Abstract: In order to obtain more efficient and reasonable calculation conditions and methods for the number of PV module series connections,this paper selected 119 proposed project sites located at different latitudes and climate types. Based on PVLIB and NASA meteorological data,20 years of hourly meteorological data are obtained for the 119 proposed project sites. The open circuit voltage of PV modules and their corresponding number of PV module series connections obtained under different calculation conditions are analyzed. The analysis results show that the number of PV modules connected in series calculated based on 200 W/m~2 solar irradiance and historical lowest temperature is similar to the number of PV modules connected in series calculated based on multi-year hourly meteorological data. The calculation method is relatively simple and does not require long-term hourly meteorological data. It can be used as a calculation condition for the number of PV modules connected in PV power plant design.