InGaP/InGaAs/Ge triple junction solar cells with a size of 26.5 cm2, thickness of 120+/- 20 μm and AM0 efficiency class 30% (CTJ30%), have been manufactured and qualified following the ESA ECSS E ST20-08 standard.
These solar cells have been developed on a large MOCVD epitaxial reactor, VEECO E450G, suitable to simultaneously process up to thirteen 4-inch wafers per run.
The improvement in conversion efficiency was obtained by introducing Quantum Structures, mainly Bragg Reflectors, inside the solar cell stack and a fine tuning of the electrical field inside the solar cell active regions .
These solar cells are going to power the Kvant constellation named Meteor M and Kanopus. Next generation of the Russian spacecraft requires more specific power, for this reason new solar cell approaches based on III-V on silicon and ultrathin substrate are under development. The main advantage of these technologies lie in the possibility to strongly decrease weight and cost of III-V solar cells for space applications.
 G. Gori, R. Campesato: Photovoltaic Cell Having a high Conversion Efficiency PCT I09111-WO (2009)