III-V multi-junction Metal-Wrap-Through (MWT) concentrator solar cells
III-V multi-junction solar cells are promising devices for photovoltaic applications under very high concentration levels of sunlight. Shadowing losses of the front side metallization and ohmic resistance losses in the metal grid limit the practical cell size typically to around 1 cm2 at 800 suns. The use of a full back-contact architecture, similar to the Metal Wrap-Trough (MWT) technology known in silicon photovoltaics, can help to overcome this limitation. Furthermore, positioning both the positive and negative contact pads on the rear side of concentrator solar cells opens the possibility for efficient packaging solutions and the realization of dense array receivers with low metal shadowing. The MWT technology addresses conventional concentrating photovoltaics as well as combined PV-thermal applications and offers specific advantages for large area devices at high intensities. This work presents first experimental results for MWT architectures applied to III-V tandem solar cells and discusses specific challenges. An efficiency of 28.3 % at 176 suns and 27.2% at 800 suns has been measured for the best MWT Ga0.51In0.49P/Al0.03Ga0.97As tandem solar cells.