2-D numerical analysis of current collection in silicon solar cells

An important aspect of solar cell design is top contact optimisation. A metallisation technology has characteristics of contact resistivity, a lower bound on finger width and the location of cell interconnections. The geometry of the top contact must be optimised taking into account those characteristics. Improvements in the geometry, although resulting in small performance gains, can be worthwhile because they do not imply extra fabrication costs. To obtain these improvements it is important to be able to simulate general geometries and hence two-dimensional effects in the potential distributions as well as the effect of the variations in emitter potential on the local current collection. The authors describe how a comprehensive and flexible program has been developed which analyses current collection in 2 lateral dimensions by numerical means. A finite difference method on a rectangular grid is employed to discretise the coupled Poisson equations, leading to systems of nonlinear equations