By Rosalind Sanders
Scientists at the American Institute of Physics are seeking to identify superior light-catching substances in order to better transform more of the sun's power into carbon-free electric power. And their learned labors are now bearing fruit that could change the way the world gets its energy forever: cheaper, faster and less harmfully to the environment.
A new study in Applied Physics Letters (published by the American Institute of Physics) describes how solar energy could potentially be collected by using oxide materials that have the element selenium. A team at the Lawrence Berkeley National Laboratory in Berkeley, California, inserted selenium in zinc oxide, a relatively low-priced component that could make more cost-efficient use of the sun's power.
The research team determined that even a relatively small level of selenium, just nine per-cent of the mostly zinc-oxide base, dramatically enhanced the material's performance in absorbing light.
The principal author of this analysis, Marie Mayer (a fourth-year College of California, Berkeley doctoral student) says that photo-electrochemical water splitting, that signifies employing energy from the sun to cleave water into hydrogen and oxygen gases, could potentially be the most revolutionary future application for her work. Using this reaction is key to the eventual creation of zero-emission hydrogen powered automobiles, which hypothetically will run only on water and sunlight.
The conversion effectiveness of a PV cell is the proportion of sunlight energy that the solar cell converts to electricity. This is very important when discussing Photovoltaic products, because boosting this efficiency is vital to making Pv electricity competitive with more standard sources of energy (e.g., fossil fuels).
For comparison, the very first Photovoltaic products converted about 1%-2% of sunlight power into electric energy. Today's Pv devices convert 7%-17% of light energy into electric power. Of course, the other side of the equation is the dollars it costs to make the PV devices. This has been reduced over the years as well. In fact, today's PV systems generate electricity at a fraction of the cost of first PV systems.
In the 1990s, when silicon cells were twice as thick, efficiencies were much smaller 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 significantly, and the energy repayment time (defined as the recovery time required for generating the energy spent to produce the respective technical energy systems) of a modern photovoltaic module is normally from 1 to 4 years depending on the module type and location.
Normally, thin-film technologies - despite having comparatively low conversion efficiencies - obtain considerably shorter energy repayment times than standard systems (often < 1 year). With a normal lifetime of 20 to 30 years, this signifies that current solar cells are net energy producers, i.e. they generate significantly more energy over their lifetime than the energy expended in producing them.
Rosalind Sanders is the publisher of, and writes for, The Solar Panel Review, which focuses on helping homeowners reduce expenses with solar energy.
