Somenath Mitra at the New Jersey Institute of Technology claims to have developed a solar cell that could be printed very cheaply on flexible plastic sheets.

"Someday homeowners will be able to print sheets of these solar cells with inexpensive home-based inkjet printers," he said. "Consumers can then slap the finished product on a wall, roof or billboard to create their own power stations."

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Purified silicon, also used for making computer chips, is a core material for fabricating conventional solar cells. However, the processing of a material such as purified silicon is complex.

"Developing organic solar cells from polymers, however, is a cheap and potentially simpler alternative," said Mitra.

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The solar cell developed at NJIT uses carbon nanotubes 50,000 times smaller than a human hair.
Just one nanotube can conduct current better than any conventional electrical wire, and nanotubes are significantly better conductors than copper.

Mitra and his research team took the carbon nanotubes and combined them with tiny carbon buckyballs (known as fullerenes) to form snake-like structures.

Buckyballs trap electrons, although they cannot make electrons flow. Add sunlight to excite the polymers, and the buckyballs will grab the electrons. Nanotubes, behaving like copper wires, will then be able to make the electrons or current flow.

I believe that homeowners will move quickly toward any alternative energy option with a payback period of a year or less. In other words, if what they save off their electric bill in a year pays for the purchase and installation, people will do it – whether it is solar, wind, or whatever.

There's two ways to close the gap toward a one-year payback. Increased efficiency of the alternative energy power method (for example: a better solar cell that converts more sunlight to electricity), or decreased cost for manufacturing.

We're not given any indication how much power carbon nanotube solar cells could produce or the cost for their manufacture. But if the cost of manufacture is 1/10th the cost of standard solar (to pull numbers out of the air), you could be half as efficient as standard solar cells and still be five times ahead on the payback equation.

We have a lot of unutilized roof space in the world. If we had to choose, it would be smart to put emphasis on providing a cheap way to utilize the space rather than on the efficiency of solar cells that are too expensive to cover the space.

UPDATE:

Phil has more on this over at L2SI.