Efficiency dispersion in production of crystalline-Si solar cells by numerical simulation

Efficiency dispersion in crystalline-Si solar cells is a major contributor to the high cost of Si PV systems. A comprehensive sensitivity analysis for efficiency dispersion in the production of crystalline-Si solar cells is presented based on numerical simulations. Various process variables are considered, including temperature variation in the diffusion furnace, wafer resistivity and finger electrode width. The simulation provides a quantitative estimation for efficiency variation due to each of these process variables. It is suggested that temperature variations in the diffusion furnace are the biggest cause for efficiency dispersion, when a 60°C temperature variation results in an efficiency drop of almost 6% absolute. To understand the effect of diffusion temperature, factors related to diffusion such as contact resistivity, emitter resistance and emitter recombination are also investigated to reveal their individual effect on cell efficiency. Resistive losses in the emitter are primarily responsible for the efficiency variation. Remedies for efficiency dispersion are proposed.