Embodiments of this application disclose a fault point position determining method and apparatus and a photovoltaic system, to correctly and efficiently determine a fault point position when a disconnection fault occurs in a photovoltaic system. The method is applied to a photovoltaic system, the photovoltaic system includes at least one inverter and at least one photovoltaic unit, each photovoltaic unit includes at least one photovoltaic module and one photovoltaic module controller, and the method includes: sending, by an 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.