Australian educational and research opportunities ...

Solar Energy Materials & Solar Cells 67 (2001) 647}654

Australian educational and research opportunities arising through rapid growth in the photovoltaic industry S.R. Wenham*, C.B. Honsberg, J.E. Cotter, R. Largent, A.G. Aberle, M.A. Green Key Centre for Photovoltaic Engineering, University of New South Wales, Sydney 2052, Australia

Abstract In recent years, the photovoltaic (PV) industry has been growing rapidly at the rate of 30}40% per annum. As a result of this rapid growth, new opportunities through collaborative research with industry and in the educational area have arisen. To address these needs, the Australian government, through the Australian Research Council (ARC), has established a Key Centre for Teaching and Research in Photovoltaic Engineering at the University of New South Wales (UNSW). This is one of only eight such centres established Australia-wide across all disciplines. The primary new initiative of this Key Centre is to establish the world's "rst undergraduate engineering degree in photovoltaics and solar energy, commencing in March 2000. 2001 Elsevier Science B.V. All rights reserved. Keywords: Photovoltaic technology; Silicon solar cells; Photovoltaic education; Engineering

1. Introduction The photovoltaic industry continues to rapidly expand [1] at rates comparable to the telecommunications and computing industries, as seen from Fig. 1. The massive recent growth in residential photovoltaics is expected to continue as ambitious international programs, often o!ering quite generous Government subsidies, collectively target, the installation of more than 3 million photovoltaically active rooftops in residential areas over the coming decade.

* Corresponding author. Tel.: #61-2-9385-5171. E-mail address: [email protected] (S.R. Wenham). 0927-0248/01/$ - see front matter 2001 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 7 - 0 2 4 8 ( 0 0 ) 0 0 3 3 7 - 8

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S.R. Wenham et al. / Solar Energy Materials & Solar Cells 67 (2001) 647}654

Fig. 1. PV market growth using strategies unlimited data.

The massive growth in the industry is leading to many manufacturers installing new manufacturing capacity. In the past, UNSW researchers have developed new technologies such as the buried contact solar cell [2] and subsequently licensed them to industry. However, with the present rapid expansion, opportunities have arisen for UNSW researchers to engage in collaborative research programs with individual companies to either adapt existing technology to suit their needs, provide expertise to assist in the optimisation of their production, or else engage in programs aimed at developing new processes and techniques for new production capacity. Examples of the latter collaborative programs are given in the next section.

2. Collaborative research programs with industry 2.1. Simplixed buried contact solar cell Despite the commercial success of the buried contact solar cell; a signi"cant deterrent to the technology's uptake has been the necessity for industry to invest in entirely di!erent infrastructure and equipment for its manufacture compared to existing screen printed cell technology. A collaborative research program has been established with Eurosolare in Italy with the aim of adapting the buried contact solar cell for fabrication using existing screen printing equipment and infrastructure. A key feature of the new technology is the use of Eurosolare's standard antire#ection coating, which when applied to the grooved surface, provides substantially thicker coating to the light-receiving areas while substantially thinner or even non-existent layer within the grooves. This selectivity facilitates subsequent plating of the metal contacts into the groove regions while simultaneously keeping the light receiving surface metal free through the masking properties of the antire#ection coating. Throughout the remainder of the fabrication sequence, many of the standard processes developed for the screen printing technology are able to be used while most of the high-e$ciency attributes of the buried contact solar cell have been retained.


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2.2. New rear contact design for commercial cells Virtually, all commercially produced silicon solar cells su!er from high rear surface recombination velocities. This does not, in general, seriously degrade device performance as in general the substrate thicknesses are greater than the minority carrier di!usion lengths. Future generations of commercial technology, however, need to be able to utilize substantially thinner substrates to improve the economics and also potentially give performance enhancement. At present, the use of thinner substrates with any existing commercial cell technology will simply lead to performance degradation. A collaborative research program has been established with BP Solar to develop a new rear contacting scheme that simultaneously achieves a much lower rear surface recombination velocity. Solid-phase epitaxial growth of silicon [3] using aluminum for the growth medium is being used to make low-area contact through a rear passivating oxide layer. Using substrates of only about 250 lm thickness, comparable to the corresponding minority carrier di!usion lengths, an increase of approximately 40 mV in open-circuit voltage has been achieved relative to more conventional contacting schemes typical of those used commercially [2]. 2.3. Thin xlm polycrystalline silicon solar cells Paci"c Solar Pty. Ltd. was established as a joint venture between Paci"c Power and UNSW for the purpose of commercializing the new generation of thin-"lm technology developed at UNSW [4]. Due to commercial sensitivities, the commercial implementation of the technology takes place exclusively at the premises of Paci"c Solar with no involvement from UNSW. A collaborative research program, however, has been established whereby the expertise and facilities of UNSW are able to be used to assist in characterizing and analyzing materials and device structures to complement the commercialization program at Paci"c Solar. In a recent press release, Paci"c Solar announced the successful implementation of pilot production of the new technology six months ahead of schedule. The pilot production modules are approximately 30 cm;40 cm. The company anticipates scaling up the technology to full-scale production in the near future. 2.4. Laser doping and self-aligned metallization Multicrystalline silicon substrates in general cannot withstand the same hightemperature exposure as single-crystal silicon substrates. Prolonged high-temperature exposure causes excessive degradation in minority carrier lifetimes. This constraint in general makes it di$cult to produce heavily di!used regions beneath metal contacts. In this collaborative research program with Solarex, laser doping from a spin-on di!usion source is used to provide heavily doped regions at the semiconductor surface where the metal contacts are to be located. The self-aligned feature for the metallization is achieved by using the same dielectric dopant source as a metal plating mask to only allow the metal contact to be formed in the regions where the integrity of the

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dopant source has been destroyed through the laser doping process. Producing the metal contact scheme in this way alleviates the need for high-temperature exposure of the multicrystalline substrates. Nevertheless, the new technology appears capable of still achieving very "ne lines (20}30 lm) and many of the corresponding highperformance attributes normally associated with the buried contact solar cell. Furthermore, the heavy doping beneath the metal provides excellent ohmic contact as well as minimizing the contribution to the dark saturation current from the metal/silicon interface. 2.5. Inverter design The new Paci"c Solar product is expected to be a photovoltaic module with integral inverter for grid connection. A major research program has been established by Paci"c Solar to develop appropriate low-cost, high-e$ciency, high-reliability inverters. The collaborative program established with UNSW makes available the vast experience, facilities and equipment of UNSW and its researchers to assist with the development of this new inverter.

3. New educational opportunities 3.1. Introduction In New South Wales (NSW), Australia, the `Green Powera scheme provides electricity consumers with the option to pay a premium for their electricity but have it generated from `greena environmentally friendly sources such as photovoltaics or wind power. For example, energyAustralia allows consumers to pay a premium in the range of 0}40% for their electricity with a corresponding guarantee that 0}100% of that consumer's electricity will be e!ectively generated from environmentally friendly sources. In recent years, approximately 15,000 new subscribers per year have elected to join this scheme. This type of public support is also apparently experienced elsewhere throughout the world, providing signi"cant opportunities for the PV industry to grow through applications which would not normally be considered economically viable. A recent press release [5] from the New South Wales Minister for Energy, Mr. Yeadon, emphasized the massive growth rate in the `Green Energya sector and associated industries in NSW, claiming it to be outstripping the growth rate of the `Information Technologya sector by 9% per annum. The estimated economic impact of the sector is currently AUD$4.9 billion annually but is expected to grow to AUD$5.5 billion by the end of 2000. During the same period, the study on which the press-release was based forecasts the creation of 1200 jobs directly in the industry. This compares to the 1000 jobs already created in the sector in NSW since 1996. International studies indicate that job creation in the PV sector over the coming decade could exceed 100,000 worldwide [6}8]. With the growing needs of the photovoltaic industry, new opportunities are arising in the educational area and also


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Fig. 2. Job creation by the year 2004 as a function of the annual growth rate of the PV industry from 1998 to 2004 [8].

for collaborative research with industry. To address these needs, the Australian government, through the ARC has established the Key Centre for Photovoltaic Engineering at UNSW with roughly equal emphasis on both teaching and research. This is one of only eight such centres to be established Australia-wide across all disciplines. The primary new initiative of this Key Centre is to establish the world's "rst undergraduate engineering degree in photovoltaics and solar energy. This new degree will commence in March 2000 with approximately 50 new students per year. The "rst graduates will join the workforce in 2004, by which time, international studies indicate that job creation in the PV sector world-wide will likely be in the vicinity of tens of thousands as shown in Fig. 2 [8]. 3.2. New undergraduate engineering degree `photovoltaics and solar energya The new degree in photovoltaics and solar energy will endeavour to train engineers for the entire PV sector, including: research, development, education and training; PV technology, manufacturing, quality control and product reliability; PV applications, system design, performance optimization, system integration, balance of system components (including interface and control electronics), grid interface issues, system analysis, fault diagnosis and reliability, device theory and design; marketing, analysis, life cycle costing, modeling and policy; and a broad education in solar energy, renewable energy technologies and sustainable energy. The funding to support the development of this new program from the ARC extends for a period of six years with the aim of enabling the Key Centre to then become self-sustaining. Substantial levels of funding for the new degree program are also being provided by UNSW (particularly through the Faculty of Engineering), the Sustainable Energy Development Authority in NSW, and the Australian Co-operative Research Centre for Renewable Energy. Strong support is also being provided by manufacturers and end-users.

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The anticipated total cost associated with developing the new undergraduate degree is in the vicinity of US$3 million. Considerable emphasis is being placed on the development and use of innovative teaching aids and materials such as interactive multi-media CD's and web-based teaching. One of our more general photovoltaic engineering subjects `Applied Photovoltaicsa is already being o!ered via the internet with enrolments from a large number of countries. On the two occasions that this course has been o!ered via the internet, demand has greatly exceeded available enrolment places. This internet course is o!ered in conjunction with one of the multi-media interactive CD's [9] developed for this degree program. Promotion of the new undergraduate engineering degree program began in mid1999 via glossy brochures as depicted in Fig. 3 and a promotional CD that is being distributed to all high schools throughout Australia. Within weeks of commencing this promotion, signi"cant interest has been shown by high school students indicating that entry into this new program is likely to require a high tertiary entrance score.

Fig. 3. Glossy brochure promoting new undergraduate engineering degree in photovoltaics and solar energy.


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3.3. Option to specialize in complementary area In recognition of the diversity of engineering skills necessary throughout the photovoltaic sector, this new degree program o!ers students the opportunity to simultaneously specialize in a second area complementary to photovoltaic engineering. These optional strands include electronics, computing, mechanical or environmental engineering, chemistry, physics, mathematics, civil engineering, telecommunications and electrical engineering. Another feature of this new program is that double degree options are being developed whereby the student's elected strand can be expanded into a full second degree through only one extra year of study. This feature appears to be attracting a high level of interest and support from prospective students. 3.4. Collaboration with other institutions Since commencing promotion for the degree in Photovoltaics and Solar Energy, UNSW has received interest from several universities internationally interested in collaboration. The "rst of these collaborations has now been established with Murdoch University, Perth, Australia, where a related new renewable energy engineering degree program will be established and o!ered for the "rst time in 2001. This latter degree program will o!er many of the same subjects possibly taught via the internet, or by students attending the UNSW campus for part of their studies. It is envisaged that over the next couple of years many more of these newly developed subjects will be made available for distance learning via the internet and multi-media interactive CDs. This will enhance the opportunities for collaboration with institutions internationally.

4. Conclusions The evolving needs of the rapidly growing photovoltaic industry have opened new collaborative research and educational opportunities. The Australian government has established a Key Centre for Photovoltaic Engineering, embarking upon collaborative research with industry and the implementation of the world's "rst undergraduate engineering degree in photovoltaics and solar energy. The new degree is being o!ered at the University of New South Wales commencing in the year 2000. As a four-year degree program, the "rst graduates will enter the workforce in 2004 with about 50 graduates per year anticipated in subsequent years. Numerous collaborative research programs have been established with photovoltaic manufacturers to either develop and implement new processes or adapt existing fabrication approaches.

Acknowledgements The Key Centre for Photovoltaic Engineering was established and is funded by the Australian Research Council in conjunction with the University of New South Wales. Other major support for the new educational initiatives is being provided by the

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Sustainable Energy Development Authority in NSW; The Australian CRC for Renewable Energy, Paci"c Solar Pty. Ltd., BP Solar and numerous other organizations; Companies and end-users of photovoltaic product. The contributions of many sta! of the University of New South Wales are also acknowledged, particularly the e!orts of the support sta! of the Key Centre for Photovoltaic Engineering and the Photovoltaics Special Research Centre.

References [1] R. Curry, PV Insider's Report, Vol. XVII, No. 2, February 98, p. 1. [2] S.R. Wenham, Progr. Photovoltaics 1 (1) (1993) 3. [3] L.M. Koschier, S.R. Wenham, M. Gross, T. Puzzer, A.B. Sproul, Low temperature junction and back surface "eld formation for photovoltaic devices, Second World Conference on Photovoltaic Solar Energy Conversion, Vienna, July, 1998, pp. 1539}1542. [4] S.R. Wenham, M.A. Green, S. Edmiston, P. Campbell, L. Koschier, C.B. Honsberg, A.B. Sproul, D. Thorp, Z. Shi, G. Heiser, Solar Energy Mater. Solar Cells 41/42 (1996) 3. [5] K. Yeadon (NSW Minister for Energy), NSW green energy growth outstrips IT and Tourism, Media Release, NSW Government, 16th July 1999. [6] European Commission, White Paper for a Community Strategy and Action Plan, COM(97)599 "nal (26/11/97). [7] M. Bartensterin, Opening Address at 2nd World Conference on Photovoltaic Solar Energy, Vienna, July 1998. [8] S.R. Wenham, C.B. Honsberg, M.A. Green, ANZSES Solar '98 Conference, Christchurch, November 1998. p. 532. [9] C. Honsberg, S. Bowden, Photovoltaics: devices, systems & applications, CDROM, University of NSW, July 1999.