Development of Solar Cells with World’s highest Energy Conversion efficiency by SANYO
Looks like Sanyo is all alone in this field by breaking its own record in developing the world’s highest energy conversion efficiency of 23% for crystalline silicon type solar cells for a practical size of 100 cm2 or more. The solar cell is of HIT (Heterojunction with Intrinsic Thin layer) type composed of thin crystalline silicon wafer sandwiched by ultra-thin amorphous silicon layer. HIT structure offers a reduction of recombination loss of the electrical element (charged carrier) by surrounding the energy generating layer of single thin crystalline silicon (c-Si) with high quality ultra thin amorphous silicon (a-Si) layers. The recombination loss occurs at the time when negative electron and positive carriers produced within the solar cell combine and disappear, resulting in a loss in electrical current which is produced by the cell causing a reduction in overall solar cell output. One of the challenges in making solar cells is in reducing of optical absorption loss by making sure the sunlight that hits its surface to be guided to the c-Si, the energy generation layer with the smallest possible absorption loss. HIT type solar cells are no exception that is why SANYO has recently developed the know-how in reducing the optical absorption loss both in the a-Si layer and transparent conductive layer resulting in improved the short circuit current (Isc), the maximum current that can be produced by the solar cell from 39.2mA/cm2 to 39.5mA/cm2. Reduction in resistance loss is yet another major issue in solar cell which occurs during the collection of generated electric current through the surface grid electrode. SANYO has achieved this through improving printing technology resulting in improvement of fill factor from 0.791 to 0.80 , which is division of total output by product of maximum current and voltage than can be produced by solar cell.
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[...] a crystalline silicon substrate and an amorphous silicon thin film. The first announcement on such HIT solar cell by Sanyo was back in May of this year achieving a world’s highest conversion efficiency of 23%. [...]