Developing Solar Cells to Achieve Record-Breaking 40% Conversion Efficiency
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February 2012 Sharp Corporation ・Research and Development of Photovoltaic Power Generation New Energy Technology/Research and Development of Advanced Solar Cell Technology/Development of Manufacturing Technologies for Ultra-high Efficiency Crystalline Compound Solar Cell Modules (FY2001‒FY2003),etc. Developing Solar Cells to Achieve Record-breaking 40% Conversion Efficiency There are high expectations regarding solar cells as a means of renewable energy. To continue the spread of their use, further enhancement of module conversion efficiency is critical. For many years, Sharp Corporation has been committed to conducting research and development on a variety of solar cells, such as compound solar cells, through the Research and Development of Photovoltaic Power Generation Technology project launched by NEDO in 2001. Applying the expertise it acquired through NEDO’s project, Sharp developed triple-junction compound solar cells which today are the primary solar cells Triple-junction compound solar cell achieves a mounted in satellites used around the world. In 2002, record-breaking 36.9% conversion efficiency. Conversion efficiency of a non-concentrated solar cell at the the company’s triple-junction compound solar cell research stage as of November 2011 was certified by the Japan Aerospace Exploration Agency (JAXA), which has led to its widespread use in the aerospace industry. In 2004, cells were installed in a small scientific satellite named "REIMEI" 2009, they Triple junction compound Polycrystalline silicon solar solar cells for space use cells for residential use were adopted for the greenhouse gas observation Energy conversion efficiency satellite "IBUKI". Solar photo-energy distribution As a result of its research and development efforts, Sharp achieved a solar cell conversion efficiency of 35.8% in 2009, a world record. In 2011, the company broke this record by increasing cell conversion Top efficiency to 36.9%. Today, Sharp is continuing its research and development efforts toward achieving a Middle cell conversion efficiency of 40% (non-concentrated) Bottom and 50% (concentrated) by 2025. The company is also working to move its concentrated photovoltaic Compared with polycrystalline silicon solar cell, a power generation system to the practical application triple-junction compound solar cell is able to convert a wide range of sun light to electricity, thus achieving high stage. The concentrated solar module has a target conversion efficiency. conversion efficiency of more than 40%, which will be achieved with concentrated solar power through the use of a specially designed lens and other Sharp Corporation components. 8 March 2009 KANEKA CORPORATION ・Development of Technology to Accelerate the New Energy Dissemination of Photovoltaic Power Generation Systems (FY2000‒FY2005) New Hybrid Solar Cells: Promising Technology for the Solar Cell Market Solar power generation, which uses sunlight̶an infinite source of energy̶has been receiving a great amount of attention as we continue to move toward becoming a low-carbon society. Since 2003, solar cell production has grown rapidly at an annual rate of 30 to 50%. In Japan, government poli- cies to increase installed solar power generation capacity have revived subsidies earmarked for house- holds that have installed solar power generators since 2009. Amidst mounting expectations for the expansion of the New HYBRID™ photovoltaic panel solar cell market, Kaneka Corporation has focused on solar cell development, most recently launching a new HYBRID™ solar module, which incorporates the compa- ny’s unique technologies. Generally, two types of materials are used in the pro- duction of a solar cell; amorphous silicon and thin-film microcrystalline silicon. The former efficiently absorbs short-wavelength ultraviolet rays; the latter absorbs long-wavelength infrared rays. To make use of the merits in which their effective wavelengths and conditions for use differ, Kaneka developed a hybrid tandem-type solar panel, which is composed of dual layers of amorphous Photovoltaic modules incorporated into tiles silicon and thin-film microcrystalline silicon. The most important aspect of solar cell performance is Sunlight conversion efficiency. Kaneka’s new HYBRID™ solar cell boasts a conversion efficiency that exceeds that of Glass normal tandem-type cells by efficiently capturing light Transparent electrode through the use of transparent interlayers. Amorphous silicon Conserving resources, improving production efficiency Transparent interlayers and lowering costs are important factors in the solar cell business. In particular, improving a solar cell’ s conversion Thin-film microcrystalline silicon efficiency maximizes cost reductions. Kaneka has already started producing large modules Back electrode for European countries, including Germany. In Japan, demand is growing for solar cells that can integrate into Cross-section of Kaneka’s New HYBRID™ solar cell and blend well with their surroundings. Thus, Kaneka is Sunlight is captured and sandwiched between transparent focusing its efforts in this area. In 2010, the company interlayers, thus enhancing its conversion efficiency. released a line of solar cells with an energy output KANEKA CORPORATION equivalent to 55 MW and demand is steadily increasing. 9 February, March 2010 SHOWA SHELL SEKIYU K.K. ・New Sunshine Project/Research and Development of New Energy Photovoltaic Power Generation Technology (FY1993‒FY2000),etc. Mass Production of New Non-silicon Solar Cells The development of renewable energy is gaining ufacturing plant, the world’s largest, with an annual momentum as a solution to the depletion of fossil production of 900 MW, which expanded the compa- fuels and global warming. Renewable energy is ny’s overall production scale into gigawatts. Through expected to play a key role in alleviating or resolving Solar Frontier, Showa Shell is utilizing technologies these problems, and solar cells of varying materials developed through NEDO projects to continue to and power-generating mechanisms are being devel- expand its solar cell business, which has become one oped amid fierce competition throughout the world. of its core businesses. There is one solar cell for which specific goals have been set towards resolving issues associated with their development and performance, namely improv- ing energy conversion efficiency, establishing stable manufacturing technologies and reducing costs. Con- tinuous progress is being made to achieve these goals with development and performance enhancements being rapidly applied to an innovative new solar cell that shows great promise̶the CIS thin-film solar cell under development by Show Shell Sekiyu. CIS denotes the components that comprise the solar cell; copper (Cu), indium (In) and selenium (Se). Thin film laminated on glass substrate Showa Shell Sekiyu started developing this solar cell as part of the New Sunshine Project, which was launched in 1993. In subsequent NEDO projects, the company sought to realize the high potential that is Monocrystalline silicon unique to CIS-based solar cells by developing large-ar- Crystalline Polycrystalline silicon ea structurally-integrated solar cells. By consistently silicon Silicon improving the manufacturing process and optimizing Amorphous Microcrystalline Thin-film silicon silicon silicon the technology’s design, the company was successful in Multi-junction tandem (hybrid type) III-V compound achieving goals that were set for each project. Solar cells multi-junction Chemical In 2006, Showa Shell Sekiyu formed a wholly-owned CIS compound subsidiary, called Showa Shell Solar, to operate its Cadmium telluride (CdTe) CIS-based thin-film solar cell business. In 2007, the Organic subsidiary started manufacturing and distributing the Main types of solar cells CIS-based cells and sales continue to increase globally SHOWA SHELL SEKIYU K.K. (In April 2010 the subsidiary was renamed Solar Fron- tier). In 2011, Showa Shell built its third solar cell man- 10 March 2010 Mitsubishi Heavy Industries, Ltd. ・Development of Advanced Manufacturing Technology for New Energy Photovoltaic Power Generation Systems (FY2000‒FY2001),etc. Development of Large-area High-speed Film Deposition Technology for Sharply Enhancing Solar Cell Productivity Until now, the race to develop solar cells has focused mainly on energy conversion efficiency. How- ever, numerous other factors determine solar cell pro- duction costs. The main challenges the industry is seeking to address are reducing large-area solar cells production times and achieving continuous produc- tion. Mitsubishi Heavy Industries (MHI) has taken on these challenges from the viewpoint of monozukuri (manufacturing), Japan’ s competitive advantage in technology, focusing its endeavors on the develop- ment and production of silicon based thin-film solar Plasma CVD system for manufacturing amorphous silicon solar cells cells that use small amounts of silicon, a material used The star-shape enables short, tandemly-arranged lines and minimizes the impact from any process in the line that has stopped. in most solar cells. Through collaborative NEDO proj- ects between industry and universities, MHI developed a technique for manufacturing solar cells with large surface areas (1.4 m x 1.1 m) as well as a technology to enhance film deposition speed. The result of this collaboration is a film deposition speed that is about five times faster, with an actual production yield of 97%. The solar cells manufactured by MHI are being exported to countries such as Germany and Spain, which have been quick to adopt