Hydrogen production in a PV concentrator using III-V multi-junction solar cells

Multi-junction solar cells from III-V compound semiconductors can generate ideal voltages for the electrolysis of water. This paper presents results of a PV-concentrator HyConreg with Ga0.35In0.65P/Ga0.83In0.17As tandem solar cells which are directly connected to the electrodes of a local polymer electrolyte membrane electrolyser. This electrolyser is integrated into the base plate of a concentrator module. A prototype system with an area of 96 cm2 has been realized. The solar to hydrogen conversion efficiency of this system was measured outdoor in Freiburg to be 18.2% (based on the thermoneutral voltage of 1.485 V).