Energy Conversion Records Continue To Be Broken

SANYO Electric has announced that it
has broken its own record for the world's highest energy conversion efficiency
in practical size (100 cm2 or more) crystalline silicon-type solar cells,
achieving a efficiency of 23.0% (until now 22.3%) at a research level for its
proprietary HIT solar photovoltaic cells. SANYO is pushing forward with the
expansion of its solar business, based on its Brand Vision ‘Think GAIA', and
aims to realize a clean energy society.  The increase in the solar cell conversion
efficiency this time is accompanied by significant advances in lowering the
production cost of the photovoltaic system and the reduction in the use of raw
materials such as silicon. This achievement by SANYO represents the first time
that a photovoltaic manufacturer has broken through the 23% mark in conversion
efficiency at the research-level for practical-sized solar cells, and further
cements the leadership of SANYO's HIT solar cell which is renowned for its high
conversion efficiency.

For now on
SANYO will continue to advance its efforts into applying this research-level
achievement into mass production, and promote further research into energy
efficiency, as well as reductions in cost and
materials.

*1         HIT (Heterojunction with Intrinsic Thin layer) solar cell is
composed of a single thin crystalline silicon wafer sandwiched by ultra-thin
amorphous silicon layers. This product provides industry-leading performance and
value using state-of-the-art manufacturing
techniques.

*2         As of May 22, 2009 (according to
in-house surveys)

*3         Evaluation results provided by the
National Institute of Advanced Industrial Science and Technology (AIST), an
energy conversion efficiency public certification
body

Overview of the elemental technology
enabling the high energy conversion efficiency

1. Improvement in the quality of
heterojunction *4 of HIT solar cell
(single-crystalline silicon (c-Si) and amorphous silicon
(a-Si))

The structure of the HIT solar cell
is such that it has a feature that can reduce recombination loss*5 of the
electrical element (charged carrier) *6 by surrounding the energy generation
layer of single thin crystalline silicon (c-Si) with high quality ultra-thin
amorphous silicon (a-Si) layers. SANYO has recently managed to improve the
quality of the HIT solar cell junction through developing a technology for
depositing a higher quality a-Si layer over the c-Si substrate while protecting
the c-Si surface from being damaged.
The result was an increase in the open
circuit voltage (Voc) *7 from 0.725V to 0.729V.

2. Reduction of optical absorption
loss

In the solar cell, sunlight that
hits its surface needs to be guided to the c-Si, the energy generation layer,
with the smallest possible absorption loss. As for the HIT solar cell, reduction
of optical absorption loss in the a-Si layer, which covers the front and rear
surfaces of the c-Si, and the transparent conductive layer was a challenge.
Absorption of short-wavelength solar radiation by the a-Si layer and that of
long-wavelength solar radiation by the transparent conductive layer were the
causes of the optical absorption loss. SANYO has recently developed know-how to
reduce optical absorption loss in both the a-Si layer and transparent conductive
layer. As a result, the short circuit current (Isc) *8
was improved from 39.2mA/cm2 to 39.5mA/cm2.

3. Reduction of resistance
loss

In the solar cell, generated
electric current is collected by and taken out through the surface grid
electrode. SANYO has recently realized lower-resistance electrode material for
use in the grid electrode and a higher-aspect ratio through improving printing
technology, leading to a success in reduction of resistance loss when an
electric current flows through the grid electrode. As a result, the fill factor
(FF) *9 was improved from 0.791 to 0.80.