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Jayakrishnan R.,P.A. College | Gandhi S.,Indian Institute of Technology Bombay | Suratkar P.,TATA BP Solar India Ltd
Materials Science in Semiconductor Processing | Year: 2011

Among the key parameters that ultimately control the performance of a solar cell, the Minority carrier lifetime plays the most crucial role. In the process chain involved in conversion of a wafer to a solar cell, each process contributes to change in the carrier lifetime. Hence performance of a particular process can be quantified based on the measure of carrier lifetime before and after the specific process. In an industrial production line, measure of carrier lifetime can be used for real time diagnosis. This paper deals with how to model the overall performance of a production line based on minority carrier lifetime of the wafers used to fabricate the cell. We have shown in this paper that the processing of wafers which were segregated based on their minority carrier lifetime results in increase in yield of the production line. Segregated processing also resulted in improvement of electrical performance of the batch processed solar cells. © 2011 Elsevier Ltd. All rights reserved.


Saravanan S.,TATA BP Solar India Ltd | Mahadevan M.,Institute of Chemical Technology | Mahadevan M.,University of Maryland University College | Suratkar P.,TATA BP Solar India Ltd | Gijo E.V.,Indian Statistical Institute
International Journal of Sustainable Energy | Year: 2012

Crystalline silicon solar cell technology continues to be dominant in the photovoltaic (PV) technology due to its novel process flow and the clear understanding of the material. Being a mature material-based technology; on the one hand, it has quite a few opportunities for improvement, on the other hand, the expansion of solar energy should depend on this technology. Due to increase in the global energy consumption and high competition level in the market, it has become necessary to show significant improvement in the performance of the present process/product. The demand for high efficiency solar cells at low costs with shorter cycle times forced the manufacturing industries to improve their processes by applying systematic methodologies such as Six Sigma. This paper illustrates the importance of anti-reflective coatings (ARCs) on the silicon solar cell processes and the successful implementation of Six Sigma to improve the efficiency of the silicon solar cells. The different phases of the Six Sigma DMAIC approach applied to the process and the results are interpreted. © 2012 Copyright Taylor and Francis Group, LLC.


Kumar D.,TATA BP Solar India Ltd | Saravanan S.,TATA BP Solar India Ltd | Suratkar P.,TATA BP Solar India Ltd
Journal of Renewable and Sustainable Energy | Year: 2012

Phosphorous (P) diffusion is the most important and crucial process in the fabrication of silicon (Si) solar cells from p-type Si substrates. P-diffusion using phosphorous-oxycholoride (POCl 3) as a precursor in a tube furnace had shown the best cell performance over the belt diffusion because of uniform dopant concentration all over the Si surface and gettering of metallic impurities present in the substrate. The emitter formation by using POCl 3 is a complex and advanced process which provides the gettering and forming the unwanted dead layer on the front surface due to inactive phosphorous. Along with temperature, the ambient conditions during the diffusion process, such as gas flow rates and their composition, flow kinetics also have an impact on the emitter properties. In the present paper, the impact of oxygen (O 2) flow during the diffusion process on the emitter formation and the solar cell performance were studied. It has been found that, the presence of oxygen during the diffusion process influences the concentration of inactive phosphorous over the surface and the gettering process as well. The optimized oxygen flow shows an improvement in the effective minority carrier lifetime of ∼24 μs after diffusion and an absolute efficiency gain of 0.2 at pilot production. © 2012 American Institute of Physics.


Kumar D.,TATA BP Solar India Ltd | Saravanan S.,TATA BP Solar India Ltd | Suratkar P.,TATA BP Solar India Ltd
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2011

Phosphorous (P) diffusion is the most important and crucial process in the fabrication of silicon (Si) solar cells. P-diffusion using POCl 3 in a tube furnace reveals the best cell performance because of uniform dopant concentration over the Si surface and gettering of impurities in the substrate. The emitter formation by P-diffusion using POCl 3 diffusion source is a complex and advanced process which provides the gettering and forming the unwanted dead layer on the front surface due to inactive phosphorous. Along with temperature, the ambient conditions during the diffusion process, such as gas flow rates and their composition, flow kinetics also have an impact in the emitter properties. In the present paper, the impact of oxygen (O 2) flow during the diffusion process has been studied. It has been found that, the presence of oxygen during the diffusion process influences the concentration of inactive phosphorous over the surface and the gettering process as well. The optimized flow of oxygen shows, an improvement in lifetime of ∼ 24 μsec and an absolute efficiency gain of ∼0.3%. © 2011 IEEE.


Dasari S.M.,TATA BP Solar India Ltd | Srivastav P.,TATA BP Solar India Ltd | Shaw R.,TATA BP Solar India Ltd | Saravanan S.,TATA BP Solar India Ltd | Suratkar P.,TATA BP Solar India Ltd
Renewable Energy | Year: 2013

Conventional silicon based photovoltaic industries, which convert silicon cells to modules attracted the attention of the researchers due to the cell to module conversion power losses. The conversion power losses are due to the various parameters such as shadow effect, inherent properties of the solar cells, properties of the materials used for fabricating the module etc. Among them, the inherent properties of the solar cells play a major role in module power. The electrical properties of the solar cell such as series resistance and fill factor drive the conversion power losses in the module. By increasing the number of contact points, the losses will be reduced. In this work it is found that by introducing an extra bus bar in metallization pattern leads to a great reduction in conversion losses. The fill factor gain is observed in three bus bar based modules compared to two bus bar based modules because of the contact points per cell increase which lead to low resistance losses. It is obvious that the power gain in three bus bar modules dominates shadowing loss due to an additional bus bar. A systematic approach on minimising the cell to module conversion loss by optimizing the front contact bus bar width has been studied. It is important that beyond the optimum value of bus bar numbers and its width the shadowing loss will dominate over the gain. © 2012 Elsevier Ltd.

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