"American institute of physics illustrates us more cost-efficient Selenium pv cells"

Did you know that many scientists would like to discover light-catching elements in order to transform more of the sun's energy into carbon-free electrical power?

A new research described 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 include the element selenium. A team at the Lawrence Berkeley National Laboratory in Berkeley, California, inserted selenium in zinc oxide, a relatively economical component that could make more productive use of the sun's power.

The team identified that even a relatively small amount of selenium, just nine per cent of the mostly zinc-oxide base, considerably increased the material's effectiveness in absorbing light.

The main author of this research, Marie Mayer (a 4th-year College of California, Berkeley doctoral student) says that photo-electrochemical water splitting, that signifies employing power from the sun to cleave water into hydrogen and oxygen gases, could potentially be the most exciting future application for her work. Managing 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 [link: http://link.aip.org/link/APPLAB/v97/i2/p022104/s1]

The conversion efficiency of a PV cell is the portion of sunlight energy that the photovoltaic cell converts to electricity. This is very important when discussing Pv devices, because improving this efficiency is vital to making Pv electricity competitive with more conventional sources of energy (e.g., non-renewable fuels).

For comparison, the 1st Photovoltaic devices converted about 1%-2% of sunlight energy into electric energy. Today's Photovoltaic systems convert 7%-17% of light energy into electric energy. Of course, the other side of the equation is the dollars it costs to produce the PV devices. This has been enhanced over the years as well. In fact, today's PV systems generate 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 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 technology has developed a lot, and the energy repayment time (defined as the recovery time needed for generating the energy spent to produce the respective technical energy systems) of a modern photovoltaic module is commonly from 1 to 4 years depending on the module type and location.

Generally, thin-film technologies - despite having reasonably low conversion efficiencies - achieve considerably shorter energy repayment times than traditional systems (often < 1 year). With a typical lifetime of 20 to 30 years, this signifies that contemporary solar cells are net energy producers, i.e. they generate significantly more energy over their lifetime than the energy expended in producing them.

About the author - Rosalind Sanders gives advice for the solar covers review blog, her personal hobby blog focused on guidelines to help home owners to save energy with solar power.