Geometric parameters are an important data for the choice of solar cell architecture, for better conversion performance. As poor optoelectronic material is used, i.e. short minority carrier's diffusion length and under concentrated light which increases the temperature, it is then important to optimize the width of the lamella in order to have better photogenerated charge collection. Thus the intent of this work is the determination of the width of the lamella structure, presented through phenomelogical parametersmodeling study. These are the diffusion length and coefficient, as well as the surfacerecombination velocity of the photogenerated carriers in the base of the lamella silicon. The result gives a mathematical relationship between the optimum width and the operating temperature of the lamella solar cell, allowing to influence the industrial manufacturing process for the material economy.