Sensitivity Analysis of Industrial Multicrystalline PERC Silicon Solar Cells by Means of 3-D Device Simulation and Metamodeling

How successfully an improved solar cell concept is transferred to mass production depends not only on the realized cell efficiency, but crucially on the stability of the fabrication process, i.e., on the distribution of the current-voltage (I-V) parameters. To model such distributions, we use three-dimensional (3-D) full-size device simulations of passivated emitter and rear cells (PERCs). The number of these time-consuming simulations is drastically reduced by changing all input parameters concurrently in a design of experiment approach. A simple polynomial response surface methodology (RSM) model is obtained from these simulations by regression analysis. The RSM contains all the mutual nonlinear interactions between the device parameters, and is therefore called a metamodel. The metamodel is applied: 1) to find maximum efficiency; 2) to compute how sensitively each device parameter influences the I-V parameters; 3) to explain, predict, and manipulate the distribution of the I-V parameters in mass production; and 4) to find an optimum starting point for experiments. For example, we demonstrate how the choice of the distance between the rear local point contacts leads to either maximal median efficiency but with a broad distribution, or to a slightly reduced median cell efficiency but with a narrow distribution and a reduced number of bad cells.