A fault point position determining method, wherein the method is applied to a photovoltaic system, the photovoltaic system comprises at least one inverter and at least one photovoltaic unit, the photovoltaic unit comprises at least one photovoltaic module and one photovoltaic module controller, and the method comprises: sending, by the inverter, a first test signal to the at least one photovoltaic unit; obtaining, by the inverter, first test signal characteristic information fed back by the at least one photovoltaic unit; and performing, by the inverter, absolute value or relative value sorting on the at least one piece of first test signal characteristic information, and determining a fault point in the photovoltaic system based on a sorting result, wherein after the sending, by the inverter, a first test signal to the at least one photovoltaic unit, the method further comprises: determining, by the inverter, that the inverter obtains no first test signal characteristic information fed back by the at least one photovoltaic unit, when the inverter determines that the characteristic information of the first test signal fed back by the at least one photovoltaic unit has not been acquired sending, by the inverter, a second test signal to the at least one photovoltaic unit, wherein a frequency of the second test signal is different from a frequency of the first test signal; obtaining, by the inverter, second test signal characteristic information fed back by the at least one photovoltaic unit in response to the second test signal, wherein the at least one photovoltaic unit measures the received second test signal to obtain the second test signal characteristic information; and determining the fault point in the photovoltaic system, by the inverter, based on absolute value or relative value sorting on the at least one piece of second test signal characteristic information. sending, by the inverter, a first test signal to the at least one photovoltaic unit; obtaining, by the inverter, first test signal characteristic information fed back by the at least one photovoltaic unit; and performing, by the inverter, absolute value or relative value sorting on the at least one piece of first test signal characteristic information, and determining a fault point in the photovoltaic system based on a sorting result, wherein after the sending, by the inverter, a first test signal to the at least one photovoltaic unit, the method further comprises: determining, by the inverter, that the inverter obtains no first test signal characteristic information fed back by the at least one photovoltaic unit, when the inverter determines that the characteristic information of the first test signal fed back by the at least one photovoltaic unit has not been acquired sending, by the inverter, a second test signal to the at least one photovoltaic unit, wherein a frequency of the second test signal is different from a frequency of the first test signal; obtaining, by the inverter, second test signal characteristic information fed back by the at least one photovoltaic unit in response to the second test signal, wherein the at least one photovoltaic unit measures the received second test signal to obtain the second test signal characteristic information; and determining the fault point in the photovoltaic system, by the inverter, based on absolute value or relative value sorting on the at least one piece of second test signal characteristic information. determining, by the inverter, that the inverter obtains no first test signal characteristic information fed back by the at least one photovoltaic unit, when the inverter determines that the characteristic information of the first test signal fed back by the at least one photovoltaic unit has not been acquired sending, by the inverter, a second test signal to the at least one photovoltaic unit, wherein a frequency of the second test signal is different from a frequency of the first test signal; obtaining, by the inverter, second test signal characteristic information fed back by the at least one photovoltaic unit in response to the second test signal, wherein the at least one photovoltaic unit measures the received second test signal to obtain the second test signal characteristic information; and determining the fault point in the photovoltaic system, by the inverter, based on absolute value or relative value sorting on the at least one piece of second test signal characteristic information.