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Bigger, Cheaper Solar Cells

Phenombecile800 writes "First Solar, a start-up from Arizona, is making photovoltaic cells at a fraction of the usual cost. Their secret: increasing the light-catching area 'from postage-stamp to traffic-sign dimensions,' reducing the manufacturing time to 1/10th of the competition's, and thinning the active element to 1/100th the usual thickness over a glass substrate, which enables the production of large panels. IEEE Spectrum provides some technical details about the production process. 'Glass is placed on rollers and fed into the first chamber, where it is heated to 600 C. Then it is transferred into the second chamber, which is full of cadmium sulfide vapor, formed by heating solid CdS to 700 C. The vapor forms a submicrometer deposit on the glass as it moves through this cloud, after which a similar process in a third chamber adds a layer of micrometers-thick CdTe in about 40 seconds. Then a gust of nitrogen gas rapidly cools the panels to 300 C in a fourth chamber, strengthening the material so that it can withstand hail and high winds.'"

9 of 370 comments (clear)

  1. The old green question by gilgongo · · Score: 5, Interesting

    It's probably unanswerable, but I wonder how much energy it takes to make these cells, and how long it takes for them to offset that?

    --
    "And the meaning of words; when they cease to function; when will it start worrying you?"
    1. Re:The old green question by Anonymous Coward · · Score: 5, Interesting

      It's probably unanswerable, but I wonder how much energy it takes to make these cells, and how long it takes for them to offset that?

      We can answer anyway without even RTFA. The summary says that the cells are made out of glass (not hewn out of a crystalline ingot of silicon). Assuming 10% efficiency and 20% availability of sunlight (due to weather and geometry), you get approx 20W/m^2, or 1 kWh every two days.

      Given that glass beer bottles cost a few cents each, a square meter of glass probably takes no more than a few dozen kWh of energy to produce. Even if the vapor deposition doubles or triples that, you still would end up with an energy surplus after just a couple of months of operation.

    2. Re:The old green question by Animats · · Score: 5, Informative

      The head of Applied Materials solar division said in a talk at Stanford last year that their solar panels took two years of their own output in energy to make. They hope to get the energy breakeven point down to six months. He said the sputtering process they use in coating is energy-inefficient, and they're trying to develop something better.

      Total installed energy cost is probably higher. Home solar installations are about 50% installation cost. The big open-field installations are cheaper; they have economies of scale.

      Forbes mentions that Mojave Desert real estate is becoming more valuable because many companies want to build solar facilities there. There's plenty of space in California, Nevada, and Arizona for solar panels.

      Mike Splinter of Applied Materials (the largest maker of semiconductor fab gear) likes to say "Everybody else's costs (in the energy business) are going up, and ours are going down. We're nowhere near market saturation. This is a great business for us."

    3. Re:The old green question by djarum72 · · Score: 5, Informative

      Article gives the size of the glass, and some temps, so it may just be answerable. Googling for: how much energy does it take to manufacture glass, 5 hit (no direct link since its a f***in word doc)

      The Recipe For 1 Ton Of Glass (Resources)
                            1300 Pounds Sand

                                400 Pound Soda Ash

                                400 Pounds Limestone

                                150 Pounds Feldspar

                        24000 Gallons Water

                            4400 KWH of Energy

      So, 4400 KWH per ton.

      How much do the panels weigh?

      (.6 m) * (1.1 m) * (.5 cm) * (2 500 (kg / (m^3))) = 8.25 kilograms

      (8.25 kilograms) * 4 400 (KWh / ton) = 144 Mj

      Apart from making the glass, there is heating the glass, heating the cadmium sulfur and telluride, mining all those chemicals, etc.

      Glass specific heat is .84 J/g K.

      (.84 (J / g)) * 8.25 kg * 580 = 4 019 400 joules

      So I've calculated 148Mj for the glass manufacture and heating.
      Ignoring the cadmium, sulpher, telluride chemical mining, what do you get out of it?

      (85 watts) * 25 years = 6.7 Ã-- 10^10 joules

      How much coal is that? http://www.newton.dep.anl.gov/askasci/eng99/eng99187.htm

      6.7E10 joules) / (4.11E6 (joules / pound)) = 7 400 kg

      Remember how I ignored the energy of mining those chemicals?
      How does the energy compare for mining the GRAMS it would take to deposit a film of telluride compares to the energy for mining TONS of coal.

      The answer to what you did ask, at least for the glass + heating, is pretty easy to answer:
      (148E6 / 85) * s = 480 hours. Less than a month.

    4. Re:The old green question by bcrowell · · Score: 5, Informative

      What everyone seems to be waiting for is a cost-per-watt that is low enough so that ordinary people will decide to start buying them in large quantities without government subsidization. Suppose you're having a new house built: if you could install a ten or fifteen kilowatt solar plant and inverter for ten grand, you might figure it's worth it to borrow a little more money from the bank.

      A couple of things to keep in mind here:

      1. The cost per watt is already low enough that it makes sense for a lot of people, like me, to buy photovoltaics. It depends on what latitude you live at, how much sunny weather you get, which way your roof faces, how much shade there is on your roof, what the local price of electricity is, and what you expect the local price of electricity to be over the 25-year life of a photovoltaic system.
      2. When you talk about government subsidies, you should do an apples-to-apples comparison with the alternative, which is typically electricity that comes from burning fossil fuels. Fossil fuels enjoy massive government subsidies here in the U.S. We've fought three extremely expensive wars recently in the middle east, and I don't think we would have been involved in any of those wars if there hadn't been oil there; my grandkids will be paying for my generation's deficit-funded oil wars. There's also a huge amount of environmental damage done by burning fossil fuels, and that damage affects both this generation and future generations. If people paid the real costs of that environmental damage up front, then gas would be a lot more expensive. In places like Europe that don't subsidize fossil fuels as much, gas costs about twice what it does in the U.S.
  2. their tech by opencity · · Score: 5, Informative

    Cadmium Telluride is also a direct bandgap semiconductor which yields more watts per kg than the indirect bandgap semiconductor materials. Solar cells become less efficient at converting solar energy into electricity as their temperatures increase but Cadmium Telluride is less susceptible to cell temperature increases than traditional semiconductors generating relatively more electricity under high ambient temperatures. It's also more efficent at converting low and diffuse light to electricity more efficiently than conventional cells under cloudy weather and dawn and dusk conditions.

    They also have a recycling plan in place for the lifetime of the product - somewhat at odds with the traditional landfill methods of yore. But, no retail. They don't sell to individuals and only deal with utility companies. Finance trivia: Their stock has grown spectacularly since the IPO and there is a large investment from the Walton family (insert TV joke here)

    --
    Physics is like sex: sure, it may give some practical results, but that's not why we do it.
  3. Re:Article in two sentances: by D.+Taylor · · Score: 5, Informative

    Maybe you should have spent two hours reading the article - you might summarize it correctly then.

    The article states that current silicon photocells sell for around $3-$4 per watt.

    The new CdS/CdTe cells cost $1.14/W to produce and sell for $2.45/W.

    To reach "grid parity" they need to reduce the manufacturing costs to $0.60-$0.75/W and increase efficiency from "over 10 percent" to over 12 percent. The maximum theoretical efficiency for CdTe cells is over 20% and cells with an efficiency of 16.5% have already been made.

  4. Re:The old black question by Anonymous Coward · · Score: 5, Funny

    I think you may be seriously underestimating the deliciousness of nachos.

    Albeit not from the 7-11.

  5. Re:Obama's "Manhattan Project" On Alternative Ener by curmudgeon99 · · Score: 5, Insightful

    The reason none of these things have gone on line is because of the attitudes of people like you. There has been no concerted investment, ala the Manhattan Project. In lieu of any concentrated, directed effort to achieve a goal, nothing gets accomplished.

    The sun shines reliably for a large fraction of the day--why not invest in that?

    I find it curious how your standards of acceptability change: in the case of the alternatives available: switch grass, solar, wind, you play the pessimist. In the case of oil available off the coasts, suddenly you're an optimist. The US Department of Energy [you know, the one with all the Bush appointees in it] has said that 1.) offshore oil will not enter the supply chain for ten years minimum, not "a couple years" [implying 2], as you allege.

    Next you toss out the red-herring [meaning irrelevant] point of the Chinese drilling in Cuba--a claim which has been shown to be false so clearly that former GOP Candidate Rudy Guilliani himself uses future tense to describe this alleged problem, which is still a red herring. Do two wrongs make a right? [China allegedly drilling around Cuba and the US drilling off Florida?]

    Again, when you address the oil industry, it's all solid to you. When it comes to alternatives, it's "pie-in-the-sky". What are you, an oil-industry flack? You reluctant to learn new things or something?

    Though Nuclear does have the benefit of no greenhouse gases, it still has the same fundamental problem that oil does: it's business model is predicated on NOT dealing with its wastes! We STILL doe not have a solution to the incredibly toxic wastes we've been generating for decades. The only solution is to hide the waste. You think this is a viable alternative? Or, are you a Nuclear Energy devotee who has some business interest in that industry. When you advocate dirty technologies, how can we take you seriously?

    By the way, I lived in Houston and there is mass transit which I used while working for HP

    . And the solution is not--duh--biking 30 miles, it's moving closer to your work and downsizing your stuff.

    As I can re-iterate: I have lived all over the United States and this model in NYC is the only one I see as being viable. I've lived and commuted in Omaha, Phoenix, Houston, Cincinnati and Salt Lake City. I always chose to live as close as possible to work.

    Such name calling as labeling environmentalism "psychobabble" is convincing fewer and fewer people, my friend. The babble is coming from you fools who seem to prefer fouling your own nests.