Crystal Solar has a unique process of fabricating monocrystalline silicon wafers using an epitaxial deposition process that leads to high-quality kerfless wafers. In addition, the Epi deposition process allows Crystal Solar to deposit built-in junctions and surface fields in the wafers, which reduces downstream cost-in-cell processing. The project focuses on improving the base substrate reuses and process yield to lower the cost of epitaxial wafers through automation of the pilot process line. Additionally, high-efficiency cells will be fabricated to demonstrate the readiness of the epitaxial substrate with traditional solar cell processing.
The project team will demonstrate the repeatability of batch processing for porous silicon anodic etching with an optimized processing recipe and developed process control. They will include more etching tanks and modify the software correspondingly while increasing the throughput. They will also demonstrate a new method for edge release to improve the substrate yield during reuse using a laser with a different wavelength. It will reduce the damage in substrates to the minimum and increase the yield of substrate reuse.
This project will lower the cost epitaxial wafers and increase the performance of the cells. It extends conventional passivated emitter rear contact cell technology to have efficiencies well over 23%, which will enable rapid market acceptance of the epitaxial wafer approach and accelerated transition to high volume manufacturing.