American institute of physics displays us more effective Selenium photo voltaic cells

by Rosalind Sanders

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

A new study described in the magazine Applied Physics Letters in August this year (released by the American Institute of Physics), explains how solar energy could potentially be collected by using oxide elements that include the element selenium. A team at the Lawrence Berkeley National Laboratory in Berkeley, California, inserted selenium in zinc oxide, a relatively affordable substance that could make more effective use of the sun's power.

The team discovered that even a relatively small quantity of selenium, just nine % of the mostly zinc-oxide base, significantly increased the material's effectiveness in absorbing light.

The primary author of this study, Marie Mayer (a 4th-year College of California, Berkeley doctoral student) states that photo-electrochemical water splitting, that signifies employing power from the sun to cleave water into hydrogen and oxygen gases, could possibly be the most fascinating future application for her efforts. Utilizing 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 link: http://link.aip.org/link/APPLAB/v97/i2/p022104/s1

The conversion effectiveness of a PV cell is the percentage of sunlight energy that the photo voltaic cell converts to electricity. This is very important when discussing Photo voltaic products, because enhancing this efficiency is vital to making Photo voltaic power competitive with more conventional sources of energy (e.g., non-renewable fuels).

For comparison, the very first Photo voltaic products converted about 1%-2% of sunlight power into electrical energy. Today's Photo voltaic products convert 7%-17% of light energy into electrical power. Of course, the other side of the equation is the dollars it costs to produce the PV devices. This has been enhanced over the decades 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 two times as thick, efficiencies were much smaller than these days and lifetimes were reduced, it may well have cost more energy to create a cell than it could generate in a lifetime. In the meantime, the technological know-how has developed considerably, 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 usually from 1 to 4 years depending on the module type and location.

Usually, thin-film technologies - despite having relatively low conversion efficiencies - obtain considerably shorter energy repayment 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.

About the writer - Rosalind Sanders publishes articles for the www.poolsolarpanels.org/solar-covers swiming pool solar covers blog, her personal hobby weblog focused on recommendations to help home owners to spend less energy with solar energy.