Series resistance (R,) is considered to be one of the most important parameters affecting solar cell performance, especially those operating under concentrated solar radiation. Many methods have been proposed where the estimated R, values do not coincide or even come close to each other In this paper seven methods for determining R, are reviewed and verified experimentally using a commercial single-crystal silicon solar cell (104 cm 2 of total area). Their differences lie principally in: (1) number of diodes quoted in the solar cell model; (2) other assumptions (constant ideality factor or not, infinite, or finite shunt resistance); and (3) simultaneous determination of other parameters or not. Based on these methods, R, values were derived by extracting the necessary parameters from the measured I-V characteristics of the cell at different illuminations and cell temperatures. According to these methods, the obtained R-s values varied greatly in comparison with each other as well as its trend with temperature variation.