Thin-film is rapidly becoming the solar cell technology of
choice, replacing the established crystalline technology, according
to analysts iSuppli.
Thin-film solar cells will take 31% of the 2013 global solar
panel market measured in watts, an increase of 14% on thin-film's
share of the solar cell market in 2008.
"The market viability of thin-film has been solidly established
by First Solar Inc. as it rockets to become the world's top solar
panel maker this year, with more than a gigawatt of production,"
says Greg Sheppard, chief research officer for iSuppli, "at the
same time, the company has driven its cost of production to less
than 90c per watt, keeping its costs at approximately half the
level of crystalline module producers."
Most solar panels are made of crystalline wafers with 180 to 230
microns of polysilicon. In contrast, thin-film panels are made by
depositing multiple layers of other materials a few micrometers in
thickness on a substrate.
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Electronics Weekly focus on solar cells
The main trade-off between the two technologies is efficiency
versus cost per watt of electricity generation. Thin-film panels
are less efficient at converting sunlight to electricity, but they
also cost significantly less to make.
At the same time, thin-film is at a disadvantage when
installation space is limited, such as on a residential rooftop. A
thin-film installation can take 15% t to 40% more space to achieve
the same total system wattage output as crystalline. This tends to
limit its appeal in certain applications.
The average thin-film solar panel price is expected to decline
to $1.40 in 2010, down 17.6% from $1.70 in 2009.
Average prices for crystalline panels are expected to drop to
$2.00 in 2010, down 20% from $2.50 this year.
Through 2012, crystalline prices will continue to close the
thin-film pricing gap to some degree because its purveyors
collectively have deeper pockets and are maintaining their capex,
R&D spend and manufacturing improvements, says iSuppli.
Many types of thin-film PV technologies are available. Their
efficiencies in converting light to electricity mostly hover at
less than 10%, although some have lab results pushing into the
mid-teens.
Some of these technologies are what is known as single-junction,
where one diode is used. Recent developments use multiple junctions
stacked on top of one another-also called tandem and triple
junction-so that more parts of the spectrum can be absorbed using
different combinations, or junctions, of material.
Most of these technologies rely on variants of Chemical Vapour
Deposition (CVD), or screen printing, to deposit the layers of
materials on various substrates, i.e., glass and various plastics.
Some recent technologies employ variants of ink-jet printing to
more quickly deposit the materials.
Another accelerator of thin-film technology is the rising
availability of turn-key production lines from companies such as
Applied Materials, Oerlikon, and Centrotherm.