DEK Solar

Weymouth, United Kingdom

DEK Solar

Weymouth, United Kingdom

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Wong J.,Solar Energy Research Institute of Singapore | Shanmugam V.,Solar Energy Research Institute of Singapore | Shanmugam V.,National University of Singapore | Cunnusamy J.,DEK Solar | And 7 more authors.
Progress in Photovoltaics: Research and Applications | Year: 2015

While it is well known that the typical printed silver fingers on a silicon solar cell have profile striations, bottle-necks, and line breaks, the impact of these imperfections have not been assessed in calculations of front grid related power losses. This study uses detailed finite element modeling to show that when the realistic effects of non-uniform line conductance is accounted for; the simulated cell efficiency can be significantly lower than under the assumption of uniform lines, becoming closer to measured trends. The study also explores the incorporation of additional interconnecting fingers to the parallel grid finger in the H pattern, concluding that they are typically of no benefit to improving the cell efficiency. As an auxiliary observation, it was found that the efficiency calculated by simple ohmic power loss formulae is typically underestimated by 0.1-0.2% absolute, a margin that should be accounted for in cell optimization and analysis. Copyright © 2015 John Wiley & Sons, Ltd.


Shanmugam V.,Solar Energy Research Institute of Singapore | Wong J.,Solar Energy Research Institute of Singapore | Peters I.M.,Massachusetts Institute of Technology | Cunnusamy J.,DEK Solar | And 6 more authors.
IEEE Journal of Photovoltaics | Year: 2015

Primary challenges to fine-line silver printing for solar cells are achieving high aspect ratios and uniform lines with a low level of striations. This paper compares two high-throughput printing technologies, namely, printing by screens versus stencils. A statistical method is introduced to evaluate the quality of the printed front grid based on the distributions of printed metal line profiles, line segment conductance, overall electroluminescence (EL) pattern, and solar cell light current-voltage (I-V) characteristics. The model distribution, combined with finite-element modeling to predict realistic cell-level voltage variations, adequately describes all four kinds of characteristics. It predicts well the diverging performance of screen- and stencil-printed solar cells as the line width becomes less than 50 μm. Experimentally, the highest batch average efficiency of 18.8% was achieved on 156 mm × 156 mm p-type monocrystalline silicon solar cells printed with stencils having 30-μm line openings, using only 78 mg of silver paste per cell. © 2011-2012 IEEE.


Hannebauer H.,Institute for Solar Energy Research Hamelin | Dullweber T.,Institute for Solar Energy Research Hamelin | Falcon T.,DEK Solar | Chen X.,DEK Solar | And 2 more authors.
Energy Procedia | Year: 2013

We investigate and compare three different fine line printing techniques for the silver front side metallization of industrial-type silicon solar cells: single print, dual print and print-on-print. We obtain finger heights of 5.6 μm for single print, 9.5 μm for dual print and 15.1 μm for print-on-print as well as finger width between 46.2 μm and 61.3 μm. We process PERC solar cells with dual print and print-on-print. For the dual print, we test two different bus bar designs, a standard rectangular shaped bus bar and a segmented bus bar. The resulting PERC solar cells achieve conversion efficiencies of 19.8% for dual print and print-on-print. The dual print with segmented bus bar design reduces the Ag paste consumption to 67.7 mg, measured after printing prior to drying. To our knowledge, this is the lowest front side Ag paste consumption that has been reported so far. Additionally, we model optimum Ag finger width in dependence of electrical and geometrical parameters. We find that even when assuming very optimistic parameters, the optimum finger width of 26 μm is just a factor of two lower compared to the state of the art technology today. © 2013 The Authors.


Hannebauer H.,Institute for Solar Energy Research Hamelin | Dullweber T.,Institute for Solar Energy Research Hamelin | Falcon T.,DEK Solar | Brendel R.,Institute for Solar Energy Research Hamelin | Brendel R.,Leibniz University of Hanover
Energy Procedia | Year: 2013

In this paper, we investigate and compare three different fine line printing techniques for the silver front side metallization of industrial-type silicon solar cells: single print, dual print and print-on-print. We produce solar cells using the same screen or stencil aperture of 40 μm and about 92 fingers and obtain finger widths below 60 μm for all three approaches. The print-on-print process achieves the highest finger heights of 20 μm after firing but with quite strong finger height variation. In contrast, the dual printed fingers have a very flat surface with a finger height of 14.5 μm which leads to the highest cross-section area of 530 μm2 of the three techniques. The single print shows the lowest cross-section area of 390 μm2 due to the lowest average finger height. The measured finger line resistance correlates with the finger cross-section area. The dual print allows us to use a non-firing through bus bar paste which increases the V oc by 2 mV and hence achieves the highest efficiency of 19.1% using full-area Al-BSF cells. Due to an optimized bus bar screen print in combination with only 30 μm finger aperture, the dual print has the lowest Ag paste consumption of only 75 mg/wafer, one of the lowest Ag paste consumption that has been reported so far. A first batch of PERC solar cells with dual-printed Ag front contacts shows efficiencies up to 19.6%. © 2013 The Authors.


Hannebauer H.,Institute for Solar Energy Research Hamelin | Dullweber T.,Institute for Solar Energy Research Hamelin | Baumann U.,Institute for Solar Energy Research Hamelin | Falcon T.,DEK Solar | And 2 more authors.
Physica Status Solidi - Rapid Research Letters | Year: 2014

We evaluate industrial-type PERC solar cells applying a 5 busbar front grid and fineline-printed Ag fingers. We obtain finger widths down to 46 μm when using a stencil with 40 μm opening for the finger print, whereas the busbar is printed in a separate printing step with a different Ag paste (dual print). This compares to finger widths of 62 μm to 66 μm when applying print-on-print. The 5 busbar front grid with the best dual print process reduces the shadowing loss of the front grid to 4.0% compared to 5.8% for a conventional 3 busbar front grid printed with print-on-print. The 1.8% reduction in shadowing loss results in equal parts from the reduced finger width with dual print as well as from a reduced total busbar width of the 5 busbar design. The resulting PERC solar cells with 5 busbars demonstrate independently confirmed conversion efficiencies of 21.2% compared to 20.6% efficiency of the 3 busbar PERC solar cell. The increased conversion efficiency is primarily due to an increased short-circuit current resulting from the reduced shadowing loss. To our knowledge, 21.2% conversion efficiency is the highest value reported so far for industry typical silicon solar cells with printed metal front and rear contacts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Falcon T.,DEK Solar | Clasper S.,DEK Solar
EMPC-2011 - 18th European Microelectronics and Packaging Conference, Proceedings | Year: 2011

One of the principal drivers for the continuing miniaturisation of frontside conductors on silicon solar cells is the trend toward higher emitter sheet resistances. This trend is apparent both in mainstream cell production, and with the introduction of selective emitter technologies. High R sheet emitters make more efficient use of the blue end of the light spectrum, thereby enhancing cell efficiency. However, this benefit comes with the downside that the higher R sheet emitter impedes the flow of electrons through the semi conducting silicon, and therefore reduces current collection. Using a greater number of finer conductors with reduced conductor spacing can mitigate these resistance losses with no additional shadowing loss, thereby acting as an enabler for high Rsheet emitter technologies. With today's mainstream cell manufacturers printing lines below 100m wide, the sub 50μm printed line becomes the next logical milestone in the miniaturisation of frontside conductor geometries. This paper will describe the path to that milestone and beyond. © 2011 IMAPS.

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