Simulation of lateral effect in emitter region of silicon solar cells for concentrated sunlight

Abstract

The loss due to lateral current flow in top diffused layer is one of the most important mechanisms of loss associated with top contacts and can be a limiting factor causing the reduction of cell efficiency especially for cells made to operate at high sun concentrations, because of higher level of current density and voltage drop. To optimize the design of grid contact, it is necessary to know the exact distributions of voltage and lateral and vertical current densities. In this work, a common structure of silicon solar cell is simulated at different levels of sun light concentrations where the lateral current density and voltage distributions are examined for different depths of emitter layer and bias voltages. In addition, the effect of lateral distribution of diffused layer on output power and efficiency for different illuminations is described. Also voltage and lateral current distributions in two bias voltages (maximum power voltage and open circuit voltage) and the influence of illumination are modeled by some analytical functions.