Sharp solar cell achieves top efficiency of 44.4%

26 Jun 2013

New record set by concentrator triple-Junction compound device.

Sharp has achieved the world's highest solar cell conversion efficiency 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.

The 44.4% conversion efficiency was 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).

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), one of Japan's largest public management organizations for promoting research and development as well as for disseminating industrial, energy, and environmental technologies.

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) in Germany; 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.

Indium gallium arsenide

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 bottom-most 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.

Look Sharp – Firm’s history of compound solar cell R&D

1967 - Development begins based on single-crystal silicon.

1976 - Launch of operational Japanese satellite "Ume", equipped with Sharp single-crystal silicon solar cell.

2000 – R&D begins on triple-junction compound solar cells to improve efficiency for space applications.

2001 - Participation in R&D on NEDO's photovoltaic power generation projects.

2002 - Triple-junction compound solar cell (TJCSC) gains certification from the Japan Aerospace Exploration Agency.

2003 - Conversion efficiency of 31.5% with TJCSC.

2005 - Launch of satellite "Reimei" equipped with Sharp TJCSCs.

2007 - Conversion efficiency of 40.0% withTJCSC (1,100x concentrated sunlight).

2009 - Launch of Greenhouse Gases Observing Satellite (GOSAT) "Ibuki" with Sharp TJCSCs.

2009 - Conversion efficiency of 35.8% with TJCSC.

2011 - Conversion efficiency of 36.9% with TJCSC.

2012 - Conversion efficiency of 43.5% with concentrator TJCSC (306x concentrated sunlight).

2013 - Conversion efficiency of 37.9% with TJCSC.

2013 - Conversion efficiency of 44.4% with concentrator TJCSC (302x concentrated sunlight).

About the Author

Matthew Peach is a contributing editor to optics.org.