A physical address determining method, applied to a photovoltaic power generation system, wherein the photovoltaic power generation system comprises a master node and a plurality of photovoltaic strings (11, 21); an output end of each photovoltaic string is connected to an input end of the master node; each photovoltaic string comprises at least one photovoltaic power generation group; each photovoltaic power generation group comprises one photovoltaic module and one slave node; when any photovoltaic string comprises at least two photovoltaic power generation groups, the at least two photovoltaic power generation groups are connected in series; and the method comprises: controlling at least two slave nodes in the photovoltaic power generation system to sequentially start up, and the method is characterized in that it further comprises detecting a change status of an input voltage of the master node; based on the detected change status, grouping any two slave nodes for which a superposition phenomenon occurs on the input voltage during sequential startup and corresponding photovoltaic modules into a same photovoltaic string (11, 21), and grouping any two slave nodes for which no superposition phenomenon occurs on the input voltage during sequential startup and corresponding photovoltaic modules into different photovoltaic strings, to obtain a plurality of photovoltaic strings, wherein the superposition phenomenon is a phenomenon that an amplitude increment in the input voltage is within a preset neighborhood range of unit amplitude, the unit amplitude is amplitude of the input voltage of the master node when only one slave node starts up, and the preset neighborhood range is a numerical range centered on the unit amplitude; when at least two slave node quantities in configuration data are equal, determining, from the plurality of photovoltaic strings (11, 21) obtained through grouping, a photovoltaic string whose slave node quantity is equal to the at least two slave node quantities, as a candidate photovoltaic string, wherein the configuration data comprises a slave node quantity of each photovoltaic string and a physical address of each photovoltaic string; and for each determined candidate photovoltaic string (11, 21), controlling any slave node located in the candidate photovoltaic string to start up and slave nodes other than the any slave node in the photovoltaic power generation system to shut down, determining a physical address of a photovoltaic string that has an input voltage or an input current, and using the physical address as a physical address of the candidate photovoltaic string. controlling at least two slave nodes in the photovoltaic power generation system to sequentially start up, and the method is characterized in that it further comprises detecting a change status of an input voltage of the master node; based on the detected change status, grouping any two slave nodes for which a superposition phenomenon occurs on the input voltage during sequential startup and corresponding photovoltaic modules into a same photovoltaic string (11, 21), and grouping any two slave nodes for which no superposition phenomenon occurs on the input voltage during sequential startup and corresponding photovoltaic modules into different photovoltaic strings, to obtain a plurality of photovoltaic strings, wherein the superposition phenomenon is a phenomenon that an amplitude increment in the input voltage is within a preset neighborhood range of unit amplitude, the unit amplitude is amplitude of the input voltage of the master node when only one slave node starts up, and the preset neighborhood range is a numerical range centered on the unit amplitude; when at least two slave node quantities in configuration data are equal, determining, from the plurality of photovoltaic strings (11, 21) obtained through grouping, a photovoltaic string whose slave node quantity is equal to the at least two slave node quantities, as a candidate photovoltaic string, wherein the configuration data comprises a slave node quantity of each photovoltaic string and a physical address of each photovoltaic string; and for each determined candidate photovoltaic string (11, 21), controlling any slave node located in the candidate photovoltaic string to start up and slave nodes other than the any slave node in the photovoltaic power generation system to shut down, determining a physical address of a photovoltaic string that has an input voltage or an input current, and using the physical address as a physical address of the candidate photovoltaic string.