By Felix Kaule, Fraunhofer Center for Silicon Photovoltaics CSP, Halle (Saale); Marcus Oswald, Fraunhofer Center for Silicon Photovoltaics CSP, Halle (Saale); Ringo Koepge, Fraunhofer Center for Silicon Photovoltaics CSP, Halle (Saale); Carola Klute, Fraunhofer Center for Silicon Photovoltaics CSP, Halle (Saale); Stephan Schoenfelder, Fraunhofer Center for Silicon Photovoltaics CSP, Halle (Saale); Leipzig University of Applied Science, Germany
The mechanical strength of monocrystalline and multicrystalline silicon wafers is mainly dictated by the cracks induced during the wire-sawing process. Different sawing technologies, such as diamond-wire- or slurry-based processes, lead to different strength behaviours of as-cut wafers. Furthermore, the strength is strongly influenced by texturization, and at this stage can be interpreted as the basic strength of a solar cell. The metallization and firing processes determine the final strength and reliability of a solar cell, with the metallization contacts being the root cause of breakage of solar cells, depending on the particular cell concept. This paper gives a comprehensive overview of the typical ranges of strength for as-cut wafers, textured wafers and solar cells, for the two different sawing technologies. Around 100 batches with 4,253 samples were evaluated in the study.
