Transcript document
Narrowly edging out the previous record set by Spectrolab late last year, two scientists at the University of Delaware have just created a new device that can convert 42.8% of the light striking it into electricity. The solar cell, built by Christina Honsberg and Allan Barnett, splits light into three components — high, medium and low energy light — and directs it to several different materials which can then extract electrons out of its photons. One of the device's key elements is an optical concentrator — a lens-type component that increases the cell's efficiency by directing more sunlight to it than would happen naturally. It measures in at just below 1 cm thick, a major improvement over the Spectrolab model which featured a concentrating lens about 1 foot thick. Unlike most concentrators that use a two-axis tracking system to follow the sun, this optical concentrator is also stationary — a major feat. The Defense Advanced Research Projects Agency (DARPA) — which has been funding this and similar efforts through its Very High Efficiency Solar Cell (VHESC) program — hopes to eventually incorporate this technology into portable solar cell battery chargers for American troops. It will now fund a newly formed DuPont-University of Delaware VHESC Consortium to shift production from a lab-scale model to a full-on manufacturing prototype model. 2006 Solar Cell Record WASHINGTON, DC – 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. 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.