In the last years, several high conversion eciencies have beenreported7,8. There are mainly two technologies responsible forthis progress: first, the passivated contact technology includingheterojunctions (HJ); and second, the interdigitated back contact(IBC) technology. The HJ technology using an amorphous Si (a-Si)layer to passivate the crystalline Si (c-Si) surface was first reported bySanyo (now Panasonic) and following work was reported in 20009.The very origin of the IBC design was first suggested in 197710 andan ecient solar cell was reported in 198411.