A photovoltaic system, wherein the photovoltaic system comprises an inverter and a plurality of photovoltaic units connected to the inverter, each photovoltaic unit comprises a controller and one or more photovoltaic modules connected to the controller, the photovoltaic module is configured to convert radiant energy of sunlight into a direct current, the controller is configured to regulate an output status of the one or more photovoltaic modules, and the inverter is configured to convert a direct current output by the photovoltaic unit into an alternating current and output the alternating current; the controller in each photovoltaic unit is further configured to obtain a power carrier signal sent by a controller in another photovoltaic unit of the plurality of photovoltaic units, determine an attenuation reference factor of the power carrier signal based on the obtained power carrier signal, and send the attenuation reference factor to the inverter, wherein the power carrier signal carries identification information of the controller that sends the power carrier signal, and the attenuation reference factor is used to reflect an attenuation degree of signal attenuation of the power carrier signal in a process of being transmitted, to the controller in the photovoltaic unit, from the controller that is in the another photovoltaic unit and that is indicated by the identification information in the power carrier signal; and the inverter is further configured to: determine, based on the attenuation reference factor, the attenuation degree of the power carrier signal obtained by the controller in each photovoltaic unit, group the plurality of photovoltaic units based on the attenuation degree of the power carrier signal obtained by each photovoltaic unit and, when an attenuation degree of a power carrier signal that is obtained by a controller in a photovoltaic unit and that is sent by a controller in another photovoltaic unit is less than or equal to a reference threshold, determine that the photovoltaic unit and the another photovoltaic unit belong to a same photovoltaic unit group. the controller in each photovoltaic unit is further configured to obtain a power carrier signal sent by a controller in another photovoltaic unit of the plurality of photovoltaic units, determine an attenuation reference factor of the power carrier signal based on the obtained power carrier signal, and send the attenuation reference factor to the inverter, wherein the power carrier signal carries identification information of the controller that sends the power carrier signal, and the attenuation reference factor is used to reflect an attenuation degree of signal attenuation of the power carrier signal in a process of being transmitted, to the controller in the photovoltaic unit, from the controller that is in the another photovoltaic unit and that is indicated by the identification information in the power carrier signal; and the inverter is further configured to: determine, based on the attenuation reference factor, the attenuation degree of the power carrier signal obtained by the controller in each photovoltaic unit, group the plurality of photovoltaic units based on the attenuation degree of the power carrier signal obtained by each photovoltaic unit and, when an attenuation degree of a power carrier signal that is obtained by a controller in a photovoltaic unit and that is sent by a controller in another photovoltaic unit is less than or equal to a reference threshold, determine that the photovoltaic unit and the another photovoltaic unit belong to a same photovoltaic unit group. determine, based on the attenuation reference factor, the attenuation degree of the power carrier signal obtained by the controller in each photovoltaic unit, group the plurality of photovoltaic units based on the attenuation degree of the power carrier signal obtained by each photovoltaic unit and, when an attenuation degree of a power carrier signal that is obtained by a controller in a photovoltaic unit and that is sent by a controller in another photovoltaic unit is less than or equal to a reference threshold, determine that the photovoltaic unit and the another photovoltaic unit belong to a same photovoltaic unit group.