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Solar breakthrough could lead to cheaper power

2nd May 2007, 7:15 WST

Cheaper solar power could be available in a few years due to pioneering work by Australian scientists on an improved solar cell.

Researchers at the University of New South Wales ARC Photovoltaics Centre of Excellence have developed a means of increasing the cell's light-trapping ability by up to 50 per cent.

They say that apart from a home's cooking and hot-water heating needs, such improvement to an electric solar system could power an average house with panels covering 10 square metres.

"Overall, our new solar cells increase power generated by 30 per cent," said Dr Kylie Catchpole, co-author of the study.

As part of the process, UNSW researchers, led by Phd student Supriya Pillai, place a thin film (about 10 nanometres thick) of silver onto a solar cell and heat it to 200 degrees Celsius.

The film breaks into tiny 100-nanometre "islands" of silver and raises its light-trapping efficiency.

With this the team can move from thick expensive silicon "wafers" to cheaper "thin film" cells with less silicon.

"Most thin-film solar cells are between eight and 10 per cent efficient, but the new technique could increase efficiency to between 13 and 15 per cent," Dr Catchpole said.

"If they're below 10 per cent efficient, then you can't really afford to install them, because it would take up too much of your roof area, for example, to power your house."

It can start to become commercially viable once the converting efficiency exceeds 10 per cent.

Silicon is a poor absorber of light. That affects the cost of solar technology, as up to 45 per cent of its cost is due to the cost of silicon.

Prices for an installed solar system for an average house could fall 25 per cent from $20,000 to $15,000 once the technology filters through, the researchers say.

There are only 30,000 Australian households out of eight million that have solar panels for electricity.

If this solar system is used with a solar heating system for water and cooking, the excess power generated can be sent back to the power grid.

"You connect with the electricity grid system where you have no batteries and then sell back your excess electricity," Dr Catchpole said.

"You are then not wasting any electricity, similar to Michael Mobb's house (in Chippendale, Sydney)," she said.

The report of the breakthrough will appear in the upcoming issue of the Journal of Applied Physics.