Electric has claimed a new record conversion efficiency rate of 18.6
percent for multi-crystalline silicon solar cells – an improvement of
0.6 percent over the company’s previous record announced in May 2007.
The achievement was reported to be due to the addition of a low reflectivity surface texture, which is a hexagonal structure with bowl-shaped concaves approximately 10 micrometers in diameter, created by combining specific laser patterning and wet etching processes.
Previously, Mitsubishi has said that an RF plasma Reactive Ion Etching (RIE) process rather than a wet etch process had been used to decrease reflectivity.
The use of thinner wafers (no thickness specification given) also contributed to the efficiency improvement, according to Mitsubishi.
With modified screens and front metal electrodes, Mitsubishi Electric also reduced shading loss of front grid electrodes by 25 percent compared to previous cells.
Mitsubishi Electric said it would introduce the new technology into its mass-production in fiscal 2011 (April 1, 2010 – March 31, 2011). Mitsubishi’s previously announced 18 percent efficiency cells are being introduced into production from the beginning of 2008.