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More-Powerful Solar Cells

Continued from page 1

By Kevin Bullis

Thursday, March 27, 2008

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Groovy solar: Facets etched into the surface of wires redirect incoming light so that it is absorbed by a solar cell rather than reflected away. The wires serve to collect current generated by a solar cell.
Credit: 1366 Technologies

The second innovation involves the silver wires that harvest electrical current generated by the silicon. Sachs has developed a method for making these wires as small as one-fifth the width of the wires that are typically used, while improving their conductivity. The thinner wires use less silver, which cuts down costs. Also, because the wires are thinner, they can be spaced closer together and still block less light than ordinary wires can. The closer spacing makes the wires more efficient at collecting electrical current generated in the silicon.

The final improvement has to do with a set of wide, flat wires used to collect current from the thin silver wires. These bars typically block light entering the cell, reducing efficiency. But Sachs has etched their surfaces so that they act as faceted mirrors. This achieves an effect similar to the texturing of the silicon surface. While the improvements add costs in some ways, the increases are offset by savings elsewhere, such as from using less silver, Sachs says.

While 1366 Technologies plans to manufacture its own cells, Sachs says that it is also open to licensing the technology to other solar-cell makers. Ultimately, Sachs hopes that his technology will speed the adoption of solar power to meet global energy requirements. "We need an exponential growth curve now," he says. "Not 15 years from now--that's too late."

Comments

  • RTTedrow
    The difference between a projected $1.30/watt for these solar cells and $1.00/watt for coal would be more than overcome if coal-fired utilities and other, similar polluters were required to use effective air scrubbers and other clean coal technologies. A cost of $1.00 per watt for the giant central, southern and western coal burning utilities/polluters does not in any way reflect the true cost of their operations to the US population.
    Rate this comment: 12345

    rttedrow
    03/27/2008
    Posts:43
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    4/5
    • Re: RTTedrow
      Dr. Sachs mentioned that factors, such as a price on carbon dioxide emissions, could make it easier for solar to compete. Of course, solar may also have hidden costs. Refining silicon, for example, can produce toxic materials.
      Rate this comment: 12345

      Kevin Bullis
      03/27/2008
      Posts:92
      Avg Rating:
      4/5
  • When can I buy one?
    I am tired of stories about some new solar cell just around the corner, I want a product now.  I am sick of paying edison rip off prices for power and gas. When will I be able to buy one these super cheap solar cells for my home?
    Rate this comment: 12345

    jmaximus9
    03/27/2008
    Posts:83
    Avg Rating:
    3/5
  • Increase the efficiency even more
    It is possible to increase efficiency even more with various relatively well developed technologies, such as up-conversion and down-conversion layers/coatings.

    Even easier: placing a mirror behind the panels to boost performance a bit, if the configuration allows it of course (eg a flat roof would work fine).

    But the limits of conventional flat plate silicon based solar cells are in sight. They use a lot of material and the manufacturing plants are capital intensive. Roll-to-roll manufacturing of thin films carries far lower capital costs, so more production capacity can come on-line with similar investments. Then, more money can be earned quicker, so that even more production capacity can be brought on-line. You can see where this is going; factories with low capital costs can scale quicker, and do a lot more with less materials.

    A major breakthrough would be to combine these advantages with the high efficiency advantage of flat plates. Up and down conversion could help, but what's really needed is exploiting nano-effects and possibly different materials.

    Amorphous diamond, for example, could replace silicon as a semiconductor, allowing over 50% conversion efficiency while being more stable to cosmic rays than amorphous silicon thinfilms but with a similar potential for cheap roll-to-roll mass manufacturing.

    High efficiency is important, as it can (ceteris paribus) reduce the installation costs, structural support costs, maintenance costs etc. which are significant when all combined.

    Unless the initial cost targets can be brought to market really fast, they may find it too high a cost target compared with various competing technologies. We may have to be a bit more ambitious.
    Rate this comment: 12345

    Siphon
    03/28/2008
    Posts:144
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    3/5
  • life-span and lossed light
    Personally i think the issue is about life-span of the technology rather than its efficiency which is pointless if it doesnt last.

    I might have misunderstood the science but this is mine to date.
    Lets say 100 photons pass through a film that has a transfer effiency of 4%, this to me means 4% of the lights energy from e=mc2 equation is turned to useable energy. This tells me that an enormous amount of light is needed to make a little energy.

    So isnt it better to have something with 1% efficiency that lasts "forever" and can be layered to take 100% of the energy over time?

    Eg a parabolic shape focuses light to an area, and mirrors can be layered such that no light emerges, and harnessed with gravity, aka blackholes that let no light out the light say could be made to have a 100% efficiency transfer from a 1% absorbing/tranfering material.

    I say forget efficiency and collect all the light let it bounce around indeffinately being collected. Light can pass through itself so eventually you would have masses of light bouncing around indeffinately being transfered at such a huge rate it would be amazing.

    Thats my 2 and half twisted cents.

    Motto is dont lose the light.
    Rate this comment: 12345

    mattgroom
    05/08/2008
    Posts:1
    Avg Rating:
    2/5
  • Energy Providers Block Home Power Generation
    At least in my state, the power company puts up paperwork and policy barriers that make it prohibitively difficult to feed power into the grid with any compensation, which is a major component of shortening the payback period to a reasonable time.  Keeping power generation centralized apparently makes them feel more secure and in control of their profitability, and, until state legislators take action, the situation will continue to discourage home-based electricity generation.  I write my representatives often, and encourage you to as well.
    Rate this comment: 12345

    timprosser
    05/23/2008
    Posts:1
    Avg Rating:
    4/5

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