Physorg.com reports that researchers at Georgia Tech Research Institute have found a 3-D way to design solar cells. The design uses tiny "tower" structures like high-rise buildings in a city. The new cells trap light between their tower structures.

Jud Ready, a senior research engineer on the team, said, "Our goal is to harvest every last photon that is available to our cells. By capturing more of the light in our 3-D structures, we can use much smaller photovoltaic arrays. On a satellite or other spacecraft, that would mean less weight and less space taken up with the PV system."

The tiny towers are 100 microns tall and 40 microns by 40 microns square. They stand just 10 microns apart, and contain millions of carbon nanotubes. Flat polysilicon-based solar cells reflect much of the light that strikes them.

Unlike flat cells, the new towers absorb light received from many different angles. This means they are efficient even when the sun is not directly overhead. This gives them the advantages of active solar systems that track the sun, but at the expense of energy use.

They could be used on spacecraft, reducing weight and complexity and improving reliability. These are all vital considerations where each pound is worth millions of dollars.

Further, because the 3-D cells absorb more of the photons than conventional cells, their coatings can be made thinner. This means the electrons can move to power lines more quickly, which cuts the reabsorption of electrons -- a problem with conventional solar cells.

Not surprisingly, nanotechnology is involved. A special process grows the towers at the molecular level on an iron substrate. They are then coated with cadmium telluride and cadmium sulfide to create photovoltaic layers. A thin coating of conducting material is added to complete them.

Cadmium was chosen because it seemed a suitable material. However, many other materials can be used and will be tested to optimize efficiency. Likewise, height and spacing for the towers needs to be optimized.

NewCyte, an Ohio company, is developing designs for using the towers in Earth-based solar collector panels.
There is a gap of at least several years from successful prototype of a new design to manufacture and commercialization. When that happens, the design must be incorporated into a system that’s user-friendly, reliable, easy to install and easy to maintain.

Should this new technology fulfill its promise, it will need a vendor such as Akeena to take it to market. While another company could wind up with the technology, Akeena is rapidly emerging as one of a handful of leaders in America’s solar industry.

Akeena (AKNS) has the most customer-centered philosophy of any of the serious players. That gives it a good chance of access to this technology, when these micro-towers are ready for market.
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