Microcrack Detection in Crystalline Silicon Solar Cells

Both mono- and multi-crystalline silicon wafers and solar cells occasionally contain microcracks that are difficult or impossible to see with the human eye or even with a vision system. These cracks ¿ which are due to mechanical and thermal stresses during cell fabrication and module assembly, as well as to diurnal thermal cycling after installation ¿ can propagate, resulting in cell breakage and power loss. This project will develop a microcrack detection technique that can be used as an in-process diagnostic method for identifying defective crystalline silicon wafers or solar cells in a production line. In Phase I, the feasibility of the detection technique will be demonstrated. Then, Phase I will design, build, and test a prototype automated microcrack detection system. Commercial Applications and other Benefits as described by the awardee: Solar cell and module manufacturers typically use manual visual inspection to find microcracked wafers and cells during production. This process not only is labor intensive but also is not completely effective in finding microcracks. An automated system for detecting and segregating wafers and cells with microcracks would reduce the labor requirements for inspections and rework, increase production yields, and improve module reliability and lifetime.