DYE Solar cells: a cheaper solution?

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Solar Cells for Cheap

Not everyone gets a solar cell named after them: but Michael Gratzel did. He says his novel technology, which promises electricity-generating windows and low manufacturing costs, is ready for the market.

 

By Kevin Bullis

 

Michael Grätzel, chemistry professor at the Ecoles Polytechniques Fédérales de Lausanne in Switzerland, is most famous for inventing a new type of solar cell that could cost much less than conventional photovoltaics. Now, 15 years after the first prototypes, what he calls the dye-sensitized cell (and everyone else calls the Grätzel cell) is in limited production by Konarka, a company based in Lowell, MA, and will soon be more widely available.

 

Grätzel is now working on taking advantage of the ability of nanocrystals to dramatically increase the efficiency of solar cells.

 

Technology Review asked him about the challenges to making cheap solar cells, and why new technologies like his, which take much less energy to manufacture than conventional solar cells, are so important.

 

Technology Review: Why has it been so difficult to make efficient, yet inexpensive solar cells that could compete with fossil fuels as sources of electricity?

 

 

Michael Grätzel: It's perhaps just the way things evolved. Silicon cells were first made for [outer] space, and there was a lot of money available so the technology that was first developed was an expensive technology. The cell we have been developing on the other hand is closer to photosynthesis.

 

TR: What is its similarity to photosynthesis?

 

MG: That has to do with the absorption of light. Light generates electrons and positive carriers and they have to be transported. In a semiconductor silicon cell, silicon material absorbs light, but it also conducts the negative and positive charge carriers. An electric field has to be there to separate those charges. All of this has to be done by one material--silicon has to perform at least three functions. To do that, you need very pure materials, and that brings the price up.

 

On the other hand, the dye cell uses a molecule to absorb light. It's like chlorophyll in photosynthesis, a molecule that absorbs light. But the chlorophyll's not involved in charge transport. It just absorbs light and generates a charge, and then those charges are conducted by some well-established mechanisms. That's exactly what our system does.

 

The real breakthrough came with the nanoscopic particles. You have hundreds of particles stacked on top of each other in our light harvesting system.

 

TR: So we have a stack of nanosized particles...

 

MG: ...covered with dye.

 

TR: The dye absorbs the light, and the electron is transferred to the nanoparticles?

 

MG: Yes.

 

TR: The image of solar cells is changing. They used to be ugly boxes added to roofs as an afterthought. But now we are starting to see more attractive packaging, and even solar shingles (see "Beyond the Solar Panel"). Will dye-sensitized cells contribute to this evolution?

 

 

.. more: http://www.technologyreview.com/read_artic...0&ch=energy

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The cells are now in limited production by Konarka, based in Lowell, MA USA, primarily for the military. Konarka has just announced a 25-megawatt facility for a foil-backed, dye-sensitized solar cells, by G24innovations ltd. in England, based on a Konarka license.

 

Konarka, based in Lowell, MA USA: http://www.konarka.com/

 

Konarka develops light-activated power plastic that is flexible, lightweight, lower in cost and much more versatile in application than traditional silicon-based solar cells.

Materials Make It Possible

 

These new materials are made from conducting polymers and nano-engineered materials that can be coated or printed onto a surface in a process similar to how photographic film is made.

World Without Wires™

 

Anywhere there is light and a battery, power plastic makes it possible for devices, systems and structures to have their own low-cost embedded sources of renewable power. By combining energy generation and power consumption within the same device, Konarka enables manufacturers to create a World Without Wires™ with truly wireless applications.

[HollandPark]

Uni-Solar, part of ECD-Ovionics, already has something similar

 

purchase the above from : uk price list

 

The above flexible solar cells are based on a sophisticated multi-layer amorphous silicon thin-film solar cell developed originally by Energy Conversion Devices, Inc, USA. This spectrum-splitting cell, shown schematically below, is constructed of separate p-i-n type, amorphous semiconductor solar sub-cells, each with a different spectral response characteristic. This allows the cell to convert the different visible and near infrared wavelengths of sunlight with optimal efficiency. This spectrum-splitting multijunction design now holds all the world's records for amorphous silicon solar cell efficiency, including the highest stable efficiency measured by the National Renewable Energy Laboratory (NREL) for a small-area amorphous silicon solar cell @ 13 percent

 

 

DEVELOPMENT HISTORY:

 

Using their own thin-film, vapor-deposited amorphous silicon (a-Si) alloy materials, Uni-Solar have developed proprietary technology to reduce the materials cost in a solar cell. Because a-Si absorbs light more efficiently than its crystalline counterpart, the a-Si solar cell thickness can be 100 times less, thereby significantly reducing materials cost. By utilizing a flexible, stainless steel substrate and polymer-based encapsulates, PV products utilizing our technology can be very lightweight, flexible and durable. No broken parts during shipping and easy to transport to remote rural areas, thus saving shipping costs, and can be installed without breakage.

 

Amorphous cells with different light absorption properties deposited continuously, one on top of another, to capture the broad solar spectrum more effectively. This increases the energy conversion efficiency of the multi-cell device and improves performance stability. The multi-junction approach has resulted in world record efficiencies for these cells. Each of the nine thin-film semiconductor layers that comprise the cell is sequentially deposited in separate, dynamically-isolated, plasma enhanced chemical vapor deposition (PECVD) chambers as the stainless steel substrate progresses through the machine.

 

To further reduce the manufacturing cost of PV modules, they have pioneered the development of and have the fundamental patents on a unique approach utilizing proprietary continuous roll-to-roll solar cell deposition process. Using a roll of flexible stainless steel that is a half-mile long and 14 inches wide, nine thin-film layers of a-Si alloy are deposited sequentially in a high yield, automated machine to make a continuous, three-cell stacked structure. The roll of solar cell material is processed further for use in a variety of photovoltaic products.

 

Uni-Solar have an annual production capacity of 5MW that is now being expanded to 30MW by the addition of a new facility located in Auburn Hills, MI. This plant is fully automated and allows simultaneous processing of six rolls of stainless steel, each 1 1/2 miles long, during deposition of the a-Si layers. The thin-film materials, cell designs, and manufacturing processes used by United Solar Systems Corp. are protected by more than 160 issued U.S. patents.

 

Find out more from: United Solar Systems Corp.