CIS-Solar Cells From the Assembly
Line:
Pilot Factory for Thin Layer Modules Starts Production
A new chapter in solar technology history is being
written in Marbach on Neckar. The Würth Solar GmbH and Co.
KG opened their pilot factory to manufacture CIS Thin Layer Solar
Modules on June 19, 2000 .
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Technology Park Marbach. Location
of the CIS pilot factory from Würth Solar.
Thin layer modules with an entire surface area of 10,000 square
meters will be manufactured here.
Illustration: Würth Solar
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The new technology allows the rational production of high quality
and long lasting solar cells with low material and energy expenditures.
The important features of the product line are efficiency, quality
and versatility. Würth Solar wants to bring the first CIS modules
on the market as soon as August 2000.
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CIS: High Tech for a Sunny Future
The thin layer cells are made predominately out of the elements
copper, indium and selenium. The chemical symbol is CuInSe2.
In comparison to the well-known, shiny blue, polycrystalline silicon
cell, which features a 12-14% rate of efficiency, the material and
energy production expenses are considerably lower.
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Structure of a CIS solar cell.
Illustration: Würth Solar
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Uses for CIS cells
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CIS cells are ten times thinner than polycrystalline cells.
Their photo active layer is deposited directly on pieces of standard
window glass. Just like the red-brown amorphous silicon cells- which
are found in calculators and clocks- the CIS cells are produced
in thin, material-saving layers. However, the CIS cells considerably
outperform the efficiency of standard amorphous silicon cells on
an average of 6 percent: in the laboratory of the Center for Sun
Energy and Hydrogen Research (Zentrum für Sonnenenergie- und
Wasserstoff-Forschung-ZSW) at the University of Stuttgart, a square
CIS module with a length of 30 centimeters achieved almost 13% efficiency.
That is the current "world record".
Elements are being produced in the new factory that measure 60 by
120 centimeters. The manufacturer wants to raise the efficiency
from the current 8 percent to 10, and later even to12 percent. Bernhard
Dimmler, technical manager of Würth Solar, has calculated a
yearly output of at least 1.2 megawatts of power during the pilot
phase. That would conform with approximately 10,000 square meters
of module surface, or the electricity consumption of 300 households.
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The Turning Point: Solar Technology Production
in a Former
Coal-Fired Power Station
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The cooperative project from Würth Solar, the EnBW Kraftwerk
AG and the ZSW is pointing the way into the future. Using former
buildings from the EnBW and in cooperation with the city of Marbach,
a model project was developed to convert a power station site. 11
other companies will be active in the future energy and technology
park, next to the solar factory, which first gave it momentum.
Solar modules will now be built, where fossil resources once burned.
A project on fuel cell technology will also be represented. The
technology of yesterday is giving way to the technology of tomorrow.
The generators in the former boiler room of the coal-fired power
station Marbach I have been shut down. Instead, Würth solar
cells are being manufactured here in dust-free rooms.
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The system for manufacturing the CIS module being
delivered to the boiler room in the former coal-fired power station.
Illustration: Würth Solar
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The company sees itself as a development partner and know-how supplier
for photovoltaic producers who want to solve system problems with
CIS technology. Würth Solar intends to invest approximately
30 million marks in the project; the system technology alone already
costs 18 million marks. Another 12 million marks are furthermore
estimated for the reconstruction of the building and running costs.
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Würth Solar's competative edge is exhibited by their achievement
of the layering of a one-thousandth of a millimeter thin light sensitive
film. Up until then, CIS cells were layered and alloyed in several
steps. At Marbach, this step takes place in one process: copper,
indium, and selenium are vaporized at the same time under absolute
vacuum conditions at 500° Celsius. The elements then adhere
to a plate of two to four millimeter thick window glass, that has
already been coated with a backing pin of the metal molybdenum.
The layers are then "apportioned" with laser beams and
then fixed to the desired tension. Afterwards a transparent contact
layer of zinc oxide is applied, the module is then packed between
the treated and an untreated glass plate. Sealed in this way, it
will be protected against environmental influences for a long time.
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The goal is to make solar energy marketable. Würth
solar is moving in a new direction.
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The CIS system in the dust-free room
Illustration: Würth Solar
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Bright Prospects for Photovoltaics
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Würth is expecting a considerable reduction in costs from
the mass production of thin layer modules. CIS modules should soon
be offered for much less than customary products. Photovoltaic has
already cleared most of the hurdles of profitability anyway. State
support and growing environmental awareness are boosting demand.
Lower prices would strengthen the trend for one's own solar power
station even more.
"We are deliberately investing in future technology, that we
regard as elementarily important. But as a company, we have, of
course, success as our aim," stated Rolf Bauer, who is responsible
for the solar company in the Würth corporation, at the inauguration
of the solar factory. Next to production, Würth Solar is also
striving for the worldwide distribution of portable systems. These
should come into use where no electrical grid is available, such
as in developing countries.
Illustrations and material: Würth
Solar GmbH & Co. KG. Red. Solarserver. Rolf
Hug
Translation: Mary Meier
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