A photovoltaic system including multiple photovoltaic cell strings, a converter, a controller, and a bus is presented. The multiple photovoltaic cell strings include at least one string group in which parallel-connected photovoltaic cell strings are coupled to one current sensor, where the at least one string group, after being connected in parallel, is coupled to the converter using the bus, the current sensor is configured to detect a total current of each string group, the controller is configured to adjust, when receiving a report from the current sensor that a reverse current exists in a target string group in the at least one string group, a control signal output to the converter, and the converter is configured to decrease, according to an adjusted control signal, a system voltage between the buses to decrease the reverse current in the target string group.