Solar researchers working at the University of New South Wales (UNSW) claim to have produced a system that converts over 40 percent of incoming sunlight into electricity, thereby taking the title of highest solar efficiency for a photovoltaic system ever reported.

The researchers first achieved their record efficiency in indoor tests in a facility in Sydney, Australia, and then had these achievements duplicated and ratified by the National Renewable Energy Laboratory (NREL) using an outdoor test facility in the United States.

"This is the highest efficiency ever reported for sunlight conversion into electricity," said UNSW Professor Professor Martin Green, Director of the Australian Centre for Advanced Photovoltaics (ACAP).

The record was achieved using a combination of technologies, including heliostat mirror "power tower" concentrators from Australian company RayGen Resources and high-efficiency photovoltaic (PV) cells from Boeing subsidiary, Spectrolab, but the key component to achieving such a high-efficiency was in the use of a specifically-designed optical bandpass filter used to reject certain components of the light spectrum whilst improving the capture of others. This helped to vastly improve the conversion of light to electricity at a higher efficiency than possible using PVs alone.

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

"We used commercial solar cells, but in a new way, so these efficiency improvements are readily accessible to the solar industry," added Dr Mark Keevers, the UNSW solar scientist and manager of the project.

Whilst other focused sunlight solar energy systems like the CSIRO’s supercritical-steam set-up or the recent Ethiopian installation of the Tulip system have been shown to produce large amounts of energy, both use either water or hot air to drive turbines to produce electricity. The UNSW system, by comparison, is potentially a lot less complex, cheaper, and safer than such systems and, as a result, may be more readily incorporated in domestic and commercial situations.

The UNSW solar researchers have produced a large number of achievements in the field of solar energy in the past four decades, including the first photovoltaic system to achieve a conversion rate of sunlight to electricity of over 20 percent efficiency way back in 1989.

The UNSW solar energy research has been funded by the Australian Renewable Energy Agency (ARENA), whose CEO, Ivor Frischknecht, praised the recent achievement as another world first for Australian solar research and development and believes that it aptly demonstrates the value of investing in Australia’s renewable energy creativity.

"We hope to see this home grown innovation take the next steps from prototyping to pilot scale demonstrations," says Mr. Frischknecht. "Ultimately, more efficient commercial solar plants will make renewable energy cheaper, increasing its competitiveness."

The work was also supported by the Australia–US Institute for Advanced Photovoltaics (AUSIAPV).

The results of this research will be presented at the Australian PV Institute’s Asia-Pacific Solar Research Conference, and a paper by the researchers is to be published soon in the journal Photovoltaics.

Source: UNSW