The Solar PowerFlower is a portable concentrated photovoltaic power generator intended for agricultural use.
It was designed by Jason Halpern, co-founder of PowerFlower Solar, who began developing the technology while still a student at the University of Pennsylvania.
Spain has overtaken the US as the biggest solar electricity generator in the world.
The opening of the new La Florida solar plant at Alvarado, Badajoz, in the west of the country, takes Spain’s solar output to 432 megawatts, compared with the US output of 422 megawatts.
The La Florida plant produces 50 megawatts of power with a parabolic trough system covering 550,000 square metres.
Protermosolar, the association that represents Spain’s solar energy sector, says that within a year another 600 megawatts will have come on-stream and that by 2013 solar capacity will have reached 2,500 megawatts..
Spain is also one of the world’s leading producers of wind power, with windfarms producing around 20,000 megawatts of electricity, and the third largest producer of hydro-electricity, after China and the US.
Physicists at Boston College have developed a nano-scale solar cell, inspired by the coaxial cable, which offers greater efficiency than any previously designed nanotech thin film solar cell
A limiting factor in making highly efficient thin film sollar cells is the need for the cells to be thick enough to collect a sufficient amount of light, yet thin enough to extract current. The Boston College researchers have found a way to resolve this challenge using a coaxial design for cells constructed with amorphous, rather than crystalline, silicon
The researchers say that the nanocoax cells yield power conversion efficiency in excess of 8 percent, which is higher than any nanostructured thin film solar cell to date.
"Many groups around the world are working on nanowire-type solar cells, most using crystalline semiconductors," said Michael Naughton, a professor of physics at Boston College. "This nanocoax cell architecture, on the other hand, does not require crystalline materials, and therefore offers promise for lower-cost solar power with ultrathin absorbers. With continued optimization, efficiencies beyond anything achieved in conventional planar architectures may be possible, while using smaller quantities of less costly material."
A team led by Professor Benoît Marsan at the Université du Québec à Montréal say that they have solved some of the problems have been hampering the development of efficient and affordable solar cells.
One of the most promising solar cells designs is the dye-sensitized cell, which was designed in the early ’90s based on the principle of photosynthesis. A dye-sensitized solar cell consists of a porous layer of nanoparticles of a white pigment (titanium dioxide) covered with a molecular dye that absorbs sunlight. The pigment-coated titanium dioxide is immersed in an electrolyte solution with a platinum-based catalyst. Sunlight passes through the platinum-based cathode and the electrolyte, and then withdraws electrons from the titanium dioxide anode.
This type of cell has some problems that have prevented its large-scale commercialisation:
Professor Marsan realized that two of the technologies developed for the electrochemical solar cell could also be applied to the dye-sensitized solar cell. Entirely new molecules, created in the laboratory, can be used in a liquid or gel electrolyte which is transparent and non-corrosive - thus improving the cell’s output and stability - and platinum can be replaced by cobalt sulphide, which is far less expensive, more efficient, more stable and more readily available.
Chih-hung Chang, an associate professor of chemical engineering at Oregon State University, is developing a new approach to solar energy which he believes may dramatically lower their cost while reducing waste and environmental impacts.
Currently, thin-film solar cells are made using methods such as sputtering, evaporation and electrodeposition. Those processes can be time-consuming, or require expensive vacuum systems or exotic chemicals that raise production costs.
An alternative approch is to use chemical bath deposition. This is a low-cost deposition technique that was developed more than a century ago. The problem is that changes in the growth solution over time make it difficult to control thickness. The depletion of reactants also limits the achievable thickness.
The technology developed at Oregon State University to deposit "nanostructure films" on various surfaces in a continuous flow microreactor makes the use of this process more commercially practical.
"We’ve now demonstrated that this system can produce thin-film solar absorbers on a glass substrate in a short time, and that’s quite significant," said Chih-hung Chang. "That’s the first time this has been done with this new technique."
Thin-film solar cells produced by applications such as this could ultimately be used in the creation of solar energy roofing systems. "If we could produce roofing products that cost-effectively produced solar energy at the same time, that would be a game changer," Chang said. "Thin film solar cells are one way that might work. All solar applications are ultimately a function of efficiency, cost and environmental safety, and these products might offer all of that."
Researchers at the Centre de Recherche Paul Pascal in Bordeaux have developed a biofuel cell which converts the chemical energy generated by photosynthesis into electrical energy.
Photosynthesis transforms carbon dioxide and water into glucose and oxygen through a complex series of chemical reactions in the presence of visible light. The researchers have developed a biofuel cell made up of two enzyme-modified electrodes that uses the products of photosynthesis (glucose and oxygen) to produce electricity.
When the cell was inserted in a living plant, in this case a cactus. the scientists observed an increase in electrical current when a desk lamp shining on the cactus was switched on, and a reduction when it was switched off. The scientists were also able to make the first ever observation of the real-time course of glucose levels during photosynthesis.
The researchers showed that a biofuel cell inserted in a cactus leaf could generate power of 9 μW per cm2. Because this yield is proportional to light intensity, stronger illumination accelerates the production of glucose and oxygen, so more fuel is available to operate the cell.
In the future, this system could form the basis for a new, environmentally-friendly and renewable way to transform solar energy into electrical energy
Researchers at the California Institute of Technology in Pasadena have reported in Nature Materials journal that they have devised a way to make flexible solar cells with silicon wires that use just 1 percent of the material needed to make conventional solar cells.
The new material uses conventional silicon configured into micron-sized wires instead of brittle wafers and encases them in a flexible polymer that can be rolled or bent. The eventual hope is to make thin, light solar cells that could be incorporated into materials such as clothing but the immediate benefit is cheaper and easier-to-install solar panels.
The researchers claim that the material would be about 15 to 20 percent efficient - about the same as solar cells currently used in rooftop panels.
These efficiencies are achieved because the wires absorb sunlight over a broader range of wavelengths and incidence angles than conventional solar panels, despite occupying only a fraction of the panel’s volume.
Researchers at Wake Forest University’s Center for Nanotechnology and Molecular Materials have made a more efficient fibre-based solar cell by coating the solar cell’s fibres with the pokeberry dye. The researchers claim that the fibre-based solar cells generate twice as much power as current thin-film technology.
Fibre-based solar cells are constructed from millions of tiny plastic fibres that can collect sunlight at oblique angles; even when the sun is low in the sky.
Whereas a traditional flat cell loses energy when the sun’s rays deflect from its shiny surface, the fibre-based design creates more surface area and confines the sun’s rays to yield twice as many kilowatt hours per day as standard flat cells. The plastic fibres for the solar cells are assembled onto plastic sheets, using a technology similar to that of creating the tops of soft-drink cups and a polymer or dye absorber is then sprayed on.
The researchers have now found that pokeberry dye is an effective absorber. The advantage of this is that pokeberry is a common weed endemic to North and South America, east Asia and New Zealand - and, so, is very cheap. The berries yield a red dye which was used as an ink by soldiers during the American Civil War.
Scientists at the University of East Anglia, led by Professor Thomas Nann, have reported a breakthrough in the production of hydrogen from water using the energy of sunlight.
Hydrogen is obtained from water by electrolysis. But, because the efficiency of the process is typically only between 20 and 40%, using a solar photovoltaic process to generate the necessary electricity uses more energy than is stored in the hydrogen which is produced.
The East Anglia team have found a way to increase the efficiency of the process to 60% or more, which could make it cost-effective.
They achieved this by using gold electrodes coated with nanoclusters of indium phosphide, which are up to 400 times more likely to absorb incoming photons than current electrodes. The nanoparticle-coated electrodes are also much more durable than alternatives.
The scientists are now investigating the possibility of using alternative, cheaper materials than gold for the electrodes.
Alcoa, the giant aluminum company, is testing a new technology, based on aircraft wing design, that it believes will lower the cost of solar energy.
Currently, the mirrored troughs used to concentrate sunlight in solar thermal power plants, use glass mirrors that are formed in the shape of a parabola and then attached to a support structure made of aluminum or steel. Alcoa is replacing the glass in the parabolic troughs with reflective aluminum and integrating this mirror into the supporting framework as a single structure.
“If you go out and look behind large parabolic troughs, you’ll find an elaborate truss structure,” said Rick Winter, a technology executive with Alcoa. “From our understanding of aerospace structures, we said if we can modify the wing box design used in aircraft and integrate a parabolic reflector, it would give us a light and stiff structure that would fundamentally affect the cost equation.”
Alcoa estimates that their design, which is currently being tested at the National Renewable Energy Laboratory in Colorado, will cut the cost of a solar thermal field by 20 percent.
A different approach to lowering the cost of mirrored troughs is being taken by SkyFuel Inc.
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