For the optimization of silicon cell manufacturing processes with respect to a reduction of breakage losses an i ntegral concept was developed and applied in industrial manufactu­ring lines. The concept consists on a combination of different approaches.

Measurements of the cell strength after specific manufacturing processes reveal, whether these processes induce or reduce damaging. The damage and crack formation and evolution history is investigated by fractographic and microscopic inspections of original cells broken during manufacturing. Fracture relevant processes are analysed by experi­ments and by numerical modelling in order to determine the acting mechanical or thermo­mechanical loadings. Numerical simulations by means of finite element analyses help to optimise the processes, because the influencing process parameters can be varied in the computer. Testing methods such as acoustic techniques or proof-tests are applied for the early detection and elimination of cells which are not able to survive further processing.

By a combination of the results of these approaches the causes of breakage losses can be localised, analysed and deleted.

[1] Beinert, J., Kordisch, H., Kleer G.: Studies on Fracture and Strength of Photovoltaic Silicon Wafers, World Renewable Energy Congress VII (WREC 2002), 2002, Cologne, Germany, Pergamon, 2002