Solar cell converts 40.7% of sun into electricity

Stan Beer
Friday, 08 December 2006 03:19

Science - Climate

A subsidiary of Boeing, has set a new world record in converting sunlight into electricity with a new type of land-based solar cell. The new photovoltaic cells, which are currently being tested in the Australian desert, can convert 40.7% of the sun's energy into electricity, smashing the previous highest performance mark of 33%.

Typically, the best solar cells in commercial production today and used to generate electricity on the roofs of homes, run at a maximum of 14% efficiency. This means that only about one seventh of the sun's energy is converted to electricity, while the rest is lost as heat. However, research has shown that at least 65% efficiency is possible.

Boeing subsidiary Spectrolab demonstrated the ability of its terrestrial concentrator photovoltaic cells to convert 40.7% of the sun’s energy into electricity in a 33-kilowatt full-scale concentrator system in the Australian desert. The company says the results have been verified by the US Department of Energy’s National Renewable Energy Laboratory (NREL).

"This solar cell performance is the highest efficiency level any photovoltaic device has ever achieved," said Dr. David Lillington, president of Spectrolab. "The terrestrial cell we have developed uses the same technology base as our space-based cells. So, once qualified, they can be manufactured in very high volumes with minimal impact to production flow."

According to Spectrolab, high efficiency multijunction cells have a significant advantage over conventional silicon cells in concentrator systems because fewer solar cells are required to achieve the same power output. The technology will dramatically reduce the cost of generating electricity from solar energy as well as the cost of materials used in high-power space satellites and terrestrial applications, Spectrolab said in a statement.

"These results are particularly encouraging since they were achieved using a new class of metamorphic semiconductor materials, allowing much greater freedom in multijunction cell design for optimal conversion of the solar spectrum," said Dr. Richard R. King, principal investigator of the high efficiency solar cell research and development effort. "The excellent performance of these materials hints at still higher efficiency in future solar cells."

While 40.7% efficiency is impressive, research has shown that there is still considerable upside for the improvement of photvoltaic efficiency. In 2005, NREL researchers produced a paper showing that it may be possible to produce solar cells with 65% efficiency using nanocrystals called quantum dots, which produce three electrons for each photon of light that strikes the cell instead of one.

Spectrolab says it has recently signed multi-million dollar contracts for its high efficiency concentrator cells and is anticipating several new contracts in the next few months.