Sydney, Dec 8 (IANS): Australian solar researchers have converted over 40 percent of the sunlight hitting a solar cell system into electricity, the highest efficiency ever reported.

The record efficiency was achieved in outdoor tests in Sydney, before being independently confirmed by the National Renewable Energy Laboratory (NREL) at their outdoor test facility in the United States.

"This is the highest efficiency ever reported for sunlight conversion into electricity," said professor Martin Green, director of the Advanced Centre for Advanced Photovoltaics (ACAP) at the University of New South Wales (UNSW).

The 40 percent efficiency milestone is the latest in a long line of achievements by UNSW solar researchers spanning four decades.

These include the first photovoltaic system to convert sunlight to electricity with over 20 percent efficiency in 1989, with the new result doubling this performance.

"The new results are based on the use of focused sunlight and are particularly relevant to photovoltaic power towers being developed in Australia," Green added.

A key part of the prototype's design is the use of a custom optical bandpass filter to capture sunlight that is normally wasted by commercial solar cells on towers and convert it to electricity at a higher efficiency than the solar cells themselves ever could.

Such filters reflect particular wavelengths of light while transmitting others.

"We used commercial solar cells but in a new way so these efficiency improvements are readily accessible to the solar industry," said Mark Keevers, the UNSW solar scientist who managed the project.

The work was funded by the Australian Renewable Energy Agency (ARENA) and supported by the Australia-US Institute for Advanced Photovoltaics (AUSIAPV).

The study is outlined in a paper expected to be published soon by the Progress in Photovoltaics journal.