New World Record Achieved in Solar Cell Technology

energy.gov, Jan 05, 2007

U.S. Department of Energy (DOE) Assistant Secretary for Energy Efficiency and Renewable Energy Alexander Karsner today announced that with DOE funding, a concentrator solar cell produced by Boeing-Spectrolab has recently achieved a world-record conversion efficiency of 40.7 percent, establishing a new milestone in sunlight-to-electricity performance.  This breakthrough may lead to systems with an installation cost of only $3 per watt, producing electricity at a cost of 8-10 cents per kilowatt/hour, making solar electricity a more cost-competitive and integral part of our nation’s energy mix.

“Reaching this milestone heralds a great achievement for the Department of Energy and for solar energy engineering worldwide,” Assistant Secretary Karsner said.  “We are eager to see this accomplishment translate into the marketplace as soon as possible, which has the potential to help reduce our nation’s reliance on imported oil and increase our energy security.”

Attaining a 40 percent efficient concentrating solar cell means having another technology pathway for producing cost-effective solar electricity.  Almost all of today's solar cell modules do not concentrate sunlight but use only what the sun produces naturally, what researchers call “one sun insolation,”  which achieves an efficiency of 12 to 18 percent.  However, by using an optical concentrator, sunlight intensity can be increased, squeezing more electricity out of a single solar cell.

The 40.7 percent cell was developed using a unique structure called a multi-junction solar cell.  This type of cell achieves a higher efficiency by capturing more of the solar spectrum. In a multi-junction cell, individual cells are made of layers, where each layer captures part of the sunlight passing through the cell.  This allows the cell to get more energy from the sun’s light. Read more at energy.gov