Electronics Production | September 19, 2008

Printed Photovoltaics in Japan - a somewhat different approach

Photovoltaics (PV) is progressing from the old crystalline and amorphous silicon to thin film technologies that are increasingly printed. There are several types of solar cell involved and they are all needed as the market grows and fragments.
For example, transparent versions based on inorganic compounds are valued on the face of a wristwatch or on a window. Dye Sensitised Solar Cells (DSSC) are already printed reel-to-reel and they are exceptionally efficient in poor light levels and some even work from heat. They combine inorganic and organic compounds. Printed organic photovoltaics on its own is another option. It promises uses involving very low cost and wide area, despite poor efficiency but life needs to be improved. Thin film cadmium selenide/cadmium telluride versions have already beaten silicon on cost of ownership but it is proving difficult to print so that volume production can be achieved at even lower cost, reports IDTechEx.

Japan is different
The approach to the new PV is very different in Japan. Unlike Western car companies, Honda is making photovoltaics partly because it could help to create the car of the future. The Western car companies take a shorter term view and they even struggle to catch up with Japanese hybrid vehicle technology and the batteries required. In the US, the European invention of DSSC is largely ignored but Japan, like Europe, is energetically pursuing this option. It is intensely interested in G24 innovations in the UK which is already ink jet printing these, reel-to-reel and creating uses from the Antarctic to Africa.

All is not plain sailing in Japan, however. Thanks to government subsidies, the Japanese used to have more PV installed than any other country but the subsidies have now largely dried up. In 2007, PV installations plummeted to 165MW from 287MW the year before. It is the more consistent Germans that now have more installed PV than the rest of the world combined. Some in Japan believe that even conventional silicon can achieve grid parity by 2013 and that it therefore does not need much of a fiscal push. Others see strong reasons for supporting the industry, notably development of a variety of types of thin film PV. For example, what goes on a package or toy is unlikely to be the same as a generator of power into the grid and Japan can excel at all of these, reports IDTechEx.

Many technologies are seen as contributors to this grand vision and already the Research Center for Photovoltaics at the National Institute for Advanced Industrial Science has demonstrated 15.9% efficiency for Copper Indium Gallium Diselenide (CIGS) cells on a rigid substrate and is set for 15% efficiency 30 by 30 centimetre panels by year end. Showa Shell is reportedly near to a major rollout of this technology. Honda Soltec already has its reel-to-reel CIGS PV factory on stream. Honda's next-generation solar cell achieves 50% reduction in the amount of energy consumed during the manufacturing process compared to what is required to produce conventional crystal silicon solar cells. This makes the new solar cell more environmentally-friendly by reducing the amount of carbon dioxide generated even from the production stage.

Other options
Matsushita, Micro-tec, NEC, SEL, Sharp and Tokki are among the other companies developing inorganic compound photovoltaics in Japan, as are many local universities and research institutes. Several are working on DSSC which combine inorganic and organic materials. Konica Minolta, Micro-tec, NEC, Nissan Chemical Industries, SEL, Sharp and other companies are working on purely organic PV backed by many of the leading Japanese universities.

Image Source: vtt


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