Two-Dimensional Modeling of EWT Multicrystalline Silicon Solar Cells and Comparison with the IBC Solar Cell

In this study two-dimensional (2D) computer simulations of the n
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pn
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emitter-wrap-through (EWT) cell structure with industrially relevant parameters is performed and a comparison is made with p-type substrate interdigitated back contact (IBC) cells. Our simulation results show that the EWT cell is particularly suited for low bulk lifetimes and thin substrates. Simulation results indicate that achieving a lifetime of around 45 mus will be sufficient to realize very high-efficiency EWT cells. The effect of different cell parameters (e.g., surface recombination velocities, thickness, bulk resistivity, bulk lifetime, cell geometry, etc.) is explored. The EWT cell shows much higher robustness to poor material lifetime as well as surface passivation compared to the IBC cell. While a 1 ms lifetime IBC cell drops to efficiencies less than 14.5% for an intrinsic surface recombination velocity (SRV) of 10,000 cm/s, the EWT cell can maintain efficiencies above 15% at a much lower bulk lifetime of 30 mus and higher SRV of 300,000 cm/s