SEPTEMBER 6, 2004
Another Dawn For Solar Power
Tech breakthroughs and high energy
prices are rekindling the industry
By Otis Port in New York
a sunny june day in 1979, President Jimmy Carter
held the first and only press conference on the
White House roof. Atop the West Wing, he unveiled
a $28,000 solar cell system that captured the sun's
energy to provide hot water for the White House.
He also launched a sweeping drive aimed at harnessing
the sun, the wind, and other renewable resources
to generate 20% of America's electricity by 2000.
It didn't happen, of course. The share of electricity produced by solar cell
technology in the U.S. last year was a mere 0.07%. Carter's solar water-heating
system was removed in 1986 so a leak in the roof could be fixed. The solar panels
were supposed to be reinstalled but they never
Now, several startups aim to revive Carter's dream of harvesting the sun's rays.
Even the optimists admit it will take years to build enough solar energy capacity
to make a dent in coal and natural-gas consumption. But with better technology,
new solar systems could start plugging the power supply gap during periods of
peak demand in some
regions by 2007.
There are two basic concepts for tapping the sun's energy: collect its heat or
convert its light. The solar-thermal approach uses mirrors to reflect the heat
energy from a large area onto a small space, such as a pipe filled with a fluid
like molten salt. Once the fluid's temperature has been raised to hundreds of
degrees, it can be used to boil water
and produce steam for a conventional generator.
With the other approach, called photovoltaics, a semiconductor -- typically silicon
-- absorbs the photons streaming from the sun and reacts by giving off a flow
of electrons, or electricity.
techniques have been around for ages, but they
have made little headway in the U.S. because of
cheap fossil fuels. In Japan and Europe, where
such fuels aren't so cheap, unit sales of solar
energy systems have been mushrooming 35% annually
since the mid-1990s. Now, the combination of rising
fuel costs and engineering advances that boost
the efficiency of solar power systems are stimulating
The solar-thermal strategy is roughly 30% efficient at turning the sun's heat
into electricity -- about double the efficiency of photovoltaics. As a result,
the thermal technique enjoys a pricing advantage. The giant solar-dish mirrors
designed by Stirling Energy Systems Inc. could generate electricity for less
than 8 cents per kilowatt hour (kwh) -- maybe even 6 cents, asserts David J.
Slawson, CEO and founder of the Phoenix startup. Unlike photovoltaic panels,
though, solar dishes aren't practical for homes. To work effectively, they need
to be large -- too big to plant on a roof or even in a backyard. Stirling Energy's
dishes are 38 feet across and 40 feet tall and generate 25 kilowatts, or enough
juice for five or more homes.
The dishes are based on technology pioneered at the Solar Two "farm" in California's
Mojave Desert, sponsored by the Energy Dept. Mothballed in 1999, Solar Two used
1,800 solar dishes in concentric arcs to reflect
the sun's heat onto a central "power tower." That layout required a massive $150
million investment for 10 megawatts of capacity -- or $15 per watt. To reduce
costs with a modular approach, Slawson has scrapped the tower. Instead, he mounts
a miniature generator at the focal point
of each dish.
When these power dishes enter volume production, expected around the end of 2006,
Slawson predicts costs will tumble 90%, to $25,000 per 25-kilowatt dish. That
would put the capital cost of a 10-Mw plant at $10 million, or $1 per watt. But
Arizona Public Service Co., which is under a state mandate to generate 1.1% of
its electricity through renewable resources by 2007, isn't waiting. It will install
10 dishes next year. And utilities in Nevada and California are haggling for
On the photovoltaics front, upstart Solaicx Inc. in Los Gatos, Calif., predicts
that residential and commercial solar panels made with its silicon material will
soon compete with conventional fossil-fuel generators in markets where electricity
costs at least 10 cents per kwh. But for that to happen, the capital cost of
solar cell systems needs to reach the same magic number of $1 per watt of generating
capacity. That up-front investment, along with operating efficiency and equipment
depreciation, determines the price at which kilowatt-hours of output can be sold.
Today, the installed cost of high-efficiency silicon solar panels starts at $3
per watt. "Our customers should get
to $1 a watt by 2007," declares Robert S. Ford, CEO of Solaicx. Around 2010,
the Energy Dept. expects improved solar cells to generate electricity at 6 cents
Solaicx won't begin shipping silicon
from its new factory until October, but Ford claims
that two top producers of solar panels -- he won't
say which ones -- have already signed up to buy the
silicon platters. So has SunPower Corp. in nearby
Sunnyvale, Calif. A solar panel typically has 36 solar
cells carved from compact-disk-size silicon wafers.
Solaicx will churn out the wafers with equipment similar
to that used to make raw silicon for the semiconductor
industry -- but tailored from scratch for high-volume
production. "It's just good old-fashioned silicon
done right," says John T. Sedgwick, co-founder of
Solaicx uses two tricks to produce better solar cells:
make the silicon wafers 40% thinner and thus cheaper,
and increase something called carrier lifetime. When
photons from the sun hit the surface of a solar cell,
they dislodge electrons from silicon atoms. The longer
these electrons remain free -- the carrier lifetime,
measured in milliseconds -- the greater the chance
that they will stream off the solar cell "and into
your toaster or light bulb," says J. William Yerkes,
chief technology officer of Solaicx and a photovoltaics
pioneer for three decades.
With today's silicon, roughly 16 of every 100 bumped-off
electrons make it out into the real world, Yerkes
says. That means the cells are 16% efficient at turning
sunlight into electricity. By boosting carrier lifetime,
Solaicx' lower-cost wafers have yielded prototype
solar cells that are 21% efficient.
Silicon-based solar cells represent 92% of today's
photovoltaics market, but some producers are betting
on different, much cheaper materials for the future.
One is a conductive polymer salted with nano-size
carbon molecules dubbed buckyballs. Last year, researchers
at Germany's Siemens Solar Group (now Shell Solar)
applied a very thin coating of the buckyball mixture
on a plastic film and produced a solar cell that topped
5% efficiency -- the best yet for an organic solar
cell. The cost of these solar cells would be a fraction
that of their silicon cousins, so a homeowner could
buy five or ten times the surface area and still save
Despite its modest cost, the low output may limit
initial applications to fold-up recharging pads for
laptop computers and other portable gadgets. But the
researchers are confident that efficiency can be hiked
to 7%, or perhaps 10%. Then the solar coating applied
to a roof could supply all the required electricity
to a home.
Turning rooftops into power plants is also a focus
of newcomers on opposite coasts. Nanosys and Nanosolar,
both in Palo Alto, Calif., and Konarka Technologies
in Lowell, Mass., are developing liquid-plastic compounds
that can be applied to most surfaces. But instead
of buckyballs, they spice the mixture with nano-size
semiconducting wires or pinheads called quantum dots.
Japanese giant Matsushita Electric Industrial Co.
(MC) has teamed up with Nanosys to develop solar coatings
that could be painted on roofs and walls. Commercial
products are still a couple of years off. Konarka
echoes that timetable for its solar roof technology,
but recharging pads and solar energy coatings for
Army tents could be ready next year.
A Midwest company, Energy Conversion Devices Inc.
(ENER)'s United Solar Ovonic unit in Auburn Hills,
Mich., grabbed the early lead in solar roofs. Since
1997, it has been applying silicon coatings on roofing
materials. Its solar film can also be supplied as
peel-and-stick rolls, and these will be used on the
roof of Beijing New Capital Museum in China.
Thanks to the revolution in materials science wrought
by nanotechnology and conducting plastics, organic
solar coatings are also under development at such
industrial stalwarts as General Electric Co. (GE)
and IBM (IBM). And organic solar cells are the focus
of a new 4.6 million euro, 30-month research effort
in Europe. Called Molycell, its goal parallels what
Solaicx and Stirling Energy promise: solar power systems
with a capital cost of $1 per watt. France's atomic
energy agency heads the Molycell team. Konarka, Siemens,
and a half-dozen universities and energy research
centers are participating.
While the U.S. is still a major player in solar research,
it has fallen behind in reaping profits from solar
cells. Japan is way ahead of every other country.
In 2001, its annual capacity was nearly four times
that of America's 167.8 Mwp -- the p means peak, or
no cloudy days -- and Germany was a solid No. 2, with
260.6 Mwp. Last year, Japan generated half of all
the world's solar power, built 44% of all new solar
energy equipment, and installed five time as much
new solar power capacity as the U.S. One company,
Sharp Corp. (SHCAY ), accounted for 27% of all new
solar panels, according to market researcher PV Energy
Systems Inc. in Warrenton, Va.
Worldwide, unit shipments of solar systems have jumped
35% or more for each of the last eight years. Include
installation costs, and market researcher Clean Edge
Inc. pegs solar industry sales at $4.7 billion in
2003. For 2013, the Oakland (Calif.) company sees
solar topping $30.8 billion.
However, that projection is based on installed per-watt
costs remaining way above $1. If Solaicx, Stirling
Energy, and Molycell deliver solar generation for
$1 a watt by 2007, the business of harnessing the
sun's energy could go supernova.