Numerical two dimensional modeling of silicon solar cells with experiment validation

A two dimensional numerical model for silicon solar cells has been developed in COMSOL. This model calculates the influence of emitter doping profile, sheet resistance, and recombination on the performance of the solar cell in two dimensions. The solar cell model has an n⁺ p p⁺ structure with a measured doping profile in the emitter and uniformly doped back surface field. The surface recombination velocity at the front surface is calculated based on the surface doping density. The carrier flow pattern in the solar cell was analyzed by solving the diffusion equations using appropriate boundary conditions. The numerical model was developed in COMSOL by solving the Poisson equation, the current density equation and the continuity equation in each region. An important design parameter of conventional Si solar cells is the emitter region and determining its influence on front contact spacing. This model can also be used for optimizing the front contact design. The model uses finite element analysis for these calculations. Solar cells have been fabricated with various emitter doping profiles and are characterized. Experimental I-V characteristics and IQE response values are compared with simulation results.