US team smashes solar PV efficiency record

Researchers at the US Department of Energy's National Renewable Energy Laboratory (NREL) have become the latest to lay claim to the title of world's most efficient photovoltaic cells, debuting a cell design they claim has achieved 40.8 per cent conversion efficiency.

The battle to claim the world record for solar cell efficiency is highly contentious, with several research teams claiming the unofficial title of most efficient cell already this year. However, with most previous claimants of the title boasting solar cells with efficiencies ranging between 20 and 25 per cent, the NREL team appears to have smashed the previous record.

The 40.8 per cent conversion rate was measured under concentrated light 326 times more intense than that which hits the Earth on a typical sunny day. The NREL said that the cells ability to cope with this intense concentration of light made the design "a natural candidate" for use on space satellites and in emerging solar farms that combine PV panels with the solar concentrating mirrors and lenses widely used by solar thermal technologies.

It added that the cell, which was originally designed by Mark Wanlas and has been improved upon by a team led by John Geisz, uses a composition of gallium indium phosphide and gallium indium arsenide, which sits on top of a germanium wafer and splits the solar spectrum into three equal parts that are absorbed by each of the cell's three junctions, greatly enhancing efficiencies.

The cell is also extremely thin and light, suggesting that it could also deliver advantages in terms of cost and operation if commercialised.