Mitsubishi Develops World’s Most Efficient Multicrystalline Si Solar Cell
Motonobu Kawai, Nikkei Microdevices / Mar 21, 2008
Source: TechOn
http://techon.nikkeibp.co.jp/english/NEWS_EN/20080321/149296/
Mitsubishi Electric Corp scored a world record conversion efficiency rate of 18.6% in a multicrystalline Si solar cell. The cell uses the company’s new technology called “honeycomb texture,” which was unveiled in February 2008. The efficiency rate was measured at the National Institute of Advanced Industrial Science and Technology, a public standards agency in Japan.
Thus far, the highest conversion efficiency rate of a multicrystalline Si solar cell was 18.5%. This was achieved by the cell with a new electrode structure called “back contact,” which was developed by Kyocera Corp. Mitsubishi’s latest development indicates that a cell with a standard electrode structure can provide higher conversion efficiency than that of the back contact cell.
Mitsubishi aims to increase its annual output to 500MW in fiscal 2012. Mass-production of cells based on the honeycomb texture technology, which was a key to make the world record, is scheduled to start in fiscal 2010 or later. When the cell conversion efficiency improves from 16 to 18%, the output is increased by 0.4W per 150mm square cell. With the use of a module composed of an array of 50 cells, the module conversion efficiency will increase by 20W.
To form a honeycomb textured structure, 100 million holes must be made by laser beams on a SiN film formed on the surface of a 150mm square cell. One of the issues for mass-production is to improve the throughput of laser processing equipment, which will be developed in-house. The improvement in throughput will lead to a reduction in the production cost per output.