[graffis-l] SOLAR CELL EFFICIENCY RECORD

[Guest guest]

At 08:06 AM 8/8/07, you wrote:

>42.8% Efficiency: A New Record for Solar Cells

>Posted by: " Mark Graffis " mgraffis mgraffis

>Tue Aug 7, 2007 8:37 am (PST)

>

>http://www.treehugger.com2007/08/428_efficiency.php

>42.8% Efficiency: A New Record for Solar Cells

>by Jeremy Elton Jacquot, Los Angeles on 08. 1.07

>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 (a boost that contributed in great

>measure to its record-setting performance). 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.

>

>UPDATE: A reader wanted us to clarify an important point — namely the fact

>that the concentrator itself doesn't increase the efficiency (it actually

>increases the power output by intensifying the beam of sunlight), the

>spectrum splitting optics and solar cells accomplish that.

 

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