Title
Solar energy—Photovoltaics
Dr. Jennie S. Hwang
H-Technologies group
Solar energy—Photovoltaics
To follow up with my last column in the conversion from light into electricity. Solar
inaugural issue on solar energy, let’s now “In contrast to other cells are essentially pn-junction diodes.
circumscribe the subject to photovoltaics
(PV). In using solar energy, PV is among
technologies, photo-
The conversion efficiency is built on
the photon absorption efficiency, photon-
the most viable and important technologi-
voltaics shines on its
to-electron conversion, the free path of
cal pathways. Currently, PV is experiencing
dynamic environments in both marketplace
intrinsic merit of direct
electrons and electron mobility, which in
turn are associated with the atom structure
and technological development.
conversion from light
and defects of the semiconductor films.
market dynamic
into electricity. ”
When the sunlight shines on the semi-
conductor solar panel, the light can be
Since the last writing, global events have reflected, pass through or be absorbed. The
evolved in a much divergent fashion, absorbed sunlight (photons) by the solar
including an unprecedented, tumultuous proportion and should not dictate PV solar panel is to be converted to electrons in the
financial debacle. To the momentum of energy development. atom structure of the semiconductor of the
photovoltaics, some events are viewed as It has long been a belief that the wide solar cell material, resulting in electrical
upward lifting, and some are downward deployment of photovoltaics relies on current in an electrical circuit. Since the
pressure. For example, EU countries’ gov- the government’s initiatives and financial solar energy spectrum covers a wide range
ernment incentives for solar energy, such incentives. Indeed, government plays a cru- of wavelengths from UV to infrared, low-
as in Germany and Spain, have reached a cial role in the adoption and application of energy photons will not be absorbed while
plateau or subsided while the long-awaited PV solar energy as an environment-friendly high energy photons will contribute only
solar energy tax incentives from the U.S. renewable energy source. Yet with or with- a portion of their energy to the electrical
government were finally incorporated in out the government’s engagement, how fast current. Any parasitic effects will limit the
the country’s financial bailout program, and to what extent the PV can contribute efficiency of the cell.
extending them for a period of eight years. to electricity generation in the U.S. and the Categorically, if we take the PV cell
Meanwhile, oil prices plummeted below world largely depends on two fronts: cost technology in three generations, they are
$70/barrel during the month of October. ($/W or $/Kwh) and technology. thick film/ bulk polycrystalline silicon,
Psychologically, the reduced oil price may thin film/amorphous silicon or other
dampen enthusiasm about renewable Technology dynamic substrates and nano-based or organic cells.
energy. Yet in reality, oil contributes to In contrast to other technologies, photovol- At the time of this writing, the thick film/
U.S. electricity generation in a miniscule taics shines on its intrinsic merit of direct bulk polycrystalline silicon, as the first
24 – Global Solar Technology – November/December 2008 www.globalsolartechnology.com
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