Wednesday, May 02, 2007

solar - the larger picture

concentrator photovoltaic technology in Central Australia

The most recent issue of Cosmos carries an article on solar technologies, a subject of some interest for La Luna Housing Co-op, a co-op that is looking into enviro-friendly technologies, small and large, for our properties.

Sales of solar panels have soared in recent years, what with global warming concerns and oil price rises and the rising cost of electricity. The increase in sales is also most definitely tied to subsidies. Government interest has meant a greater mainstreaming of the technology. As Cosmos points out, the grid-connected market today accounts for some 83% of solar sales. The Japanese and German governments have led the way in this area, but many other countries, and powerful not-quite-countries such as California, are hurrying to catch up. These subsidies, together with increasing taxation of emissions from the traditional fossil fuel industry, not to mention increasing extraction and other costs, have made solar technology much more competitive, and double-digit growth is predicted for the foreseeable future.

Unfortunately, though, the real cost of manufacturing solar panels has increased significantly in recent times, largely because of a shortage of silicon. The shortage has meant that the price of the raw material has risen by almost a factor of 6. Boosting production of the purified silicon involves a great deal of expense.

So, can photovoltaic cells be manufactured without silicon, or with much less silicon? This is where Australian research is coming to the fore. The sliver cell panel, which uses micro-machined slivers of silicon instead of the traditional silicon wafers, was developed at the Centre for Sustainable Energy at the ANU. A square metre of such slivers will do the job of a 15cm wafer. Another Australian innovation is CSG – crystalline silicon on glass. This is an enhancement of wafer technology which requires 99% less silicon. The technology has been driven offshore due to lack of reliable funding and support. Australia’s government occasionally tries to get in on the act with rhetoric about solar cities, but there’s been little substantial funding for Australia’s solar pioneers, when compared with the funding of solar technology in Europe, particularly in Germany. This has meant that graduates in photovoltaic systems as well as the technologies they develop are being forced out of the country.

Along with photovoltaic panel technology there is a technology called concentrator technology which has been gaining lots of attention lately. The name provides the idea: rather than broad panels which trap as much of the sun’s generous spread of energy as possible, concentrator approaches direct the resource in much the same way as a lens, to create a powerful beam. In fact the latest developments have employed both beams and panels to provide power to remote Aboriginal communities, with curved-mirror tracking dishes concentrating light by 500 times and reflecting it onto specially insulated solar panels, and more ambitious systems are currently being built in regional Victoria. Meanwhile efforts are under way in California to reduce the cost of silicon manufacture substantially. Solar technology is getting hotter all the time at the moment.



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