The effect of concentration distribution on the performance of a static concentrator cell with a new three-dimensional lens was investigated to design an optimum cell structure. A concentration distribution of this lens was simulated using a ray-tracing method. Based on these results, fill factors were calculated as a function of series resistance and irradiance to clarify the effect of concentration distribution. The effect of concentration distribution appeared when series resistance is larger than 0.2 Omega cm(2) and irradiance is higher than 30 mW/cm(2).