Pairing cutting-edge technology with market reality at UNSW

The team at the University of New South Wales (UNSW) ARC Photovoltaics Centre of Excellence is focused on pairing cutting-edge technology with market reality, and is well equipped to do so; the University holds one of the world’s leading photovoltaics (PV) devices laboratories, which has been in operation for 30 years. The university will this year start construction of its Solar Industrial Research Facility, which will be the only industrial grade silicon solar cell pilot line in the country.

Under the leadership of internationally recognised solar innovators, Scientia Professors Stuart Wenham and Martin Green, the Centre is a leader in low-cost, first-generation silicon wafer solar cell technology. UNSW holds world records for first-generation silicon solar cell performance, including the record for the highest outright efficiency of 25 per cent. The team’s breakthrough buried-contact, semiconductor finger, laser doped selective emitter technologies have been commercialised in deals with some of the world’s largest solar cell manufacturers. Suntech Power, which was founded by UNSW alumnus Dr Zhengrong Shi, will release on the market its new Pluto technology, developed in collaboration with UNSW, this year. Research is continuing on making silicon wafer technology even more efficient through laser doping, semiconductor fingers, inkjet printing and a range of other innovative techniques.

As materials remain the most expensive component of mass-production photovoltaic cells, UNSW has pioneered second- and third-generation technologies which dramatically reduce the amount of silicon required. The Centre’s second-generation, thin-film technology, known as Crystalline Silicon on Glass, has been commercialised through partner CSG Solar and is in global distribution.

The Centre is also developing third-generation, nanostructured tandem silicon cells, a thin-film technology which offers much higher efficiency gains while maintaining low material costs.

A spin off research strand of silicon photonics draws on all three photovoltaic programs and has delivered breakthrough wafer and cell characterisation methods, currently being commercialised by Sydney company BT Imaging.

The leadership of UNSW’s solar researchers has been consistently recognised in major awards, including Professor Green winning the 2007 Solar World Einstein Award, and Professor Wenham being made a Fellow of the global Institute of Electrical and Electronics Engineers and winning the prestigious William Cherry Award in the USA and the NSW Green Globe Award, all in 2009.

UNSW is a founding member of the Australian Solar Institute, and plans to open its $160 million Energy Technologies Building in 2012.

The CSIRO puts a mirror up to climate change

The Commonwealth Scientific and Industrial Research Organisation’s (CSIRO) work in solar research is based at the National Solar Energy Centre (NSEC) in Newcastle, NSW.

CSIRO’s Energy Transformed Flagship is undertaking a broad solar research program to help Australia make the move to cleaner energy sources and, in doing so, tackle the enormous challenge of climate change.

Earlier this year the Federal Government announced in its budget four solar power plants, which combined, aim at feeding up to 1,000 megawatts back into the national electricity grid. This is the equivalent generating capacity of an average Australia coal-fired power station.

While the specific technologies behind the power stations are yet to be determined, the CSIRO expects that it is likely that solar trough technology will play a part at the beginning, given that this technology has been proven at scale overseas and is ready for a demonstration scale project.

The technology works using trough-shaped mirrors to concentrate the sun’s heat into a circulating fluid which can be used for raising steam for turbines, both while the sun is shining and in the evening using stored heat.

More efficient solar technologies will operate at higher temperatures than troughs can produce. CSIRO is developing such solar thermal technology at the NSEC, and has demonstrated the use of the sun’s heat reflected from 200 mirrors onto a tower, producing temperatures needed to make solar gas (natural gas with changed chemical bonds embodying 25 per cent solar energy). This means that solar energy can be stored and transported. At its peak operation, the solar tower array generates enough energy equivalent to power more than 100 homes.

CSIRO’s Energy Transformed Flagship has recently received funding as part of the Australian Solar Institute to set up a new, fully operational solar tower, mirrored field and heat storage technology integrated into a system capable of generating electricity.

CSIRO is also investigating organic PV solar cells and is working collaboratively with national and international groups to overcome the various challenges associated with organic materials.

An energy storage research program is also underway, which includes research on the UltraBattery – a system that can store solar electricity produced by PV cells or wind energy, and use the electricity to smooth short-term fluctuations in output or to shift power production to times of peak demand.

ANU uses integrated research to find practical cost-effective solutions

Integrating both fundamental and applied research, the Australian National University (ANU) is focused on the development of practical cost-effective solutions for solar industry.

The University’s work is currently focused on advanced solar micro-concentrators, flexible lightweight solar cells for defence and security, and plasmon-nano enhancement for crystalline silicon PV. These and other research directions are integrated within the ANU Centre for Sustainable Energy Systems (CSES) and the ARC Centre for Solar Energy Systems.

CSES has been actively engaged in development of linear solar concentrators for a decade. A large 300 metre square Combined Heat and Power Solar (CHAPS) System was installed at a residential college at the ANU campus, and the focus is now on linear micro-concentrators that offer a low profile, light weight and high performance from the roofs of domestic and commercial buildings for the delivery of solar electricity, solar hot water, solar space heating and solar cooling with a combined efficiency of 60–70 per cent.

The development of solar micro concentrators is being conducted by a research consortium including Silicon Valley company Chromasun Inc, Tianjin University in China and Anna University in India. ANU researchers are focusing on the component of the research involving solar cells and solar receivers. The $2.5 million Australian part of the project is funded jointly by the Asia-Pacific Partnership Program and two International Science Linkage grants. Traditionally solar concentrator receivers have been built with expensive, specialist concentrator cells. The ANU team has developed technology for modifying and upgrading commercially available non-concentrator solar cells to operate efficiently at 20 to 30 suns concentration, which will result in major savings in cell costs.

Under a $2.2 million project, funded by the Australian Department of Defence, CSES researchers are developing ultra-lightweight solar power modules which will be integrated with a soldier’s ensemble. The modules are based on ultra-thin elongate crystalline silicon cells developed at ANU.

An important requirement for the solar mobile power source is to reach a battery charging voltage of 4–12 volts. All silicon solar cells have an output of about 0.5 volt, while the current and power of a cell are proportional to its area. Narrow elongated cells connected in series are capable of reaching the required voltage in small modules of only a few square centimetres.

VICOSC – putting research on the rooftop

The Victorian Organic Solar Cell consortium (VICOSC) was formed in July 2008 to develop flexible, large area, cheap, reel-to-reel printable plastic solar cells, within three years. The consortium brings together Victorian based research groups at the University of Melbourne, Monash University and CSIRO Molecular and Health Technologies, and has combined with industrial partners Securency/Innovia (electronics on plastic), BP Solar (large manufacturer), BlueScope Steel (solar cells on steel) and Merck (polymers) to transfer the technology from Research to Rooftop, with implementation expected in 10–20 years. The aim is to realise a prototype thin film organic solar cell having 7 per cent energy conversion efficiency using standard sunlight, and to expand Victoria’s technological strengths in sustainable energy research to reduce greenhouse gas emission in Australia.

The $12 million VICOSC project has Victorian Government support of $6 million. The consortium continues to develop new plastics, organic molecules and materials to enhance the capture and harvesting of sunlight and to improve device performance. The challenge is to design new materials to absorb more light and self organise on the nano-scale, which can be formulated into new inks for printing.

The research is still in the development phase, and VICOSC acknowledges that the materials that are currently being examined will be superseded by better materials developed in the future. Printing trials conducted at Securency have indicated the relative ease with which plastic solar cell test substrates can be printed.

VICOSC – Improving performance, reducing cost

As with conventional inorganic semiconductors, plastics can be designed to either attract an electron (n-type) or give up an electron (p-type). Lay the two polymers on top of each other, and when light is absorbed it speeds up this process generating a voltage and current. The difference from conventional solar cells lies in being able to form an ink with the two materials and then print or spray paint the mixture to form a solar cell. This is expected to significantly reduce the cost of solar energy with low cost polymers and low cost production.