Sharp to Release Polycrystalline Si Solar Cell with 14.4% Conversion Rate
by Motonobu Kawai, Nikkei Microdevices, June 5, 2008
Source: TechOn
http://techon.nikkeibp.co.jp/english/NEWS_EN/20080605/152883/
Sharp Corp will release its “ND-191AV” polycrystalline Si solar cell module, which has a high module conversion efficiency of 14.4%, targeting Japanese houses. The number of bus bar electrodes was increased from two to three, and the widths of all the electrodes were reduced. With the improvement in conversion efficiency, the module can be installed in a wider range of positions on roofs. Compared with the company’s existing products, the capacity of the roof module is 1.5 times larger on average.
Modification of the surface electrode structure contributed to the improvement of conversion efficiency. Solar cell electrodes are composed of wider bus bar electrodes and thinner finger electrodes. The company increased the number of bus bar electrodes from two to three, while at the same time reducing the width of all the electrodes.
When the number of the bus bar electrodes is increased, the current collection loss can be reduced because the electron migration distance from the finger electrodes to the bus bar electrodes becomes shorter. In addition, the light receiving area becomes larger when the electrode width is reduced.
These modifications lead to the improvement of conversion efficiency. The company also adopted a technique to enhance the reflectivity on the back surface. The maximum output per module is 191W. As a result of increasing the wind pressure resistance, the module can be installed in a wider range of positions. When considering the impact of wind, the existing module has to be installed 300-400mm away from the edge of the roof. The wind pressure resistance of the latest product is improved by redesigning the mounting structure, etc so that it can be installed in a position only 200mm away from the roof edge.