Innovation Puts Next-Generation

Solar Cells on the Horizon.

Could dye from berries be the answer??

ScienceDaily (Dec. 2, 2009) — In a world first, a Monash University-led international research team has developed an innovative way to boost the output of the next generation of solar cells.

Scientists at Monash University, in collaboration with colleagues from the universities of Wollongong and Ulm in Germany, have produced tandem dye-sensitised solar cells with a three-fold increase in energy conversion efficiency compared with previously reported tandem dye-sensitised solar cells.

Lead researcher Dr Udo Bach, from Monash University, said the breakthrough had the potential to increase the energy generation performance of the cells and make them a viable and competitive alternative to traditional silicon solar cells.

Dr Bach said the key was the discovery of a new, more efficient type of dye that made the operation of inverse dye-sensitised solar cells much more efficient.

When the research team combined two types of dye-sensitised solar cell — one inverse and the other classic — into a simple stack, they were able to produce for the first time a tandem solar cell that exceeded the efficiency of its individual components.

“The tandem approach — stacking many solar cells together — has been successfully used in conventional photovoltaic devices to maximise energy generation, but there have been obstacles in doing this with dye-sensitised cells because there has not been a method for creating an inverse system that would allow dye molecules to efficiently pass on positive charges to a semiconductor when illuminated with light,” Dr Bach said.

“Inverse dye-sensitised solar cells are the key to producing dye-sensitised tandem solar cells, but the challenge has been to find a way to make them perform more effectively. By creating a way of making inverse dye-sensitised solar cells operate very efficiently we have opened the way for dye-sensitised tandem solar cells to become a commercial reality.”

Although dye-sensitised solar cells have been the focus of research for a number of years because they can be fabricated with relative simplicity and cost-efficiency, their effectiveness has not been on par with high-performance silicon solar cells.

Dr Bach said the breakthrough, which is detailed in a paper published in Nature Materials, was an important milestone in the ongoing development of viable and efficient solar cell technology.

“While this new tandem technology is still in its early infancy, it represents an important first step towards the development of the next generation of solar cells that can be produced at low cost and with energy efficient production methods,” he said.

“With this innovation we are one step closer to the creation of a cost-efficient and carbon-neutral energy source.”

Sourced and published by Henry Sapiecha 8th June 2010

Solar energy technology is advancing daily. Now, a new, high-tech system is working to efficiently harness the power of the sun and drastically reduce harmful carbon dioxide emissions. Today, there are more than 76 million residential buildings and nearly 5 million commercial buildings in the United States. Combined, they use two-thirds of all electricity consumed in the United States and produce 35 percent of all carbon dioxide emissions. Anna Dyson, an architectural scientist from Rensselaer Polytechnic Institute in Troy, New York, is leading the way to make solar energy a real
alternative to pollution-emitting fossil fuels. Her system contains rows of thin lenses that track the sun’s movement.
Sunlight floods each lens and is focused onto a postage-stamp sized, high-tech solar cell. Dyson says, “Really, what wewant to do is be capturing and transferring that energy for usable means.” Conventional solar systems are about 14percent efficient. This system has a combined heat and power efficiency of nearly 80 percent. “What they’re doing is veryefficiently capturing and transferring that light into electricity and the solar heat into hot water,” Dyson explains.

“We basically have a system that can sense where the sun is at any time, and then the modules will basically be facing directly perpendicular to the incoming sun rays,” she says. The lenses will be nestled between window panes and all of the pieces will be made of glass. Michael Jensen, Ph.D., a mechanical engineer from Rensselaer Polytechnic Institute says reducing dependency on fossil fuels is critical. Dr. Jensen explains, “We use fewer fossil fuels, then we are going to put less CO2 into the atmosphere. We are going to decrease the effects on global warming.” This system will also lower the lighting needs of buildings, as it will provide usable light inside. It could supply as much as 50 percent of the energy needed for a building to operate.

The system is set to be installed in the Center for Excellence and Environmental EnergySystems in Syracuse, New York, in 2008, and in the Fashion Institute of Technology in New York City by 2009.
BACKGROUND: A team of different types of scientists at Rensselaer Polytechnic Institute has developed a radical new solar energy technology that promises to collect and distribute solar energy more efficiently. Rows, or stacks, of pivoting lenses incorporated into a glass building facade track the movement of the sun across the sky, focusing its rays onto high-tech solar cells. The new system uses high-tech solar-concentrator technology and advanced materials. The fullsize prototype will be incorporated into a new building at The Center of Excellence in Syracuse, New York.
HOW IT WORKS: The key breakthrough is the miniaturized concentrator solar cell, which uses a lens with concentric grooves to focus collected light. Even though it is only the size of a postage stamp — compared to the usual solar collector area that spans 4 x 4 feet — the cell is much more efficient in collecting and reusing solar energy. The lens focuses incoming sunlight onto the solar cell. Microchannels at the base of the module transfer energy in the form of heat and light to wires contained inside. Each vertical stack of lenses rolls and tilts like a track blind, keeping the surface of the
lenses faced to incoming sunlight as the sun changes position in the sky throughout the day. Incorporating these new cells into arrays could make solar energy an option that is competitive with other energy sources, reducing our dependency on fossil fuels.
ABOUT SOLAR CELLS: The solar cells on calculators and satellites are photovoltaic cells or modules: groups of cells electrically connected and packaged together. Photovoltaics convert sunlight directly into electricity.

Photovoltaic cells are made of semiconductor materials like silicon. When light strikes the cell, a certain portion of the light is absorbed by the semiconductor material. The energy of the absorbed light knocks electrons in the semiconductor material loose,
allowing them to flow freely. Photovoltaic cells also all have one or more electric fields that act to force the freed electrons to flow in a certain direction. This flow of electrons is a current. By placing metal contacts on the top and bottom of the photovoltaic cell, the current can be drawn off to be used. For example, the current can power a calculator. However, conventional photovoltaic panels made from silicon to provide electricity are expensive, and thus not cost-competitive with electricity from the power grid.

Sourced and published by Henry Sapiecha 3rd May 2010