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2001 R&D 100 Award Winner

Triple-Junction Terrestrial Concentrator Solar Cell

Developers: Dr. Jerry Olson, Dr. Sarah Kurtz, Dr. Daniel Friedman, Alan Kibbler, and Charlene Karmer, National Renewable Energy Laboratory; Dr. Richard King, Jim Ermer, Dmitri D. Krut, Hector Cotal, Peter Colter, Hojun Yoon, Nassar Karam, and Gregory S. Glenn, Spectrolab, Inc.

The triple-junction solar cell — or TJ solar cell — generates a lot of energy from just a very little amount of material. How much energy? A 1-cm2 cell can generate as much as 35 W of power and produce as much as 86.3 kWh of electricity during a typical year under a Phoenix, AZ sun. This means that 100 to 150 of these cells could produce enough electricity to power the typical American household. This cell can do this, first, because it uses a triple-junction approach — which means that it uses three cells stacked on top of each other, each cell of which is tuned to efficiently convert a different portion of the solar spectrum to electricity. As a result, the cell converts as much as 34% of sunlight to electricity, which is almost 40% higher than its nearest competitor, and is the first cell to reach or beat the DOE's One-Third-of-a-Sun initiative. Second, the TJ solar cell is designed to be used under high concentrations of sunlight, several times higher than any other cell. At its highest rated concentration (1200 suns), the TJ solar cell produces three times the power of its nearest competitor. Because of these characteristics, this cell can be manufactured for less than $1.00 per watt.