Panasonic have announced that it has achieved a record conversion efficiency of 24.7% at the research level, using HIT solar cells with a thickness of 98 microns. This is the world’s highest efficiency rate for any crystalline silicon-based solar cell of practical size.
The record high efficiency was achieved at the very thin thickness of 98 microns, which will have significant implications in terms of cost reduction, as Panasonic sets itself apart from other companies by continuing to improve efficiency of its solar cells while lowering costs.
Core technologies behind the record efficiency rating
- Reduction in recombination loss
A key feature of HIT solar cells is the lamination of a high-quality amorphous silicon layer onto the surface of the monocrystalline silicon substrate that serves as the power-generating layer. To further enhance this unique property of HIT cells, Panasonic has developed a new technology that enables an amorphous silicon layer of even higher quality to form on the monocrystalline silicon substrate while limiting damage to the surface of the substrate. This has enabled a further reduction or recombination losses within the carrier. As a result, the open voltage (Voc) has been improved from 0.748 V to 0.750 V
- Reduction in optical loss
Panasonic has successfully reduced absorption loss of light in the transparent conductive coatings and the amorphous silicon layer covering the monocrystalline sillicon substrate. At the same time, shading loss has also been decreased by reducing the surface area of the grid electrode on the cell surface. As a result, density of the short-circuit current (Isc) has been improved from 38.9 mA/cm^2 to 39.5 mA/cm^2
- Reduction in resistive loss
Panasonic has succeeded in cutting down resistive loss that occurs when an electric current passes through the grid electrode by improving the grid electrode, including the development of an electrode with a higher aspect ratio. As a result, the fill factor (FF) has been improved from 0.822 to 0.832