Did you know that many researchers would like to identify light-catching materials in order to transform more of the sun's energy into carbon-free electrical energy?
A new research announced in the magazine Applied Physics Letters in August this year (written and published by the American Institute of Physics), explains how solar energy could potentially be harvested 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 cheap component that could make more successful use of the sun's power.
The team identified that even a relatively small quantity of selenium, just nine percent of the mostly zinc-oxide base, dramatically increased the material's performance in absorbing light.
The principal author of this analysis, Marie Mayer (a 4th-year College of California, Berkeley doctoral student) reveals that photo-electrochemical water splitting, that signifies using power from the sun to cleave water into hydrogen and oxygen gases, could probably be the most interesting future application for her efforts. Harnessing this reaction is key to the eventual creation of zero-emission hydrogen powered automobiles, which hypothetically will run only on water and sunlight.
Journal Research: Marie A. Mayer et all. Applied Physics Letters, 2010
The conversion efficiency of a PV cell is the amount of sunlight energy that the photovoltaic cell converts to electrical power. This is very important when discussing Photo voltaic products, because boosting this efficiency is vital to making Photo voltaic energy competitive with more standard sources of energy (e.g., non-renewable fuels).
For comparison, the initial Photovoltaic devices converted about 1%-2% of sunlight energy into electrical energy. Today's Photovoltaic products convert 7%-17% of light energy into electric power. Of course, the other side of the equation is the dollars it costs to manufacture the PV devices. This has been improved over the years as well. In fact, today's PV systems produce electricity at a fraction of the cost of early PV systems.
In the 1990s, when silicon cells were 2 times as thick, efficiencies were much lower than these days 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 innovation has moved on considerably, and the energy repayment time (defined as the recovery time necessary for generating the energy spent to make the respective technical energy systems) of a modern photovoltaic module is generally from 1 to 4 years depending on the module type and location.
Normally, thin-film technologies - despite having relatively low conversion efficiencies - obtain considerably shorter energy repayment times than traditional systems (often < 1 year). With a typical lifetime of 20 to 30 years, this signifies that modern photo voltaic cells are net energy producers, i.e. they generate significantly more energy over their lifetime than the energy expended in producing them.
Rosalind Sanders shares knowledge for the solar covers blog, her personal hobby weblog centered on suggestions to help home owners to save energy with solar power.
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