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"  (Photograph by Tim Robberts/Getty Images) A long-sought solar milestone was eclipsed on Tuesday, when Tempe, Ariz.-based First Solar Inc. announced that the manufacturing costs for its thin-film photovoltaic panels had dipped below $1 per watt for the first time. With comparable costs for standard silicon panels still hovering in the $3 range, it&amp;#039;s tempting to conclude that First Solar&amp;#039;s cadmium telluride (CdTe) technology has won the race. But if we&amp;#039;re concerned about the big picture (scaling up solar until it&amp;#039;s a cheap and ubiquitous antidote to global warming and foreign oil) a forthcoming study from the University of California-Berkeley and Lawrence Berkeley National Laboratory suggests that neither material has what it takes compared to lesser-known alternatives such as\u2014we&amp;#039;re not kidding\u2014fool&amp;#039;s gold. Even if the solar cell market were to grow at 56 percent a year for the next 10 years\u2014slightly higher than the rapid growth of the past year\u2014photovoltaics would still only account for about 2.5 percent of global electricity, LBNL researcher Cyrus Wadia says. &amp;quot;First Solar is great, as long as we&amp;#039;re talking megawatts or gigawatts,&amp;quot; he says. &amp;quot;But as soon as they have to start rolling out terawatts, that&amp;#039;s where I believe they will reach some limitations.&amp;quot;  Even the current rate of growth won&amp;#039;t be easy to sustain. Despite the buck-per-watt announcement, First Solar&amp;#039;s share price plummeted more than 20 percent on Wednesday, thanks to warnings from CEO Mike Ahearn about the effect of the credit crisis on potential solar customers\u2014as much as 10 to 15 percent of current orders might default. He recently told analysts in a conference call that &amp;quot;as good as things look for the mid-term and beyond, the short-term outlook for the solar industry in our view has never looked more difficult.&amp;quot; (A transcript is available at SeekingAlpha.)  First Solar&amp;#039;s eventual goal is &amp;quot;grid parity,&amp;quot; a phrase that refers to making solar power cost the same as competing conventional power sources without subsidies. Right now the cost of making panels accounts for a little less than half the total cost of installation. The company estimates that it needs to get manufacturing costs down to $0.65 to $0.70 per watt, and other installation costs down to $1 a watt in order to reach grid parity\u2014goals First Solar plans to reach by 2012. The question, though, is whether First Solar or any other solar manufacturer would be able to handle the flood of orders that would ensue if they reached competitive cost. At that point, it comes down to a matter of having enough of raw materials. That is where the real limitations come to bear, according to a paper that will appear in the March issue of the journal Environmental Science &amp;amp;amp; Technology. In the paper, Wadia and colleagues Paul Alivisatos and Daniel Kammen evaluated the global supplies and extraction costs for 23 promising photovoltaic semiconductor materials and found that the three materials that currently dominate the market\u2014silicon, CdTe and another thin-film technology based on copper indium gallium selenide (CIGS)\u2014all have limitations when ordered in mass. While silicon is the second-most abundant element in the Earth&amp;#039;s crust, it requires enormous amounts of energy to convert into a usable crystalline form. This is a fundamental thermodynamic barrier that will keep silicon costs comparatively high. Both CIGS and First Solar&amp;#039;s CdTe rank poorly in abundance and extraction cost, with CdTe ranking dead last in long-term potential based on current annual extraction rates. That doesn&amp;#039;t mean these materials won&amp;#039;t play a significant role, Wadia says. &amp;quot;It&amp;#039;s great to see the success the thin-film and silicon companies have had in pushing the limits of how fast and how cheap they can make panels.&amp;quot; But it may also pay to devote some federal R&amp;amp;amp;D funds to research on alternative materials that are abundant, nontoxic and cheap. To that end, Wadia and his colleagues found that iron pyrite\u2014better known as fool&amp;#039;s gold\u2014was several orders of magnitude better than any of the alternatives, based on both cost and abundance. Copper sulfide and copper oxide were also attractive candidates. The problem with these materials is that they&amp;#039;re less efficient in converting the sun&amp;#039;s rays to electricity, and as a result have been the focus of considerably less research. But the Berkeley study accounts for this fact, and concludes that lower-efficiency materials that are cheaper and more abundant will ultimately serve the alternative energy market better. Kammen, who is the founding director of Berkeley&amp;#039;s Renewable and Appropriate Energy Laboratory and advised the Obama campaign on energy issues, still considers the First Solar dollar-a-watt announcement to be an exciting development. &amp;quot;It shows that the rapid and important expansion of the solar industry needs the sustained research and manufacturing expertise of globally leading companies like First Solar,&amp;quot; he says. &amp;quot;It also sets a new and critical bar for all companies to work to achieve.&amp;quot; That good news wasn&amp;#039;t enough to save First Solar&amp;#039;s share price on Wednesday. But the message of the Berkeley study is that unlike the stock market, we need to think long-term, and plan for the solar power we want to see a decade or more in the future. And that means doing some painstaking basic research on neglected materials that, for now, cost a lot more than a dollar a watt. "^^<http://www.w3.org/2001/XMLSchema#string>
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