New Record Solar Cell
41.1% Efficient Solar Cell
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE have achieved a record efficiency of 41.1% for the conversion of sunlight into electricity. Using concentrated sunlight focused onto a small 5 mm² multi-junction solar cell made out of GaInP/GaInAs/ Ge (gallium indium phosphide, gallium indium arsenide on a germanium substrate (whew!)).
“We are elated by this breakthrough,” says Frank Dimroth, head of the group at Fraunhofer ISE. “At all times the entire team believed in our concept of the metamorphic triple-junction solar cells and our success today is made possible only through their committed work over the past years.”
Since 1999, Fraunhofer ISE has been developing highly advanced solar cells. The cells are made from their exotic alphabet soup crystals only by applying a trick called metamorphic growth. In contrast to conventional solar cells, the semiconductors in these cells do not have the same lattice constant (distance between the atoms in a crystalline structure). This makes it difficult to grow the semiconductor layers with a high crystal quality. I imagine it is like trying to stack an even layer of ping-pong balls on a layer of tennis balls using atoms instead of balls.
While Mr. Dimroth is justifiably elated by this work, the breakthrough is more in the area of manufacturing, not in solar efficiency. The 41.1% conversion efficiency is just slightly better than the previous world champion cell which has a conversion ratio of 40.7 percent efficiency previously demonstrated by Spectrolab.
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Photo: Fraunhofer ISE
