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Development and demonstration of foil-based lamination and interconnection concept

To develop and demonstrate prototype production equipment for an economically viable module assembly line, which is suitable for high handling yield and high throughput of thin and high-efficiency solar cells, and which is ready to be put on the market at project-end.

This project aims to develop and demonstrate prototype production equipment for an economically viable module assembly line, which is suitable for high handling yield and high throughput of thin and high-efficiency solar cells, and which is ready to be put on the market at project-end. The integral assembly line prototype must be able to realise the following targets, to become economically interesting for customers: a. High throughput: 1 cell per second, modules of 6x10 cells. b. Large and thin solar cells: 156x156 mm2 and 120 micrometre thick. c. High handling yield: 99.5%. d. Costs of ownership: decrease by 50% compared to current module assembly lines. e. Operation down time: less than 10%, when running 24 hours a day, 7 days a week. To make the step from the current pilot line to the envisioned 150MWp assembly line, the two following major technical bottlenecks need to be resolved and demonstrated as a prototype at a launching customer: 1. Interconnection of solar cells The interconnection of the solar cells in the modules that the FLAMENCO consortium envisions is a step-change in the PV (Photovoltaic) industry. This innovative interconnection technology is established by means of conductive adhesive. This approach requires several new supporting technologies including back-sheet foils with electrically conductive layers and interconnection printing technology. This conductive adhesive interconnection approach has been tested with highly promising results at ECN; however, this proof of principle needs to be developed into a commercially viable and implementable assembly station. For this the following bottlenecks need to be researched and solved: 1a. Foils The interconnection foil for the FLAMENCO assembly line needs to contain conducting layer(s) to deliver the electricity generated from the solar cells. The challenge is to develop a foil, with good conductivity, made from abundantly available materials at low costs (approximately 15 euro / m2). For this, the consortium will research the suitability of using aluminium, or aluminium-copper alloy to function as the conductive layers, and compare them to the expensive copper that was used in the first trials at ECN. ECN and HANITA will design, develop and test different types of interconnection foils, on the pilot line at ECN. 1b. Inter Layer Dielectric (ILD) The rear-side of the MWT (Megawatt Thermal) solar cells contains emitter contact spots among the base terminals and the rear-side metallisation. In order to avoid short-circuiting, these contact spots must be isolated from these base terminals and lines by means of Inter Layer Dielectric (ILD) on the interconnection foils. ECN, in collaboration with SUNCHEM, will develop the ILD masking material. 1c. Interconnection printing The conductive adhesive is laid-up on the conductive foil by means of stencil printing technology on the module assembly line. For the full-size 6x10 module there are 60 MWT cells with 31 interconnection contact points. This means one conductive foil will have in total 1,860 contact points onto which the conductive adhesive needs to be printed. Moreover, the openings on the screen will get clogged up over the usage period with residues and unused conductive adhesive and thus the screen needs to be cleaned at regular intervals to achieve good and reproducible print. EUROTRON will need to evaluate and characterise the stencil printing technology to lay-up the conductive adhesive for cell-to-foil interconnection. In addition, cleaning and maintenance protocols need to be developed. 1d. Interconnection foil feeding The supplied interconnection foil needs to be fed into the assembly line. EUROTRON needs to develop concepts for handling, feeding and laying-up of the interconnection foil in the module assembly line. 2. Module encapsulation 2a. Encapsulant material The encapsulant needs to have good adhesion to the solar cells and conductive back-sheet foils. In addition, the encapsulant should not act as a moisture trap and if possible, has minimal moisture propensity characteristics. ECN will evaluate module encapsulants' (EVA and/or alternatives) applicability to the MWT modules, investigate the optimal thickness, integration with the interconnection foil, adhesion properties and curing profile. The expected result is an encapsulant to be used on a MWT module assembly line that will meet solar module product reliability requirements as set out in the IEC61215 / 61730 standard. 2b. Encapsulant feeding system It is expected that the encapsulant material will be produced and supplied by suppliers in the form of rolls. It is therefore necessary to have a feeding system of the encapsulant that will transform the material from its roll form into a sheet form ready to be placed by the lay-up station. EUROTRON needs to develop concepts for handling, such as feeding (unwinding and slitting), perforation, lay-up and waste management of the encapsulant on the module assembly line.
Acronym: 
FLAMENCO
Project ID: 
5 351
Start date: 
01-09-2009
Project Duration: 
30months
Project costs: 
3 360 000.00€
Technological Area: 
Photovoltaics
Market Area: 
Photovoltaic solar

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