Micron-sized solar cells beat wafer-sized cells

EETimes ^ | 12/23/09 | R. Colin Johnson

[PeaceBeWithYou]

Sandia National Labs recasts solar industry with MEMS

PORTLAND, Ore. — Sandia National Labs has harnessed silicon's natural tendency to grow into islands and used micro-electro-mechanical systems techniques to free those islands into the world's smallest solar cells.

Sandia claims the micron-sized solar cells are as efficient as their wafer-sized big brothers, but consume only one hundredth the amount of semiconductor.

Rather than force solar cells to grow across an entire wafer in a perfect crystalline lattice, and throw the whole wafer away if any imperfections develop, Sandia National Labs has found that smaller is better.

Measuring just 100 microns round and just 14-to-20 microns thick—including electrodes—the tiny solar cells resemble snowflakes, but can be ganged together in parallel to provide whatever current generation capacity required by an application.

In addition, they can also be wired in series to generate high voltages that are impossible with conventional solar cells. In the space required for 12 volts from a traditional solar cell, hundreds of volts can be generated by micron-sized solar cells wired in series.

Sandia also claims their solar cells small size would allow them to be affixed to flexible surfaces, even clothing, turning almost any surface into a solar panel.

In tests, Sandia demonstrated that a conventional pick-and-place robot can assemble about 130,000 of the tiny solar cells per hour over several square meters at a cost of approximately one-tenth of a cent per cell.

Funding was provided by the Department of Energy's Solar Energy Technology Program and Sandia National Laboratory's Directed Research & Development program.

[cripplecreek]

The special lab produced solar cells are struggling to get to 40% effiency.

I'm talking about something I saw on the discovery channel a while back. They managed to achieve 80% efficiency but were having to manually align the crystals under a microscope. We're talking about several thousand dollars per square inch.

[PapaBear3625]

I’ve been reading about these innovations for 30 years. When does the application arrive that is cost effective without the government subsidy?

They're already here, depending on the application.

Solar powered calculators have been around for decades. Solar powered emergency phones along the highways have been around for a number of years. Using solar power to charge batteries for evening lights for driveway paths have been around for a few years and they're getting better.

With each new increment in efficiency and decrement in price, solar becomes cost effective in more and more applications. Solar powered homes in the North will be the last.

[Balding_Eagle]

When do we see this technology make sense economically?

It is far easier, and quicker, than you can imagine.

The first step is to regulate your use of the wood stoves, essentially making it a crime for you to heat your home with the ordinary. Then, punish coal companies and stop the construction of coal fired power plants.

There, project complete, it now makes sense to use this technology if you want to live in a warm home.

[MSF BU]

There is a degree of truth to what you say. Fortunately I have decent neighbors (as of now) who could care less that I can burn. My 10+ acres of hardwood may turn out to be an asset after all.

[PeaceBeWithYou]

There is also full spectrum solar cells which produce in the 70% range using Indium Gallium Nitride. Production cost should be near that of current InGaN.

If the process described in this article could be applied to the InGaN full spectrum cells, cost would be small, efficiency would be high, and mass production would be a breeze.

[dangerdoc]

I’d like to see that show, usual suspects (wiki etc.) are still showing the record holder in the low 40’s.