Manufacturing technology for ribbon silicon (EFG) wafers and solar cells

Schmidt, Wolfgang A.; Woesten, B.; Kalejs, J.P.

doi:10.1002/pip.411

Cited by 29 publications

(14 citation statements)

References 4 publications

(5 reference statements)

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“…Record efficiencies for EFG and SR cells in the range of 18% are comparable to the best cells fabricated from multi-crystalline wafers from ingots, when lab-type processes of the same complexity are used. The same is true for industrial-type processing, with record efficiencies between 15 and 16% and mean values around 15% for EFG solar cells in production [96], slightly lower as for solar cells from ingot based wafers. From these data, it can be concluded that solar cells from EFG or SR wafers have a significant advantage concerning cost per W p , provided a comparable yield is achieved.…”

Section: Discussionsupporting

confidence: 56%

New Crystalline Si Ribbon Materials for Photovoltaics

Hahn¹,

Schönecker²,

Gutjahr³

2009

Advances in Materials Research

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Abstract. The objective of this chapter is to review, for photovoltaic application, the current status of crystalline silicon ribbon technologies as an alternative to wafers originating from ingots. Increased wafer demand, the current silicon feedstock shortage and the need of a substantial module cost reduction are the main issues that must be faced in the booming photovoltaic market. Ribbon technologies make excellent use of the silicon, as wafers are crystallised directly from the melt in the desired thickness and no kerf losses occur. Therefore, they offer a high potential to significantly reduce photovoltaic electricity costs when compared to wafers cut from ingots. Nevertheless, the defect structure present in the ribbon silicon wafers can limit material quality and cell efficiency. Ribbon GrowthTo provide an answer to the rapidly growing demand for cheap and easily available solar electricity, the photovoltaic industry is looking for more cost efficient and faster manufacturing processes for all steps of the value chain from silicon feedstock to crystallisation and wafering, cell processing and finally module fabrication. Silicon ribbons, as an alternative to silicon wafers that have been crystallised in the form of ingots and then cut into wafers, have, due to their higher silicon usage and potential for high production speed, significant advantages with respect to cost and throughput. However, a more complex technology and different wafer properties that often result in slightly lower conversion efficiencies are obstacles to be overcome.In principle, all ribbon processes have the characteristics that almost all silicon supplied into the process is converted into wafers. There is also no wafer cutting from a block, although in dependence upon the production method separation of larger sheets into wafers may be needed. Depending upon the type of crystallisation, silicon ribbon growth processes are either relatively slow processes, which can be run on rather low-cost equipment or high-speed processes operated with rather complex machinery.

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Section: Discussionsupporting

confidence: 56%

New Crystalline Si Ribbon Materials for Photovoltaics

Hahn¹,

Schönecker²,

Gutjahr³

2009

Advances in Materials Research

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“…Large area solar cells processed according to an industrial-type fabrication scheme show significantly lower efficiencies. Record values of 15.3% for EFG material (10 × 10 cm 2 [171]) and 15.6% for SR material (8 × 10 cm 2 [172]) have been reported. One significant limitation, apart from higher shadowing losses and lower sheet resistivity, is the lack of an efficient surface texture for EFG and SR materials.…”

Section: Efg and Sr Solar Cellsmentioning

confidence: 99%

New crystalline silicon ribbon materials for photovoltaics

Hahn

Schönecker

2004

J. Phys.: Condens. Matter

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The objective of this article is to review, in relation to photovoltaic applications, the current status of crystalline silicon ribbon technologies as an alternative to technologies based on wafers originating from ingots. Increased wafer demand, the foreseeable silicon feedstock shortage, and the need for a substantial module cost reduction are the main issues that must be faced in the booming photovoltaic market. Ribbon technologies make excellent use of silicon, as wafers are crystallized directly from the melt at the desired thickness and no kerf losses occur. Therefore, they offer a high potential for significantly reducing photovoltaic electricity costs as compared to technology based on wafers cut from ingots. However, the defect structure present in the ribbon silicon wafers can limit material quality and cell efficiency. We will review the most successful of the ribbon techniques already used in large scale production or currently in the pilot demonstration phase, with special emphasis on the defects incorporated during crystal growth. Because of the inhomogeneous distribution of defects, mapped characterization techniques have to be applied. Al and P gettering studies give an insight into the complex interaction of defects in the multicrystalline materials as the gettering efficiency is influenced by the state of the chemical bonding of the metal atoms. The most important technique for improvement of carrier lifetimes is hydrogenation, whose kinetics are strongly influenced by oxygen and carbon concentrations present in the material. The best cell efficiencies for laboratory-type (17%-18%; cell area: 4 cm 2) as well as industrial-type (15%-16%; cell area: 80 cm 2) ribbon silicon solar cells are in the same range as for standard wafers cut from ingots. A substantial cost reduction therefore seems achievable, although the most promising techniques need to be improved.

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“…An interesting option in Si solar cell manufacturing is the growth of ribbons [62,63]. Ribbons do not require the expensive sawing process.…”

Section: Crystalline Silicon Progress and Challengesmentioning

confidence: 99%