Design considerations for industrial rear passivated solar cells

In this work, the solar cell development issues arising by adding a dielectric rear side passivation to a standard screen-printing process are discussed with deposited Al₂O₃ on p-type Cz-Si as an example. The influence of several design parameters is assessed in simulation and experiment and an optimization strategy is presented. These parameters include optical properties of the cell, like the choice of dielectric layer thickness and wafer surface roughness, parameters that influence the passivation quality like the temperature of the co-firing step in a belt furnace as well as electrical parameters like contact geometry, contact spacing and base resistivity. Their influence on the three efficiency-determining quantities, V_OC, J_SC and FF is outlined. Special attention is paid to minimizing the inevitable loss in FF in a PERC design.