Environmental Engineering Reference
In-Depth Information
Solar energy can be harvested either using photovoltaic (PV) cells that
convert the light directly into electricity or using solar thermal collectors.
The latter is much lower in capital cost and is far more efficient in that they
convert nearly half the impinging solar radiation into heat. Heat, however,
is a low-grade energy not as convenient to store or use as electricity.
Commercial efficiency of PV modules based on polycrystalline silicon (over
70% of modules produced in 2010) is approximately 14% (and 7-11% for
the newer thin-film modules) (U.S. Department of Energy (US DOE, 2011)).
Research cells under development show higher efficiencies, as much as
42% in a multijunction concentrator. The 3D solar PV panels still under
development can generate 20 times more energy compared to conventional
flat panels and are claimed to push the efficiencies close to the theoretical
maximum for silicon. Emerging printed electronic technologies are also
likely to soon deliver roll-to-roll production of flexible, fully printed solar
cells on plastics substrate.
The global installed PV capacity in 2010 stood at 40 GW with Europe, the
market leader, and the United States, a minor producer, with a capacity of
only 2.5 GW. The world's largest facility in Bavaria, Germany, produces 10
MW of electricity from its 3 acre solar farm. The capital cost of installed PV
cannot as yet effectively compete with fossil fuel energy; a robust PV farm
installed over less than 0.05% of Earth's surface should be able to generate
the annual fossil fuel energy budget of the world. Despite the low cost of
energy in the near future, solar energy technology is likely to grow into a
very significant player in the future energy markets around the world (
Fig.
1.6
).
