Beyond Zero talks to Professor Martin Green of UNSW

Posted on 05 Feb 2010

The University of New South Wales (UNSW) has dominated the development of standard photovoltaics cells since the mid 1980s and Professor Martin Green has been at the head of the UNSW efforts since the late 1970s. From BP buying into the UNSW's photovoltaic technology in the 80s to the UNSW's recent relationship with Suntech, the UNSW has been at the forefront of photovoltaic development and commecialisation globally. Martin Green is Executive Research Director of the ARC Photo-Voltaic (PV) Centre for Excellence at UNSW and Director of CSG Solar.

(PVs, usually made of silicon, operate by directly converting sunlight into electricity using solar cells).

The UNSW is one of the world's larger university-based groups focussing on PVs and is one of the most successful in terms technology improvement and commercialisation.

Milestones

The first big milestone for Professor Green was the development in laboratory tests of a 20% efficient silicon solar cell in 1985. (The efficiency refers to the electrical power produced by a solar cell as a percentage of the sunlight energy it receives.) This is the solar equivalent of the 'four minute mile'. This has since been improved to 25% efficiency, ('three minute mile' equivalent). The theoretical limit is arguably 29%.

Today, the Centre at UNSW is focussed on achieving improvements in low cost commercial sequences and getting that into manufacturing.

First generation silicon wafer cell compared to new generation thin film solar cell.

Conventional silicon cells, known as first generation cells, use the same type of silicon wafer as used in microelectronics. Wafers are 150mm in diameter and a fraction of a millimetre thick. The thickness reduces as the technology improves. Today manufacturers are working with wafers that are 0.2mm (200 microns) thick. The physics enables light to be stored in the silicon film due to its optical index (it is very dense). Silica thus looks much thicker optically than it is physically. This factor of 50 is able to be capitalised on and makes up for the fact that silica is a weak absorber of sunlight compared to other semi-conductors.

Hence, the program to develop and produce new generation thin film solar cells, ie: very thin layers of silica under glass. Large fields of this technology is now deployed in Germany although it has not yet broken through as a mainstream technology.

Originally supported by Pacific Power, the commercialisation of this new generation technology is now being driven by CSG Solar, an Australian company with a factory establised in Germany.

The focus is currently on research to improve the technology as the market is so competitive.

What other companies have grown out of UNSW work?

A factory in Sydney has been operating since 1981 producing solar cells for powering navigational systems. BP bought the company in 1985 and increased its throughput. Some of the UNSW work on efficiency was licensed by BP in the mid-1980s and put into production in India and Spain. BP’s 'satin technology' is under licence to UNSW and for a long time has been the most efficient panel commercially available. This was their first big commercial success.

Cumulatively there has been approx $1 billion worth of sales of technology under licence to UNSW.

They have since branched out with improved versions of their commercially-oriented technology, eg: Pluto cells marketed by Suntech. Dr. Zhengrong Shi of Suntech Power completed his PhD under Professor Green’s supervision in 1992 and worked with UNSW from the mid-1990s to early 2000s. In early 2000 Dr Shi returned to China and established a manufacturing plant. He continues to commercialise UNSW technology as do other ex-students. China is now the largest manufacturer of PVs and Suntech is the largest silicon manufacturer worldwide! UNSW is interacting with many Chinese companies.

The Pluto panel which has come onto the market recently incorporates new generation, low cost, high efficiency technology based on UNSW’s 25% solar cell research results.

Commercial efficiency for direct beam on Pluto panel

Best results are obtained with the multi-crystalline modules; (more than 18% efficiency expected). There is a huge demand for these and if not available now for people’s roofs they will be by March or April 2010. (Pluto technology applies to both mono-crystalline and multi-crystalline modules. It is good on all quality wafers).

The future of PV technology - competing with conventional power

Most people do not realise that PVs compete with the retail price of electricity, not the wholesale price, although there is prospect of the latter. The costs for PVs does not need to be as low as for wind power to be a competitive technology as wind does not compete well on the retail market. The concept of “grid parity”, where the cost of financing solar panels for your rooftop is a better option than buying electricity from your power company, is relevant to peak use of power. Peak use occurs in the late afternoon and consequently west-facing panels can produce the most useful electricity as it is best matched to overall demand.

Where are the best markets for your products?

Germany is the real driver and has the most successful scheme. The price for electricity produced there is guaranteed and this amount reduces each year so that manufacturers have to think about shaving 10% off the price annually to ensure financial returns for people. In other words, there is continuity and the rules are understood. People are able to make long-term business decisions based on the stability of the scheme.

By contrast, in Australia and the USA things are "stop and go". Small business are built up then struggle to survive and collapse due to the constant changes.

There are signs, however, that more sensible attitudes to the promotion of the industry are developing and other countries are likely to help develop the technology which has so much potential to address carbon emissions in the long term.

The UNSW website - www.unsw.edu.au

CSG Solar website - http://www.csgsolar.com/