KosmoS (Cost-Optimised, High-Efficiency Solar Cells Made of Low-Oxygen N-Type Mono Silicon for Industrial Mass Production)

  • Funding institution: German Federal Ministry for Economic Affairs and Energy (BMWi)
  • Support code: 0325822E
  • Duration: 05/2015 to 04/2018
  • Consortium: ISC Konstanz, RCT Solutions, PV Crystalox Solar Silicon, PVA TePla, Fraunhofer CSP


In 2014, following many years of optimising the Al-BSF standard process, a sustainable trend began in the solar industry towards upgrading existing production lines with new technology. PERC cell structures and n-type mono-Si materials are becoming more established. This means that project partners are faced with the task of preparing their next step towards production processes for high-efficiency and cost-effective solar cells. Project KosmoS will involve developing crystallisation and sawing processes for n-type mono-Si materials of the highest purity and solar cells with over 22% efficiency that can be interconnected in the conventional way to form modules. In technological terms, this should enable an evolutionary connection to the current PERC-/nPERT production processes. The overall goal of this is to reduce the LCOE by 10% as compared to standard solar cells.


The KosmoS project will be carried out in close cooperation with affiliated partners along the crystalline value chain from crystal to solar cells: PVA TePla, PV Crystalox Solar Silicon, Fraunhofer CSP, RCT Solutions and ISC Konstanz will be working together on the development of new systems and processes.

The pre-destined material for high-efficiency solar cells is float-zone silicon – thanks to the fact it has an oxygen concentration two orders of magnitude lower, an exceptionally low concentration of residual impurities and a very homogeneous resistance distribution. In combination with an n-type rear emitter cell concept, it results in potential efficiency of over 22% – when using production steps similar to the PERC production lines of today and a conventional modular construction.

The challenges are the crystallisation of bars with a diameter of 200 mm, the cost-effective supply of storage bars suitable for FZ, sawing the crystal with minimal cutting losses and the highest yields, and having a streamlined cell process that enables the advantages of the material to be exploited for financial benefit through a significant improvement in efficiency.