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Accelerated development and prototyping of nano-technology-based high-efficiency thin-film silicon solar modules

Final Report Summary - FAST TRACK (Accelerated development and prototyping of nano-technology-based high-efficiency thin-film silicon solar modules)

Executive Summary:
The Fast Track project aimed to reduce the production costs of thin-film silicon modules by developing and implementing novel nano-techology based add-ons and add-ins. After three years of constructive collaboration between industrial and academic partners, this goal was reached. This document describes the main achievements of Fast Track.

Management of the consortium.
The coordinator and project manager have continuously taken care of the composition of the consortium. All planed an unplanned vacancies were effieciently filled up by suitable partners that were fully capable and equipped to perform the work. Alle technical deliverables were delivered in time and the progress has been carefully watched, discussed and planned according to the defined milesones in monthly conference calls of the executive board, general assemblies each 6 months and numereous WP conference calls and meetings at conferences. The results of Fast Track were disseminated in 70 scientific publications, the project website www.fast-track.eu and newsletters.

Collaboration.
The academic partners and industrial partnes have cooperated very constructively in an open admosphere in which the competitiveness between partners was hardly noticible. Extensive discussions during project meetings, visits between partners and personnel exchange have deepend the understanding of each others processes and boundary conditions, due to which pragmatic and creative solotions were found to the numerious practical challenges that occur when 20 partners work together on one product. Between the partners, alliances have originated that will continue until after the life time of Fast Track.

Technical results.
Thanks to the implementation of newly developed nano-technology based add-ons and add-ins, the consortium has delivered world-leading cell efficiency results: a record stabilized efficiency of 12.6% was obtained for an a-Si:H/nc-Si:H tandem device. Based on these developments, selected processes were transferred to the production lines of the end users. On large-areas this has led to efficiencies of 11.5%.
It should be noted that the aims efficiency aims (14% cell effieciency and 12% modules effiecienc) that were defined before the beginning of the project in order to reach the reduction of production costs below € 0,50 have not bee completely reached. On the other hand, due to the smart choice and the efficient implementation of the implemented technologies, the cost aim was reached in spite of it. Moreover, the consortoim delivers detailed roadmaps based on solid data and verified models to reach the 14% and 12%, repectively.
Large-area demonstrators of flexible-and glass modules in which the novel nanotechnologies were implemented and of the nano-imprinted antireflex foil have been demonstrated and out-door measured during the last general assembly.
The consortium leaves behind a number of compatible processes that partly can be also applied in different PV technologies.

Impact
The project results and the achievement of the cost goal and the perspective to reach the cost level of €0,40 for a 500 MWp factory have brought the end-users in a more competitive position. The markets for PV plants and PV roofs are expected to quadrupole in the next 5 years. These segments are expected to be the main market for glass and flexible solar panels, respectively. Thanks to the Fast Track results, the carbon footprint of TF-Si modules has decreased with 25-30%.

Project Context and Objectives:
Starting situation of Fast Track
The Fast Track consortium was constituted in 2010 and the DoW was written in 2011, in a period in which the industrialization of TF-Si PV had seen enormous acceleration. In these years, the first industrialization issues were solved and several companies demonstrated 10% stable modules (> 1 m²). The major “bricks” for efficient production were put in place. For reasons of competitiveness, more complex TF-Si based devices, i.e. multijunction devices, allowing for higher efficiency, needed to be industrialized. The concept of higher efficiency devices had been developed in different research labs. Multi-junction devices have a high degree of complexity, in which the substrate geometry and each layer have an impact on the device properties.
There were two main technology “families” that were based on devices developed on different TCO and PECVD concepts: the Jülich-AMAT approach and the EPFL-Oerlikon approach. Due to the fact that there was only little communication between these two “families”, the community believed that their individual technology optimizations would lead to local optimal conditions, in contrast to the global optimal conditions that would be found if the best of both technologies would be combined. Therefore, this project focused on bringing the next-generation technology to the market, using newly developed state-of-the art knowledge to solve the complex puzzle of achieving at the same time strong light in-coupling (high current) and good electrical properties (open-circuit voltage and fill factor).

Consortium of Fast Track
Fast Track has a multi-facetted consortium, whose members are established expert centers in their respective fields, covering practically all aspects that interact and determine or influence the efficiency of micromorph photovoltaics, and its transferability to industrial applications. Their cross-cutting areas and technologies extend over processes, modelling and design.
The Fast Track consortium has underwent significant changes in the course of the project. For a detailed overview, we refer to Appendix 3 “overview of versions” of the most recent DoW (October 2014). A summary of the developments is given here in this section.
Four partners have left the consortium during the project due to internal changes of focus or cooperation strategy: partner 13 (Malibu) in month 6, partner 14 (Euroglas) in month 12, partner 9 (Utrecht University) in month 13, partner 12 (Oerlikon Solar, later TEL Solar) in month 16. Two others were forced to leave the consortium due to insolvencies: partner 20 (OMT) in month 19, and partner 22 (Inventux) in month 26.
The insolvencies are attributed to the harsh PV market situation that occurred during the life time of Fast Track. The changes of strategy at Oerlikon Solar is attributed to the fact that the activities were taken over in the course of the project by a Japanese mother company (TEL) with a less open cooperation strategy.
At the same time, reacting on the changes described above, the Fast Track consortium has always found replacing partners to perform the tasks of the leaving partners, in almost all cases by finding a replacing partner and in the only other case (the insolvency of Inventux in month 26) by redistributing tasks.
In total 6 partners have joined by the Fast Track consortium during the project. Two of filled positions that were left open at the beginning of the project: partner 20 (OMT, position X) in month 8, partner 21 (HyET Solar, position Y) in month 8. Four other partners were found to take over tasks of partners that left the project: partner 22 (Inventux, taking over the tasks of partner 13) in month 9, partner 23 (3SUN, taking over the tasks of partner 12) in month 11, partner 24 (Solayer, taking over the tasks of partner 14) in month 20, partner 25 (Morphotonics, taking over the tasks of partner 20) in month 30.

From the fact that also in times of limited personnel capacity and investment possibilities, the Fast Track consortium was able to attract suitable new replacing partners that were willing to participate and invest, it can be concluded that the work plan and intermediate results of the consortium have always been attractive for the PV community by showing that in this unique collaborative effort of the leading EU industries and research institutions the right way was chosen to go beyond the current technology status
The cooperation in the project has been very constructive and the partners from research and industry have very openly exchanged insight, results, materials, and partially processed devices and modules. This cooperative spirit resulted in fruitful project meetings, punctual delivery of deliverables and reports and the successful abstention of the most important project goals.
As a result of the constructive cooperation in the project, various bi- and multilateral cooperation will be continued after the project. For example 3SUN – HyET Solar, DSM Advanced surfaces – Morphotonics – HyET Solar, HyET Solar – TU Delft.

1.2.2 Objectives
In a unique collaborative effort of the leading EU industries and research institutions in the field, the consortium planned go beyond the current technology status aiming to achieve the following objectives:
- The main objective of the project is to perform a redesign of the multi-junction thin-film silicon (TFSi) devices, incorporating all ideal new features and novel materials, and to bring the processes up to life into the production size pilot lines of the industrial partners.
- It aims to induce a next generation of modules with 12% efficiencies (against 8 to 9.5% in production, and 10% at pilot line level in 2011).
- The stable cell efficiencies are aimed to cross 14% (against 11.9% on glass in 2011).
- An evaluation and a roadmap of the potential to reach efficiencies > 15% will be established.
- New deposition technologies for next-generation low-cost large-area modules will be assessed.
- Production costs will be reduced until below 0,5 € / Wp on module level (against > 1 € / Wp in 2011)
Implications for cost of ownership for installations based on the achieved technology improvements will be derived.
From the further sections it can be concluded that the Fast Track consortium has been successful in their missions and has almost reached all objectives.

Project Results:
The technical results obtained in the project are summarized in detail in section 1.3.2 and further. Here the results are interpreted in view of the project aims and project milestones. In the further sections below, the impact of the project and the exploitation plan are discussed. The consortium has obtained good results on the developments of different components and on the development of integrated lab cells and modules. The
following high-lights can be reported. For the details I refer to the corresponding technical sections.
- A very important result obtained within the Fast Track project is that nanostructured alloyed doped layers (especially p- and n-type μc-SiOx:H as well as p-type a-SiC:H) are favourable for cell performance in both top and bottom cells. This has lead to three world records:
o a-Si WR: Forschungszentrum Jülich has obtained a stabilized record efficiency of 10.26% by applying a standard a-Si:H absorber layer.
o uc-Si WR: For microcrystalline silicon (μc-Si:H), a previous certified world record efficiency of 10.7% has been obtained at EPFL on an area slighltly greater than 1 cm2.
o A record stabilized efficiency of 12.6% was obtained for an a-Si:H/uc-Si:H tandem device.
With that device Fast Track holds the highest reported value for a conversion efficiency of an a-Si/μc-Si tandem solar cell, which makes the project a success.
- The development of antireflection coatings is a great success; an advantage of this technology is its applicability to all photovoltaic technologies, not only thin film silicon.
- Promising new reactor designs to increase up-time and throughput have been demonstrated by depositions on 2 substrates in one plasma zone.
- Various large-are demonstrators of modules and add-ons have been presented at the final project meeting. The performance could be on-line monitored under out-door conditions.
- The consortium has gained a lot of understanding on the production processes of the different production steps. Diagnostic tools dedicated to monitor the crucial production steps have been developed and implemented
- The consortium has developed a number of add-ins and add-ons that can be independently applied and have complementary contributions to efficiency gain.
- Costs level of below 0.5 €/Wp: achieved 0.48 €/Wp. From the CoO calculations we conclude that: 500 MWp production line, in which the major developments of FastTrack are implemented, and producing modules with an efficiency of 12%, can produce modules at a cost level of 0.41 €/Wp. This is a significant improvement with respect to the state of the art production prior to the project (the reference process in this study) for which we calculated a cost level of 0.48 €/Wp for a similar production line without implemented Fast Track technologies.
- From the life cycle analyses, we conclude that the Fast Track technologies have the potential to reduce the energy payback time and carbon footprint on the PV module level by ~ 25-30 % with respect to the state of the art production process prior to the project.
As a result of the very good cooperation between the research and industry partners, the consortium has worked at the front line of the TF-Si technology and has moved this line further forward by presenting worldleading results.

Further detals are reported in the file attached.

Potential Impact:
The project has led to a number of cost-reducing and efficiency improvising concepts that are partially already implemented in production. This has led to a cost reduction due to which the end users are in a competitive position in the PV-marked. The exploitation plans of the partners are summarized in the section below on Exploitation activities. From this, the benefits for commercial and scientific exploitation of the results become clear. A part of the developed technologies can be exploited for different PV technologies (outside TF-Si) and another part even outside the PV Technology.

Market study
In an accompanying market study the requirements for potential applications of the new technologies in the main market segments BIPV and solar parks will be determined by means of key parameters such as system costs, maximum power and voltage, energy yields, design, weight or long term stability of the modules. In this way, the module development in WP5 will be directly driven by market needs to establish a potential Industrial take-up of the project results.
Final report on market analysis for park applications (full report in D7.6)
The PV Market medium term outlook is very promising. In particular, the solar park application will continue to represent an important share of the PV market and together with wind power has the potential to contribute to the global energy supply on a large scale.
In fact, the Solar Park market could quadruple in the next 5 years, if adequate support mechanisms are accompanied by the solution of some known key issues, such as the integration with the existing centralized grid, solar power intermittence and energy storage needs. In the past years the trend toward increasing competitiveness for Solar PV has been driven by Europe and North America, giving way to a more sustainable market with different regions around the world driving different segments. PV Module Market has been served mainly by the crystalline and thin film technologies and this is not going to change in the medium term period.
During the recent years of huge PV market growth in Europe, the crystalline technology dominated the PV modules market and the proportion of thin-film modules in the overall amount of modules produced was low and in steady decline, reaching only 12% in 2012.
This trend can be inverted in the medium term, with thin film technology aiming to a larger market share in particular in the high potential solar park business.
In fact, moving forward, the “sunbelt region”, the area between +35° and -35° latitude, is the biggest growth opportunity for PV solar park application.
Thin film technology has unique features that are ideal for the low latitude and hot climate Sunbelt region, such has a lower temperature coefficient, better performances in diffuse light conditions, a higher energy conversion than the crystalline technology. Therefore thin film technology is very appealing for future PV projects in the Sunbelt Countries, more than it was for PV installations in the northern hemisphere.
Nevertheless, thin film R&D must aim to improve efficiency further in order to lower the gap with the higher efficiency offered by the market leader and more mature crystalline technology. This can be done by either minimizing optical losses (light trapping) or improving solar spectra light absorption (better absorbers) and finally reducing electrical losses.
This is especially vital for micro-morph silicon, which needs to increase its efficiency by two percentage points to be competitive.
Efficiency improvements should have no negative impacts on modules cost. Actually, the other goal is to increase thin film productivity reducing material costs, increasing throughput and improving automation, in order to compensate the remarkable cost reduction that crystalline technology enjoyed in the past few years.
The combination of thin film module performance increase in conjunction with significantly reduced manufacturing costs will ensure the medium-term competitiveness of thin film technology in the very high potential PV market.

Further inforamtion, tables and data on the project related impact are reported in the file attached.

Conclusions from analysis of cost and impact
For all new approaches proposed in WPs 1-6 both the cost of module fabrication for a commercial production plant with an annual production of 500 MW targeting less than 0.5 €/Wp and the reduction of the environmental impact taking into account material and energy usage, energy payback time and equivalent CO2 emissions has been analyzed.
In this study we performed a cost of ownership calculation and a life cycle analysis of a 500 MWp production line of thin film silicon modules on glass, in which all major new concepts as developed in the project FastTrack have been implemented.
From the CoO calculations we conclude that: 500 MWp production line, in which the major developments of FastTrack are implemented, and producing modules with an efficiency of 12%, can produce modules at a cost level of 0.41 €/Wp. This is a significant improvement with respect to the state of the art production prior to the project (the reference process in this study) for which we calculated a cost level of 0.48 €/Wp.
From the LCA we conclude that: the Fast Track technologies have the potential to lower the energy payback time and carbon footprint on the PV module level by ~ 25-30 % with respect to the state of the art production process prior to the project.

The work performed during the FAST TRACK (36 months) resulted in a very active website (both the public and restriced area) and in many different publications and, more in general in different dissemination activities. The complete lists is completed in the Participant Portal and will be included in the project Final report.
Different channels (almost all the possible ones for presenting scientific results) have been used to disseminate outcome of the project. The different channels are:
- Publications in peer reviewed Journals
- Publications for proceedings
- Oral presentation at conferences
- Poster presentations
- Applications for patents
- Thesis and Dissertations (PhD and Master level)
- Organization or participation at Workshops or Exhibitions
The report shows how the project had a relevant impact in the scientific community but also in the education of future scientists that may play a role in the real life application of the project’s results.
The topics covered include:
- Light trapping
- Deposition techniques
- Triple junctions
- Results by using different materials (including doping material)
- Coatings
- Etc.

Further information on all dissemination and exploitation activities performed are reported int he file attached to this report.

List of Websites:

Public website: www.fast-track.eu