Electricity generation of GeSn single-junction solar cell has been carefully examined in both its p-on-n and n-on-p configurations in its normal and inverted structures. The superior p + /n construction with a critical doping of the light-doped layer (N d = 7.5 Â 10 18 cm À3 ) has been observed. For the normal one, the active layer should be composed of 50-100 nm emitter and 3-5 μm base to less material costs. Moreover, dislocation density and 1 MeV electron fluence should be lower than 1 Â 10 5 cm À2 and 1 Â 10 10 cm À2 , respectively, which is helpful for obtaining a preferable conversion efficiency. To explore lower cost solar cell, the simulated results might be favorable to guide experimental fabrication of GeSn devices.