50Prozent / 50Percent – Monolithic III-V Multi-Junction Solar Cells with More than 50 % Efficiency under Concentrated Irradiation

The primary goal of the 50Percent project is to produce the first multi-junction solar cell with an efficiency value of 50% and a concentrator module with 40% efficiency. The project also seeks to develop measuring technology so that the cells can be measured in accordance with internationally recognized calibration standards. The project aims to impressively demonstrate German PV research excellence.

The efficiency value of a solar cell or solar module is the key characteristic that distinguishes PV technologies from one another. This value not only determines the amount of energy that can be harvested from a limited area, it is also decisive when it comes to costs, resource consumption and thus the sustainability of solar energy production. A growing understanding of highly efficient solutions additionally promotes the optimization of production processes and with it the competitiveness of the German photovoltaics industry. Fraunhofer ISE, SOITEC and CEA share the record for the most efficient solar cell in the world with a 46% efficiency value under concentrated sunlight. At 508 times the concentration, this value has been confirmed by the internationally recognized calibration laboratory AIST in Japan. Despite intensive international efforts made in the past 4 years, it has not yet been exceeded. The goal of the 50Percent project is to use existing expertise in conjunction with new findings to develop a multi-junction solar cell with 50% efficiency. Simulation calculations show that this goal can be achieved through systematic continued development of established technologies in combination with shadow-reduced metal fingers and an improved anti-reflective layer. The new infrastructure required for this became available at the Fraunhofer ISE’s Center for High-Efficiency Solar Cells in summer 2020. Furthermore, the setup of this measurement technology is intended to enable the measurement of solar cells with up to 6 sub-cells under spectrally adapted conditions. The new multi-junction solar cells are used in FLATCON® concentrator modules, where a module efficiency of over 40% is expected for the first time. The 50Percent project aims to impressively demonstrate the excellence of applied photovoltaic research in Germany by setting new record efficiencies for solar cells and concentrator modules.