and a method for controlling discharging are provided. The photovoltaic inverter includes a first DCDC converter, an inverter circuit, a first discharging circuit, and a controller. A port capacitor is connected between a positive input end and a negative input end of the first DCDC converter. The port capacitor includes an X capacitor and a first group of Y capacitors. The first discharging circuit is connected between a common terminal of the first group of Y capacitors and a direct current bus, where the common terminal of the first group of Y capacitors is grounded. The controller is configured to control, when receiving a rapid shutdown instruction, the first discharging circuit to operate. The first discharging circuit is configured to discharge electrical energy of the port capacitor.