Integrating the Value Chain: The Impact of Silicon Quality on Cell Performance

Steeman, R.A.; Yong, Jeannie; Mjøs, Øyvind; Song, Adolphus

doi:10.1016/j.egypro.2012.02.003

Cited by 11 publications

(3 citation statements)

References 2 publications

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“…Although the rapid expansion in world production capacity have presently made the silicon prices drop, the long term expectations are still growing in PV energy demand and thereby significant growth in polysilicon consumption can be expected in the future Liu (2012), Steeman (2012) and Bernreuter (2012).…”

Section: Introductionmentioning

confidence: 99%

Production of Silicon from SiH4 in a Fluidized Bed, Operation and Results

Filtvedt

Mongstad

Holt

et al. 2013

International Journal of Chemical Reactor Engineering

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The photovoltaic industry has experienced a tremendous growth over the last years. The backbone of the technology has so far been elemental silicon. Silicon is the second most abundant element on the earth, but in order to be utilized for solar panels, it needs to be purified. This purification process is very energy intensive. Behind a finished solar module, up to 30% of the energy goes into purification depending on route, Cucchiella and D´Adamo (2012).Reducing the energy payback time of solar panels is important, and focus on silicon production is crucial, since this is one of the most energy intensive parts. The production of polysilicon involves production of metallurgical silicon from quartz and further processing into polysilicon. The most common route for the latter step is the Siemens process. In this process, chlorosilane is produced from chlorination of the metallurgical silicon. Subsequently, trichlorosilane is reduced in a decomposition process after some additional refining. The decomposition reactor itself is where the energy consumption becomes large.The silicon containing reactant starts to decompose at a temperature of typically 350 -480 °C depending on the process. However, in order to assure correct deposition, the deposition itself has to happen at temperatures as high as 1100°C for trichlorosilane, and about 650°C for monosilane. The layout of the Siemens process is simple. Electrical heating elements of silicon are distributed within a cooled dome. The heating elements are kept at typically 1100°C, while all other surfaces are kept at about 250°C. The process takes days and even weeks, depending on the process optimization, and the heat loss is therefore substantial.There is one other technology producing polysilicon to the market today, and this is the fluidized bed reactor. In a Fluidized Bed Reactor (FBR), the reactor vessel is filled with silicon particles. A gas is injected at the bottom of the reactor to fluidize the particles. Fluidizing the particles means the drag force on the individual particles is on the same scale as the weight of the particle. In this state, the bed of particles behaves like a liquid, and the flow of gas keeps the bed in continuous motion. The particles are heated to a temperature above the decomposition temperature and the reactant gas is inserted to the bed. Upon decomposition, the silicon deposit on the particles thus making them grow. After some dwell time, the particles have grown to a size suitable for extraction. The finished beads are then extracted, and new small seed particles are inserted to or produced within the bed.What complicates the picture is the decomposition of the reactant and how this influences growth. Challenges associated with FBR production of polysilicon involves dust (fines) production, unwanted depositions on surfaces other than the beads as well as inadequate quality due to porosity, amorphous inclusions and impurities.During the PhD project a state of the art fluidized bed has been designed, built and operated. This the...

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Section: Introductionmentioning

confidence: 99%

Production of Silicon from SiH4 in a Fluidized Bed, Operation and Results

Filtvedt

Mongstad

Holt

et al. 2013

International Journal of Chemical Reactor Engineering

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“…Although the exponential growth in world production capacity made the silicon prices drop dramatically, they are foreseen to become stable in the next years [2,3] and significant growth in polysilicon consumption is expected in the medium-long term [4,5]. As the production of silicon feedstock is responsible of about 25-33% of the energy cost of an installed silicon based solar cell module [6,7], the importance for polysilicon producers to reduce production costs is revealed [8].…”

Section: Introduction and Scopementioning

confidence: 99%

Deposition reactors for solar grade silicon: A comparative thermal analysis of a Siemens reactor and a fluidized bed reactor

Ramos

Filtvedt

Lindholm

et al. 2015

Journal of Crystal Growth

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Polysilicon production costs contribute approximately to 25-33% of the overall cost of the solar panels and a similar fraction of the total energy invested in their fabrication. Understanding the energy losses and the behaviour of process temperature is an essential requirement as one moves forward to design and build large scale polysilicon manufacturing plants. In this paper we present thermal models for two processes for poly production, viz., the Siemens process using trichlorosilane (TCS) as precursor and the fluid bed process using silane (monosilane, MS). We validate the models with some experimental measurements on prototype laboratory reactors relating the temperature profiles to product quality. A model sensitivity analysis is also performed, and the effects of some key parameters such as reactor wall emissivity, gas distributor temperature, etc., on temperature distribution and product quality are examined. The information presented in this paper is useful for further understanding of the strengths and weaknesses of both deposition technologies, and will help in optimal temperature profiling of these systems aiming at lowering production costs without compromising the solar cell quality.

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“…As all the forecasts indicate that the PV will continue its expansion, and siliconbased technology will remain its workhorse, a significant growth in polysilicon consumption is expected in the medium-long term [Steemana et al, 2012], [Bernreuter, 2012].…”

Section: Polysilicon and Solar Grade Siliconmentioning

confidence: 99%

Understanding and improving the chemical vapor deposition process for solar grade silicon production

Ramos¹

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This Doctoral Thesis comprises research on polysilicon deposition for photovoltaic (PV) applications through the chemical route: chemical vapor deposition (CVD) process. Lowering the energy consumption of the Siemens process is essential to achieve the two wider objectives for silicon-based PV technology: low production cost and low energy payback time. On the other hand, a valuable variation of this process considers the use of monosilane (MS) in a fluidized bed reactor (FBR); lower output material quality is obtained but it may fulfil the requirements for the PV industry. FBRs demand lower energy consumption than Siemens reactors but further research is necessary to address the actual challenges of these reactors. This work is centered in PV polysilicon (also known as solar grade silicon, SoG Si) CVD process from TCS -Siemens reactor-; but it also offers insights on the strengths and weaknesses of the FBR for SoG Si production.

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Integrating the Value Chain: The Impact of Silicon Quality on Cell Performance

Cited by 11 publications

References 2 publications

Production of Silicon from SiH4 in a Fluidized Bed, Operation and Results

Production of Silicon from SiH4 in a Fluidized Bed, Operation and Results

Deposition reactors for solar grade silicon: A comparative thermal analysis of a Siemens reactor and a fluidized bed reactor

Understanding and improving the chemical vapor deposition process for solar grade silicon production

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