Panasonic HIT(R) Solar Cell Achieves World's Highest Conversion Efficiency of 24.7% at Research Level
September 1, 2014     Japanese 
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Panasonic HIT(R) Solar Cell Achieves World's Highest Conversion Efficiency of 24.7% at Research Level - JCN Newswire
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Panasonic HIT(R) Solar Cell Achieves World's Highest Conversion Efficiency of 24.7% at Research Level

Osaka, Feb 12, 2013 - (JCN Newswire) - Panasonic Corporation today announced it has achieved a record conversion efficiency of 24.7%(1) at the research level, using its HIT(R) solar cell at 98 micro-m thickness. The rate is the world's highest(2) for any crystalline silicon-based solar cell of practical size (100 cm2 and above).

This record conversion rate demonstrates superb efficiency of Panasonic HIT solar cells to convert sunlight into electricity. The latest figure is 0.8 percentage points higher than the previous record (23.9%) for HIT solar cells, and 0.5 percentage points higher than the previously published record(3) for any monocrystalline silicon-based solar cell of practical size (100 cm2 and above).

Further, achieving this high efficiency at the very thin thickness of 98 micro-m has significant implications in terms of cost reduction as Panasonic continues to improve efficiency of its solar cells while lowering costs, with the aim to set itself apart from other companies in the industry.

- Core technologies behind the record efficiency rating

(1) 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. This leads to a reduction in recombination loss(4) within the electrical elements, known as carriers(5). To further enhance this unique property of HIT solar cells, Panasonic has developed a new technology that enables to form on the monocrystalline silicon substrate an amorphous silicon layer of even higher quality while limiting damage to the surface of the substrate. This has enabled a further reduction of recombination losses within the carrier. As a result, the open voltage (Voc)(6) has been improved from 0.748 V to 0.750 V.

(2) Reduction in optical loss
In order to achieve a high electrical current from solar cells, it is necessary to induce the solar rays arriving at the cell surface into the monocrystalline silicon substrate that serves as the power-generating layer with as little losses as possible. This time, using a HIT solar cell, Panasonic has successfully reduced absorption loss of light in the transparent conductive coatings and the amorphous silicon layer covering the monocrystalline silicon 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 (Jsc)(7) has been improved from 38.9 mA/cm2 to 39.5 mA/cm2.

(3) Reduction in resistive loss
In solar cells, the electrical current generated is accumulated within the grid electrode on the cell surface and then delivered outside. This time, 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(8). As a result, the fill factor (FF)(9) has been improved from 0.822 to 0.832.

Panasonic will focus on applying this newly-developed high-efficiency technology to mass production products, and will continue to develop technologies that improve efficiency, reduce costs, and save resources further.

- Properties of HIT solar cells

-- Open voltage (Voc) 0.750 V
-- Short-circuit current (Isc) [short-circuit current density (Jsc)](7) 4.02 A [39.5 mA/cm2]
-- Fill factor (FF)(9) 0.832
-- Cell transfer efficiency 24.7%
-- Cell surface area 101.8 cm2

Diagram available at http://panasonic.co.jp/corp/global/news_m.html.

(1) As evaluated by the National Institute of Advanced Industrial Science and Technology
(2) As of February 12, 2013 (Panasonic survey)
(3) As determined from "Solar cell efficiency tables (version 41)" [Prog. Photovolt: Res. Appl. 2013; 21:1-11]
(4) Recombination loss refers to a reduction in current and voltage output from the solar cell caused by positive and negative electrical charge (carriers) generated within the solar cell then combining within the solar cell and thus cancelling out.
(5) Carriers are comprised of two types of electrical particles-electrons (negative) and holes (positive). While electrons carry a negative charge, holes are effectively empty shells without electrons and thus carry a positive charge.
(6) Open voltage (Voc) is the maximum voltage generated by the solar cell. Short-circuit current density (Jsc) is calculated by dividing Isc by the surface area of the cell.
(7) Short-circuit current (Isc) is the maximum current generated by the solar cell.
(8) A higher aspect ratio refers to a higher ratio of height to line width within the grid electrode. Since the grid electrode serves to block light entering the cell surface, a higher aspect ratio serves to reduce such losses and to lower resistance within the electrode grid.
(9) Fill factor (FF) is a value calculated by dividing the maximum output of the solar cell by the product of the open voltage and short-circuit voltage.

About Panasonic

Panasonic Corporation is a worldwide leader in the development and engineering of electronic technologies and solutions for customers in residential, non-residential, mobility and personal applications. Since its founding in 1918, the company has expanded globally and now operates over 500 consolidated companies worldwide, recording consolidated net sales of 7.30 trillion yen for the year ended March 31, 2013. Committed to pursuing new value through innovation across divisional lines, the company strives to create a better life and a better world for its customers. For more information about Panasonic, please visit the company's website at http://panasonic.net/ .

Contact:

Panasonic Corporation
Tokyo Public Relations Office
Tel: +81-3-3574-5664
Fax: +81-3-3574-5699
 


Feb 12, 2013
Source: Panasonic

Panasonic (TSE: 6752) (U.S: PC)

From the Japan Corporate News Network
http://www.japancorp.net
Topic: Research and development
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