Laser based foil rear side metallization for crystalline silicon solar cells

In this contribution we present different results of our investigations regarding the use of aluminum foil as rear side metallization for solar cells with dielectric passivation and laser fired contacts (LFC). We investigate the impact of different laser processes on the resistance of the contacts, the adhesion properties of the foil and the efficiency potential. By fabricating highly efficient, 20×20 mm2 sized solar cells with a conversion efficiency of 21.0 %, we demonstrate the high potential of this approach, which is equal to that of LFC-cells with common screen-printed or PVD metallization on the rear side. We investigated the optical properties of such metallized rear sides which benefit from an embedded air gap between foil and passivation layer. Finally, we present first solar cell results on industrially sized wafers (A=238 cm2) demonstrating again the equal efficiency potential compared to PVD metallization.