Concentrating photovoltaic (CPV) systems based on III-V semiconductors entered the photovoltaic market recently. Concentrix Solar deploys the FLATCON® CPV module technology originally developed at the Fraunhofer Institute for Solar Energy Systems ISE. This paper gives a short introduction in design considerations of FLATCON CPV module and provides detailed field data of the system technology over up to two years are presented as well as field experiences with the operation of the systems. FLATCON modules are based on III-V triple junction cells, a Fresnel lens array, and a glass cover and bottom plate. In 2008, Concentrix installed a single tracker system and two power plants in Spain. A system solar-to-grid AC energy efficiency of 21% over the whole period of two years with maximum system AC power efficiency values of 23% for a single tracker system are shown. Similar systems installed in 2009 and equipped with the current FLATCON module CX-75 achieved system AC power efficiencies of 25%. The effects of spectral variations of the solar irradiation on power plant performance are discussed.