American institute of physics presents us more economical Selenium

Did you know that many researchers would like to find light-catching
materials in order to transform more of the sun's energy into carbon-free
electric power?

A new study described in the magazine Applied Physics Letters in August
2010 (published by the American Institute of Physics), describes how solar
energy could potentially be collected by using oxide materials that
include the element selenium. A team at the Lawrence Berkeley National
Laboratory in Berkeley, California, embedded selenium in zinc oxide, a
relatively low-cost component that could make more efficient use of the
sun's power.

The team determined that even a relatively small level of selenium, just
nine per-cent of the mostly zinc-oxide base, significantly increased the
material's performance in absorbing light.

The main author of this study, Marie Mayer (a fourth-year University of
California, Berkeley doctoral student) says that photo-electrochemical
water splitting, that signifies using power from the sun to cleave water
into hydrogen and oxygen gases, could possibly be the most exciting future
application for her efforts. Utilizing this reaction is key to the
eventual generation of zero-emission hydrogen powered vehicles, which
hypothetically will run only on water and sunlight.

Journal Reference: Marie A. Mayer et all. Applied Physics Letters, 2010

http://link.aip.org/link/APPLAB/v97/i2/p022104/s1

The conversion performance of a PV cell is the proportion of sunlight
energy that the solar cell converts to electrical energy. This is very
important when discussing Photo voltaic products, because improving this
efficiency is vital to making Photo voltaic electricity competitive with
more standard sources of energy (e.g., non-renewable fuels).

For comparison, the earliest Photovoltaic units converted about 1%-2% of
sunlight power into electrical energy. Today's Photovoltaic devices
convert 7%-17% of light energy into electrical energy. Of course, the
other side of the equation is the money it costs to manufacture the PV
devices. This has been improved over the decades as well. In fact, today's
PV systems make electricity at a fraction of the cost of early PV systems.

In the 1990s, when silicon cells were twice as thick, efficiencies were
much lower than today and lifetimes were reduced, it may well have cost
more energy to produce a cell than it could generate in a lifetime. In the
meantime, the technological know-how has progressed substantially, and the
energy repayment time (defined as the recovery time needed for generating
the energy spent to make the respective technical energy systems) of a
modern photovoltaic module is commonly from 1 to 4 years depending on the
module type and location.

Normally, thin-film technologies - despite having comparatively low
conversion efficiencies - achieve substantially shorter energy payback
times than traditional systems (often < 1 year). With a common lifetime of
20 to 30 years, this signifies that contemporary photo voltaic cells are
net energy producers, i.e. they produce significantly more energy over
their lifetime than the energy expended in producing them.

The author - Rosalind Sanders writes for the swiming pool solar covers blog, her personal hobby website focused on tips to help home owners to save energy with solar energy.