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.