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SOLARAWARDS2011 SHOR TLISTED


Silicon Innovation Award


REC’s “fluidized bed reactor” (FBR) process


RECs proprietary Fluidized Bed Reactor (FBR) process represents the cutting edge technology in silicon production. After 15 years of R&D, REC has developed a process that produces silicon in a continuous process (vs. a batch process) and results in a ready-to- use output that requires no post- processing. The NextSi Granular Polysilicon, which is produced by the environmentally-conscious FBR process gives REC solar modules an industry leading payback time of one year, 20% less time than competing products.


Challenge


A major part of the energy consumption associated with producing solar cells is related to the purification of silicon. The “Fluidized Bed Reactor” (FBR) technology, used by REC for the silicon purification process, consumes significantly less energy for producing high purity silicon used for high performance solar products. Moreover, the FBR process lowers the cost of making solar products, whilst saving large amounts of electricity.


Problem Solved With the “Fluidized Bed Reactor (FBR) process, REC can produce solar-grade silicon, while using 80-90% less energy than the traditional Siemens method for converting silane gas to high purity silicon. Firstly, it does not waste energy by placing heated gas and silicon in contact with cold surfaces. Secondly, it produces more silicon per cubic meter of reactor space because the silicon crystals have a larger total surface area than the rods used in the Siemens process.


Thirdly, it is a continuous process rather than batch so there is less wasted downtime or setup. And finally, unlike other processes requiring the breaking of polysilicon rods, FBR granular is harvested in a ready to use form.


Noteworthy


RECs Fluidized Bed Reactor (FBR) process uses less energy to produce silicon than competing technologies, making it a more environmentally-sound choice. It also gives a payback time of one year, 20% less time than competing products. The company is also committed to reducing waste, using closed processes wherever possible and capturing 95-99% of the remaining production by-products and repurposing them. REC also uses only hydroelectric and wind power to power the process.


Innovation


RECs Fluidized Bed Reactor (FBR) process requires less energy to produce than other silicon production processes, giving REC silicon modules an industry- leading payback time of one year. The process produces silicon in a continuous process (vs. a batch process) and results in a ready-to-use output that requires no post-processing. RECs Fluidized Bed Reactor (FBR) process produces NextSigranular polysilicon, which is easier to handle. The FBR process is an efficient, continuous production cycle and has a ready-to-use output product, as opposed to existing solutions which are inefficient batch production and require additional post-production processing. Improved logistics automation (no manual breaking or packaging) reduces the potential for external contamination resulting in poorer product quality and performance. Granular polysilicon is packaged in bulk containers and because they round and can flow freely, it enables automated material transport and crucible loading. These factors combined amount to a significant reduction in the cost of solar ingot manufacturing compared to the traditional method further reducing the cost of solar energy. Moreover, there are a number of technological advantages to the RECs Fluidized Bed Reactor (FBR) process.


Customer Benefits


Overall, the RECs Fluidized Bed Reactor (FBR) process is an economically-sound choice because it maximizes productivity. Advantages of FBR-produced silicon include: Increased Process Efficiency maximizes crucible load, ability to top-off and/or recharge crucible, highly repeatable, controlled process, mitigates process problems, increases productivity Optimized logistics reduces amount of shipping and handling, increases


28 www.solar-pv-management.com I Issue VIII 2011


operational efficiency, High Automation Potential reduces handling, increases operational efficiency, increases productivity


SCHOTT Solar AG


Silicon Innovation The solar manufacturer from Mainz, Germany, SCHOTT Solar, has developed a new technique that will allow for high- performance multi crystalline solar cells to be manufactured on a large-scale industrial basis. The solar cells produced in an industrial environment achieve peak efficiency of above 18%. In combination with improved module technology, record efficiency of 17.6% was achieved on the surface of the aperture and confirmed independently by ESTI (European Solar Test Installation).


The innovative high-performance cells used in the champion module feature a front side that corresponds with the current standard in industrial manufacturing. The backside, on the other hand, has been passivated by using a combination of different dielectric layers that feature local contacts, better known in the industry as the PERC structure. Commercially available multi crystalline silicon wafers from its subsidiary SCHOTT Solar Wafer GmbH in thicknesses of 180- 200 µm are the starting material. This made it possible for the researchers who work for the Mainz-based company to produce cells in the standard size 156x156mm2 that offer efficiency of more than 18% in pilot production.


Conventional silkscreen printing technology was then used to create the contacts. According to the solar manufacturer, this technique successfully links new manufacturing steps with a mature and cost-efficient production sequence.


New approaches to increasing performance were used during manufacturing of these modules to reduce both optical and electrical losses while the solar cell was being turned into a module. Confirmed efficiency of 17.6 % that the world that has never seen before


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