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With their lower-cost
manufacturing methods and freedom from silicon shortages, thin-film
solar cell technologies have occupied a growing slice of market share,
and a great deal of buzz continues to surround amorphous silicon
(a-Si), in particular.
But considering that the popularity of
thin film was so tightly linked to the limited availability of the
polysilicon and silane required for the manufacture of crystalline
wafer cells, what is in store for a-Si now that supply shortages no
longer constrain the silicon wafer market?
"Because there is a
plentiful supply of polysilicon and silane in the supply chain now, it
will greatly slow down what people were anticipating would be fast
growth for amorphous silicon," says Lita Shon-Roy, senior managing
partner at market research firm Techcet Group LLC.
Both the
solar market's overall slowdown and polysilicon providers' expanded
capacities contributed to the current polysilicon oversupply, which
Shon-Roy expects will last for the next few years.
Typical
contract prices for silicon have plummeted from approximately $180 per
kg to $110 per kg, with spot pricing even lower. Although existing
contracts have prevented many wafer manufacturers from reaping the
benefits of the price drops, contract renegotiations are becoming
increasingly popular, she adds. Other manufacturers are opting to buy
silicon on the open market for an astounding $50 per kg.
As a
result of this enormous shift, market share for a-Si, which is
currently in the single digits, is now generally expected to remain
well below 20% for the next five years.
In addition, low
conversion efficiency, which was previously often viewed as the most
potent growth-limiting factor for a-Si and other thin-film
technologies, might now rank as the less important concern.
However,
Shon-Roy notes that although a-Si manufacturers certainly still face
challenges in increasing efficiency, many companies have made notable
strides recently.
"Conversion efficiencies today are somewhere
between six percent and eight percent in actuality, but manufacturers
should be able to reach upwards of 12 percent to 15 percent in the next
five years," she says.
Market-penetration advantages will likely
be realized once several a-Si cell manufacturers cross that 12% to15%
threshold. "But depending on how you do the math, even at 10 percent
efficiency, the technology can still work less expensively than silicon
wafer-based technology," she adds.
Nonetheless, Shon-Roy says
a-Si boasts the most cost-reduction potential of the major thin-film
technologies. As was the case in the semiconductor industry, this
distinguishing quality is likely to prove even more important as the
solar cell manufacturing industry grows, and will help propel a-Si's
expansion.
Cadmium telluride solar cells, in contrast, currently
hold about 5% of current market share and may gain another 5% over the
next five to six years. This technology's growth, however, remains
"somewhat limited" because of innate technological shortcomings and a
toxicity stigma, says Shon-Roy.
In addition, "From a
supply-chain standpoint, cadmium and tellurium are metals that are not
as abundant in availability as materials like aluminum and silicon,"
she says.
Generally, within a-Si and beyond, thin-film
manufacturers that can smartly engage in materials substitution can be
reasonably expected to thrive in the new market. "The name of the game
for thin-film production is that the materials that are going to be
used need to be relatively available and inexpensive," Shon-Roy
stresses.
Thin-film cells originally incorporated indium tin
oxide as the transparent conductor, for example. This material was
subsequently replaced with more readily available and less expensive
aluminum zinc oxide, she points out. Although a similarly obvious
replacement may not be found again, the quest for such measures remains
ever-important.
Meanwhile, as a-Si manufacturers grapple with
the new market challenges associated with the silicon glut, an old and
formidable hurdle still lingers.
"I think the biggest obstacle
for amorphous silicon is its track record," Shon-Roy says. With few
completed installations in the field in comparison to other
technologies, and relatively short operating histories for most of
these existing systems, many utilities and other key purchasers remain
wary of a-Si, despite what is generally a lower price tag.
But
ultimately, inevitable gaps between lab performance and performance in
the field - a classic developing-technology issue to which a-Si has not
been immune - can be overcome and help boost a-Si's reputation.
According
to Shon-Roy, one recent study showed that the majority of lab-developed
technologies will attain 80% of their laboratory results once they
reach wide-scale high-volume production, and that any technology takes
at least five years before it approaches the upper end of what it can
achieve.
