Light of the world—Building success as the solar industry goes global
fice buildings, warehouses and many other bus-bar, and top-side current-collector
locations.
“Historically low sales
layers. After the final printing stage, the
Screen printing is the process of choice cell is fired in a furnace. At the beginning
for PV cell production. The equip- volumes for PV panels of the line, a cassette loader delivers the
ment and processes are robust. Current
have warranted reliance
unprinted wafers into the first printer.
leading-edge equipment is easily capable Subsequent handling includes an automated
of meeting the accuracy and repeatability on bespoke equipment, inverter to allow printing on both sides of
requirements to produce PV cells at high
built to special order,
the wafer, and an unloader at the end of
yield rates. The typical requirements for the line to stack the completed PV cells
line width when depositing current collec- but with the transition ready for collection.
tors on a bulk-silicon PV array, for example,
is 100 microns. Some vendors of screen
to a high-volume global
Setting up a PV cell assembly facility
is barely more complex than buying and
printing solutions are able to achieve
market, capital
installing the production line. It can be
significantly greater accuracy. DEK, for ex-
ample, has a successful track record in the
equipment suppliers
commissioned as a standard, off the shelf,
turnkey installation. A typical modern
semiconductor packaging industry, and is
must make use of more
production line is rated at 1,200 units per
able to produce interconnects for chip-scale
packages using advanced screen printing
modern techniques.”
hour (UPH), allowing easy synchronisation
with other production activities. Predictable
capabilities. Conversely, screen printing performance allows users to scale produc-
is also effective to produce relatively thick tion easily to achieve the desired overall
deposits at high speeds. a sequence of printing and drying stages capacity expressed in megawatts. Screen
Screen printing also offers benefits in to create the bottom-side metallization, printing processes such as those
thin-film PV cell production. For example,
some emerging techniques to boost energy
conversion efficiency will require intricate
deposit patterns to produce multiple cell
types on a single substrate. These allow
the array as a whole to be sensitive to the
widest possible range of wavelengths and
thereby harvest more energy from light fall-
ing on the panel. Screen printing is able to
achieve complex deposit shapes to produce
these multi-cell arrays at lower cost than
other processes, such as vapour deposition
and jetting.
Accurate design and production of
stencils and emulsion screens is critical
to the success of screen printing in any
precision industrial application. PV cell
fabrication is no exception. A number
of technologies are applicable, including
laser-cut or electro-formed metal stencils as
well as emulsion screens created by etching
the required image in a fine, coated mesh.
These hold the key to producing a variety
of ultra-fine features, heavy deposits or
complex patterns in a single operation to
sustain continuous high throughput.
As consumer demand for solar panels
increases, the PV industry’s requirements
on resolution, repeatability, flexibility and
high-speed throughput are now expected
to increase more quickly than at any time
in the past. Increasingly, manufacturing
businesses will need to ensure that their
partners are able to deliver solutions that
not only meet current technical requirements
but also help them scale capacity quickly
and easily in response to rapid developments
in the market.
Turnkey production line
A generic PV cell production line comprises
www.globalsolartechnology.com Global Solar Technology – September/October 2008 – 21
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