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FACILITYMANAGEMENT


the cost reduction for BIPV at LCOE stage is not so simple: As a rule the BIPV product must be manufactured to be more stable and additional add-on parts must be offered so that the structure meets aesthetic demands. On the other hand, the roof cladding usually needed is no longer required with BIPV roofing elements. If BIPV elements are included for roof claddings and facades for new buildings even now, then considerable savings in the system costs can be expected.


Manufacturing Execution System The examples given have shown in parts how costs can be reduced with modified processes. The processes are also merging more and more and need to be matched to one another. In the manufacture of (standard) solar cells 6 or more steps are required in succession typically: texturing of the surface, doping, diffusion, removal of the oxide, antireflex coating, metallization and firing. The cell efficiency is measured and every step has a direct or indirect influence on the cell’s performance. Some steps influence each other, like diffusion and the material quality (gettering), texturing and diffusion (surface cleaning) or the antireflex coating and firing (hydrogen passivation). Machines produce data that do not reveal relationships until they are studied.


A painstaking recording of the data is necessary. Detailed analysis based on SPC (Statistical process control) delivered by PQMS system (process and quality management system) takes this approach into account. The PQMS automatically offers two more potential cost reductions: it provides the basis for running the FAB even more efficiently and purposefully and it also shortens the production optimisation loop [5].


Conclusion


The production processes in the solar industry still have great potential for optimisation; this can be achieved by new processes, new tools based on this processes, new materials and new designs of products. The requirements are very high however: hardly any other mass product is expected to last far beyond 20 years while simultaneously not allowing performance to drop below 80%. Other industries have shown how to manufacture complex products with increasingly fewer amounts of materials and energy for lower costs.


Chart 3.


Comparison between 3S Standard and high performance three chamber process


This article shows usable potential in the areas of wafers of 3%, cell of 2%, module of 0.4%, i.e. more than 5% of the LCOE. If the increase in durability from 20 to 30 years is also looked at, the LCOE costs per kWh drop by 30%.


If the costs of silicon to module manufacture were to be reduced by 5% every two years, this means a costs reduction of 20% in five years. In the thin film area with lower efficiencies, module manufacturing costs of less than 0.8 USD/Wp are possible.


The need remains for an overall study of the LCOE costs. For example, IV curves need to be measured sensitively for insolation (irradiation) strength and assessed with a standardised coefficient (like the European coefficient when assessing inverters). There is no need for an IV curve with an MPP point, but a kWh curve with insolation/m2 as a variable makes more sense.


Secondly, the assessment of the maximum period of use of a solar system is necessary. In view of the fact that the durability of a PV system has a variator of 95%, standards need to be deduced in order to measure the period of use of a solar module. And this means the periods of use beyond 30 years.


To technically achieve such periods of use, the materials, processes and intermediate products must be manufactured to a high level with the smallest of variances (six sigma level). The tool for this is the PQMS; this data can be used as the basis for SPC analyses.


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REFERENCES: [1] Verband Deutscher Maschinen- und Anlagenbau e.V. [2] Semiconductor materials and equipment international [3] U. Michel, A. Maiocchi, RFM Lange, InterPV Asia, March 2010 [4] Y. Luo, R. F. M. Lange; Significant reduction of the lamination cycle time by using a novel lamination concept combined with a systematic design of experiments approach; PVSEC 25th proceedings (2010) [5] S. Leu, A fully-integrated solar factory – requirements for achieving grid parity, edition 1, Photovoltaics International, London, United Kingdom The publishers would like to thank the IPVEA for their assistance and permission


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www.solar-pv-management.com Issue II 2011


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