Abstract: In order to improve the conversion efficiency of solar cells and to reduce production costs,a fractional power loss model is developed through analyzing the power loss mechanism of solar cells. The optimized shape and size parameters of front electrode grid of the solar cell are obtained by solving the fractional power loss model. The conversion efficiency of solar cells can be obtained by using simulation software PC1D. The simulation results make a good agreement with that of theoretical analyses. Comparing with a solar cell having a constant width front electrode grid structure,when the number of the busbar is from 2 to 6,The conversion efficiency of a solar cell with an unequal width busbar structure is increased by 0.10%,0.09%,0.10%,0.09% and 0.09%;The total volume of busbars is decreased by 0.72,0.68,0.64,0.58 and 0.47 mm~3;The increment of total volume of fingers is less than 0.07 mm~3. It indicates that the front electrode grid structure with an unequal width busbar has a higher conversion efficiency and a lower silver paste usage.