Abstract: The photovoltaic system includes an inverter, a fan, and a controller. A photovoltaic string and a direct current bus capacitor are connected between a positive input end and negative input end of the inverter. The controller receives a fast shutdown instruction and sends a drive signal to a switching transistor in the inverter, so that the switching transistor performs a switching action under the action of the drive signal, and the switching transistor consumes electric energy during the switching action; or the controller turns on the fan after receiving the fast shutdown instruction to consume electric energy by using the fan; or the controller may send the drive signal to the switching transistor and also control the fan to be turned on, so that both the switching transistor and the fan consume electric energy.

Abstract: A photovoltaic power generation system and a method and a device for detecting an earth fault of a photovoltaic string. The controller obtains a terminal voltage of each photovoltaic string before voltage disturbance, where the terminal voltage is a voltage to earth of a positive electrode or negative electrode of the photovoltaic string; performs voltage disturbance on each photovoltaic string and obtains a terminal voltage of each photovoltaic string after the voltage disturbance; determines a photovoltaic string with an earth fault based on the terminal voltage of each photovoltaic string before and after the voltage disturbance; obtains a photovoltaic panel with an earth fault by using the terminal voltage and an output voltage of the photovoltaic string before the voltage disturbance, or obtains a photovoltaic panel with an earth fault by using the terminal voltage and an output voltage of the photovoltaic string after the voltage disturbance.