GaInP/AlGaAs metal‐wrap‐through tandem concentrator solar cells

Abstract

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 metallisation and ohmic resistance losses in the metal grid limit the practical cell size typically to around 1 cm2 at 1000 suns. The use of a full back-contact architecture, similar to the metal-wrap-through (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 realisation of dense array receivers with low metal shadowing. The MWT technology addresses conventional concentrating photovoltaics as well as combined conventional concentrating photovoltaic-thermal applications and offers specific advantages for large-area devices at high intensities. This work presents the 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

The handling of thin substrates and its potential for new architectures in multi-junction solar cells technology

“…Modelling has shown that this approach is especially interesting at high concentration and could not only improve the cell efficiency by 3 absolute percent compared to conventional top electrodes, but also increase the total power generation per wafer by ~20% considering the bus bar suppression. Despite its considerable potential, only one prototype has been fabricated for tandem III-V solar cells and showed non-optimal electrical results, in particular because of current leakage and cell architecture 9 . Indeed, the full fabrication method requires to revisit the process flow for solar cells fabrication, and necessitates the development of vias fabrication, including via etching, insulation and metallization.…”