Clean Power U Mich researchers make low cost silicon for low cost solar cells

Published on January 25th, 2013 | by Tina Casey


New “Rock Candy” Silicon Could Make Ultra-Cheap Solar Power Even Cheaper

January 25th, 2013 by  

Researchers at the University of Michigan have come up with a low-cost way to manufacture high-grade silicon, based on a concept familiar to anyone who has tried to make rock candy at home. If the breakthrough can be translated into a commercially viable process, it would make ultra-cheap solar tech like V3Solar’s Spin Cell (which we were just raving about the other day) even cheaper.

Ironically, funding for the research project came from the American Chemical Society Petroleum Research Fund, but maybe they know something we don’t.

U Mich researchers make low cost silicon for low cost solar cellsCooking Up a Batch of Low-Cost Silicon

Silicon is the key component of conventional solar cells. It comes from silicon dioxide, aka sand, which is one of the cheapest and most abundant materials on Earth, but converting sand into high grade silicon is a high cost, energy intensive process with a pretty significant carbon footprint.

As described by U Mich writer Kate McAlpine, the new process works at just 180 degrees Fahrenheit, which is a far cry from the 2,000 degrees needed for conventional silicon manufacturing.

The method basically consists of covering a liquid gallium electrode (gallium is a soft whitish metal that has a melting point around room temperature) with a layer of a solution based on silicon tetrachloride (a colorless, flammable liquid).

As in conventional silicon processing, electrons from the metal convert the silicon tetrachloride into raw silicon. The new twist is that by using soft metal with a low melting point, the research team was able to get the raw silicon to form crystals without exposing the solution to additional heat.

A Ways to Go for Low Cost Silicon

The team has observed films of silicon crystals forming on the liquid gallium electrodes, but so far the individual crystals are only about 1/2000th (yes that’s 1/2000th) of a millimeter in diameter.

There is still a long way to go before the process jumps from the lab into commercial viability, and the next steps include experimenting with other metal alloys that have low melting points.

Meanwhile, other routes to low-cost silicon based solar power are at or near commercial development, and they could go even lower if the U Mich research pans out.

One approach, illustrated by the aforementioned V3Solar Spin Cell (which by the way began life as Solarphasec), is to squeeze more power out of conventional solar cells by reconfiguring the solar module.

The Spin Cell reboots the typical flat solar panel into a 3-D cone. Along similar lines, MIT researchers have come up with a solar “tower of power” that takes advantage of 3-D angles.

The 3-D concept can also be internalized, as demonstrated by a company called (what else) Solar3D.

On a completely different note, the Obama Administration is also focusing on lowering the “soft costs” of solar power, which typically account for half the cost of a completed solar installation.

The Petroleum Research Fund

Well, here’s hoping. In any case, the really interesting part of the story is the involvement of the Petroleum Research Fund, which states at the top of its home page that its mission is to support “fundamental research directly related to petroleum or fossil fuels.”

In its vision statement following that declaration, the Fund waxes a little more expansive, describing itself as dedicated to “significantly increasing the world’s energy options,” though directly after the following note appears: “Proposals will no longer be considered in solar power, which includes photovoltaics and solar cells.”

Apparently the U Mich project got in under the wire, but it shouldn’t be surprising that a grant-making organization with roots in the petroleum industry was at least once open to solar power research.

Solar power has long been used as an economical way to provide energy to remote oil fields, where grid connections would be difficult if not impossible.

Given the energy intensity of harvesting unconventional oil, most notably from Canada’s tar sands, low-cost power in any form would be a welcome development for the petroleum industry.

Image: Rock candy by stevendepolo

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

  • andres roy

    I loved reading this piece! Well written!

    Merlen Hogg

  • merlen hogg

    I loved reading this piece! Well written!

    Merlen Hogg

  • Hans

    Silicon tetrachloride does not appear in nature, so it has to be made from siliconoxide. How is the energy footprint of this process compared to the standard way to produce silicon directly? Without answering this question we are still in the dark about the benefits of the new process.

  • Wow, if this reduces the 8 cents/kW panels, then it is truly revolutionary!


    • 8c/KW would be nice 🙂 but I think we would be happy with 8c/W too.

      In this price range non-silicon material prices would start limiting further cost reductions.

    • panels are 80 to 150 cents per watt delivered (not installed) 8 cents / kW would refer to the cost of elec generated by a system. You may of course have meant that. the key is that 8 cents would eliminate the need for susidies and make solar competetive with utility provided power anywhere in the southwest.

      • Bob_Wallace

        $2/watt installed in most parts of the US would give us roughly 8 cent per kWh electricity. No subsidies included.

        Germany is installing for $2/watt.

    • Bob_Wallace

      Were did the “8 cents/kW” come from?

      Right now the cost of silicon cells is running about 35 cents per watt. Dropping the price of silicon will help, but that’s not where the expense is with solar. US solar is averaging around $3.50 watt while panels are averaging about 63 cents.

      • My mistake – I was confused by the “8 cents kWh” because that would need a period of time to be meaningful. If you buy panels for a certain cost, and you say they cost X per kWh, you also have to say how long a period of time it takes to get to that number.


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