The multi-junction solar cells developed in the project will be installed and tested in a FLATCON® concentrator module. At Fraunhofer ISE, this module concept has been developed and continuously optimized over the last 20 years. In WP5, the focus length and anti-reflection layer are adapted to the new cell structure. Furthermore, solar cell assemblies are manufactured and individually measured in order to select the best solar cells for module construction. Subsequently, a FLATCON® module with an area of 1088 cm2 will be built and measured on a 2-axis tracking unit. The goal is to achieve a new module record of 40% under CSTC conditions and to qualify this value for an entry in the Progress in Photovoltaics efficiency tables.