Solar energy researchers at an Australian university have converted over 40% of the sunlight hitting a solar system into electricity, said to be the highest efficiency reported to date.

The record efficiency was achieved in outdoor tests in Sydney before being independently confirmed by the National Renewable Energy Laboratory at its outdoor test facility in the U.S.

The work at the University of New South Wales was funded by the Australian Renewable Energy Agency and supported by the Australia-U.S. Institute for Advanced Photovoltaics.

The researched used commercial solar cells in such a way that the efficiency improvements can be readily accessible to the solar industry. 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 could.

The results are based on the use of focused sunlight, and are particularly relevant to photovoltaic power towers being developed in Australia. Power towers are being developed by Australian company RayGen Resources, which provided design and technical support for the high-efficiency prototype. Another partner in the research was Spectrolab, a U.S.-based company that provided some of the cells used in the project.