Sets New Record with Concentrator Triple-Junction Compound Solar Cell.
Sharp Corporation has achieved the world’s highest solar cell conversion efficiency*2 of 44.4%, using a concentrator triple-junction compound solar cell. These solar cells are used in a lens-based concentrator system that focuses sunlight on the cells to generate electricity.
This latest Sharp breakthrough came about through research and development efforts that are part of the “R&D on Innovative Solar Cells” project promoted by Japan’s New Energy and Industrial Technology Development Organization (NEDO).*3 Measurement of the value—which sets a record for the world’s highest concentrating conversion efficiency—was confirmed at the Fraunhofer Institute for Solar Energy Systems (ISE)*4 in Germany.
Compound solar cells typically offer high conversion efficiency while utilizing photo-absorption layers made from compounds of multiple elements, such as indium and gallium. Sharp’s concentrator triple-junction compound solar cells use a proprietary technology that enables the efficient conversion of sunlight into electricity by means of a stack of three photo-absorption layers, the bottommost of which is made from InGaAs (indium gallium arsenide).
To achieve a concentrating conversion efficiency of 44.4%, Sharp worked to widen the effective concentrator cell surface and ensure uniformity of width at the interface of the connecting concentrator cell and electrodes.
Because of their high conversion efficiency, compound solar cells have thus far been used primarily on space satellites. Looking to the future, Sharp aims to harness this latest development success and make the use of compound solar cells more feasible in terrestrial applications.
- *1 Conversion efficiency confirmed by the Fraunhofer Institute for Solar Energy (ISE, one of several organizations around the world that officially certifies energy conversion efficiency measurements in solar cells) in April 2013 under a light-concentrating magnification of 302 times (cell surface: approx. 0.165 cm2).
- *2 As of June 14, 2013, for concentrator solar cells at the research level (based on a survey by Sharp).
- *3 NEDO is one of Japan’s largest public management organizations for promoting research and development as well as for disseminating industrial, energy, and environmental technologies.
- *4 ISE was one of the participating members from the EU side at “NGCPV: A new generation of concentrator photovoltaic cells, modules and systems.” The collaboration is part of the R&D in Innovative Solar Cells project.
- *5 InGaP: Indium Gallium Phosphide
GaAs: Gallium Arsenide
InGaAs: Indium Gallium Arsenide
Tunnel junction: Semiconductor junction where electricity flows as if through metal
Buffer layer: A layer sandwiched between two materials to accommodate differences in their structures.
History of Sharp Compound Solar Cell Development
|1967||Development begins of solar cells for space applications using single-crystal silicon.|
|1976||Launch of operational Japanese satellite, “Ume,” equipped with Sharp solar cells for space applications (single-crystal silicon solar cell).|
|2000||Research and development begin on triple-junction compound solar cells to further improve efficiency, reduce weight, and increase durability of solar cells for space applications.|
|2001||Participation in research and development on NEDO’s photovoltaic power generation themes.|
|2002||Triple-junction compound solar cell gains certification from the Japan Aerospace Exploration Agency (JAXA).|
|2003||Conversion efficiency of 31.5% is achieved (at the research level) for a triple-junction compound solar cell.|
|2005||Launch of small scientific satellite, “Reimei,” equipped with Sharp triple-junction compound solar cells.|
|2007||Conversion efficiency of 40.0% achieved (at the research level) for a triple-junction compound solar cell (concentrator type, at 1,100 times concentrated sunlight).|
|2009||Launch of Greenhouse Gases Observing Satellite (GOSAT), “Ibuki”, equipped with Sharp triple-junction compound solar cells.|
|2009||Conversion efficiency of 35.8% is achieved (at the research level) for a triple-junction compound solar cell.*6|
|2011||Conversion efficiency of 36.9% is achieved (at the research level) for a triple-junction compound solar cell.*6|
|2012||Conversion efficiency of 43.5% achieved (at the research level) for a concentrator triple-junction compound solar cell (concentrator type, at 306 times concentrated sunlight)*6|
|2013||Conversion efficiency of 37.9% is achieved (at the research level) for a triple-junction compound solar cell*6
Conversion efficiency of 44.4% achieved (at the research level) for a concentrator triple-junction compound solar cell (concentrator type, at 302 times concentrated sunlight)*6
- *6 Based on research and development efforts that are part of NEDO’s R&D on Innovative Solar Cells project.