Development of FLATCON® modules using secondary optics

In this paper we report on research activities at the Fraunhofer Institute for Solar Energy Systems (ISE) and Concentrix Solar in the area of secondary optics for FLATCON^® modules. This concentrator photovoltaic (CPV) technology is based on Fresnel-lenses as primary optics, passive heat spreaders and triple-junction III-V solar cells. In the first part of the paper, a field performance analysis is presented for Concentrix CPV-systems recently installed in Spain. Subsequently, the performance of the first FLATCON^® modules with reflective and refractive secondaries are evaluated (FLATCON^® II) in indoor and outdoor measurements. As a result of this development, the first module with automated assembly process of the secondary optics could be manufactured. The highest outdoor efficiency measured for this kind of module is 29.1 %, which is the highest module efficiency achieved at the Fraunhofer ISE so far.