Fig. 1. (Color online) (a) A digital camera image of a PERC solar cell with five busbars from our product line. (b) Schematic illustration of the basic PERC solar cell structure in the simulation.

Fig. 2. The J–V curve of PERC reference cell and the electrical properties comparison between simulated and practical mass-produced PERC cell.

Fig. 3. (Color online) The relationship between the saturation current density J_0E and sheet resistance of SiO_xN_y/SiN_x^[26], SiO₂/SiN_x^[25], SiO₂/Al₂O₃/SiN_x^[25] and Al₂O₃/SiN_x^[25] passivation layers on n⁺ emitter of PERC solar cell.

Fig. 4. (Color online) Comparison of (a) simulated efficiency and V_OC, (b) simulated J_SC and FF of PERC solar cells using different n⁺ emitter passivation stacked layers.

Fig. 5. (Color online) Relationship between resistivity and carrier lifetime of silicon wafer under intrinsic limit condition and different BO deactivated processing conditions^[29–31].

Fig. 6. (Color online) The electrical performance of PERC solar cells varies with the resistivity of silicon wafers under intrinsic limit and different BO deactivated processing conditions^[29–31].

Fig. 7. (Color online) Simulated solar cell of a possible scenario for further PERC cell improvements. In step (1), the star, triangle, circle and rhombus points represent cells with SiO₂/SiN_x, SiO₂/Al₂O₃/SiN_x, SiO_xN_y/SiN_x and Al₂O₃/SiN_x, respectively. In step (2), the star, rhombus and circle points represent carrier lifetimes of 6200, 2500, and 430 μs, respectively. In step (3), the hollow star represents the cell with 12 BB and the solid star represents the cell using 12 BB together with Ni/Cu electrode.

Fig. 8. (Color online) Sources of the efficiency loss between the simulated PERC solar cell with 24.04% to the limit efficiency of 29%.

Table 1. Simulation parameters of PERC reference cell.

Table 2. Comparison of resistivity and contact resistivity of different metal electrode^[21].