Mitigating Cut Losses in Interdigitated Back Contact Solar Cells

The edge recombination losses of crystalline silicon solar cells become significant when they are cut into smaller pieces to be assembled into modules. With the interdigitated pattern of doped $p$ and $n$ regions on the rear side, the interdigitated back contact (IBC) solar cells can be cut through different doped regions. In this study, the cutting losses in IBC solar cells are investigated and various cutting scenarios are studied. Through simulations and experimental measurements, it is found that the cut losses can be reduced by cutting through the back surface field rather than through the emitter. The losses under low light intensity are reduced to an even greater extent. When a 23% cell is cut into 1/3 pieces, the efficiency can be increased by 1.2% $_\mathrm{rel}$ (cut related losses were improved from 2.0% $_\mathrm{rel}$ to 0.8% $_\mathrm{rel}$ ) under standard 1-sun testing conditions, compared to cutting through the emitter. Under low light intensity of 0.25 sun, the improvement is around 2.4% $_\mathrm{rel}$ . The improvement is mainly due to lower FF losses in the I–V characteristics, and this is further confirmed by Suns– $V_{\text{oc}}$ and PL measurements. In the pFF analysis, the additional losses due to laser damage are also observed. This strategy of cutting through the BSF region in IBC solar cells can be quickly adopted in mass production without the need for additional processes or equipment and both module power and energy yield can be increased.