• Slurry grit evolution

    In slurry-based wafering of silicon bricks using multi-wire saws, the slurry is subject to significant evolution with time as the grits become worn and the silicon kerf accumulates. A good understanding of this evolution would allow wafer producers to make better-informed decisions on when and how to replenish slurry during wafering. This paper summarizes certain important slurry properties and presents some experimental results regarding their evolution. Sampling the slurry at the front and rear of silicon bricks during wafering has allowed the effect of a single pass through the sawing channel to be studied. The wear on the slurry grit is interpreted in terms of identifying what portion of the particle-size distribution plays the most critical role in wafering, and how this critical region changes as the slurry ages. It is found that in a relatively fresh slurry, the particles around the median size and slightly larger are the most active, while particles more than a few μm below the median play only a small part. As the slurry ages, the active region of the particle-size distribution becomes narrower, and shifts towards larger particles even though there are fewer such particles available. This leads to less slurry–brick interaction and poorer material removal properties.

  • 3D multi-physics modelling of unidirectional solidification of mc-Si in an ingot furnace

    Unidirectional solidification of large Si ingots from the melt phase is currently one of the most important technologies for producing mc-Si for PV cells. Si ingot furnaces began from casting equipment, and have been improved by DSS (directional solidification system) or DSS-like methods. To improve PV cell efficiency and reduce costs, intensive development has focused on increasing a single ingot’s volume, reducing impurities and controlling the growth speed and temperature gradient. One of the latest developments of Si ingot furnaces is mono-like crystalline silicon growth using a seed preservation method and more accurate control. The Si ingot furnaces are optimized with precise control of temperature gradients and growth speed for the formation of a large unit of quasi-monocrystalline Si. This optimization can further improve a PV cell’s efficiency by at least 1%. In order to obtain fundamental knowledge about the key process steps that determine the growth and electrical quality of mc-Si via directional solidification in an ingot furnace, a combined modelling-measuring approach is essential. Moreover, a mathematical model of the Si ingot casting process can be used for model-based process control.

  • Market dynamics of materials supply for PV in China

  • Solar-grade silicon – is ‘Siemens’ the only answer?

  • Cz-Si wafers in solar cell production: Efficiency-limiting defects and material quality control

  • Diamond wire sawing: State of the art and perspectives

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  • Photovoltaics International 23rd Edition

    This issue of Photovoltaics International, our 23rd, offers key insights into some of the technologies that are ready to move from lab to fab in support of these goals. ISC Konstanz offer a glimpse of what the low-cost, high-efficiency solar cells of the future might look like. On page 35 the institute’s authors give an overview of what they call Konstanz’ “technology zoo”, encompassing their so-called BiSoN, PELICAN and ZEBRA cell concepts, all of which are aimed at increasing energy yield at the lowest possible cost.

  • Manufacturing The Solar Future: The 2013 Production Annual

    In the ever-changing global solar markets, cost reduction and measures to increase cell efficiencies are the key tools available to PV manufacturers to create new opportunities and drive your business to the next level. Manufacturing the Solar Future 2013 is the third in the Photovoltaics International PV Production Annual series, delivering the next instalment of in-depth technical manufacturing information on PV production processes designed to help you gain the competitive edge.

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