A solar power milestone was reached on Tuesday when First Solar Inc brought its manufacturing costs for solar panels down to $1 per watt. But a study from the University of California and Lawrence Berkeley National Labs suggests that this might be the bottom for a price-point—if solar power is ever going to scale up to become competitive with other forms of energy. Here are the new challenges facing the solar industry and some suggestions to make a brighter future.
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's tempting to conclude that First Solar's cadmium telluride (CdTe) technology has won the race. But if we're concerned about the big picture (scaling up solar until it'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—we're not kidding—fool's gold.
Even if the solar cell market were to grow at 56 percent a year for the next 10 years—slightly higher than the rapid growth of the past year—photovoltaics would still only account for about 2.5 percent of global electricity, LBNL researcher Cyrus Wadia says. "First Solar is great, as long as we're talking megawatts or gigawatts," he says. "But as soon as they have to start rolling out terawatts, that's where I believe they will reach some limitations."
Even the current rate of growth won't be easy to sustain. Despite the buck-per-watt announcement, First Solar'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—as much as 10 to 15 percent of current orders might default. He recently told analysts in a conference call that "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."
就拿目前的增长率来说,那也是不容易满足供应的。尽管有了这个声明,首日公司的股票价格在周3也下降了20%之多,下跌的原因归结为首席执行官麦克-亚西姆的警告 --- 光伏电池组的潜在客户由于信贷危机将取消10 -15的定单。他最近在一次会议采访中告诉分析家们说:“从中期及远景来看,情况还不错,但是,目前的困难也是前所未有的。”
First Solar's eventual goal is "grid parity," 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—goals First Solar plans to reach by 2012.
首日公司的最终目标是“电板等价,”该口号的意思就是要使太阳能的价格跟常规的能源相同,而不需要补贴。目前,制造电池组的价格不及合计安装费用的一半。该公司估计,他们必须把生产价格降到每瓦0.65美元到0.70美元之间,把其它安装费用降到每瓦1美元,以便实现首日公司2012年的电板等价计划目标。
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 & 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—silicon, CdTe and another thin-film technology based on copper indium gallium selenide (CIGS)—all have limitations when ordered in mass. While silicon is the second-most abundant element in the Earth'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's CdTe rank poorly in abundance and extraction cost, with CdTe ranking dead last in long-term potential based on current annual extraction rates.
然而,问题是如果他们能够在价格上具备了竞争力,首日或其它太阳能电池组生产厂家能否应对未来必将蜂拥而至的定单。那时,最终的问题就是有没有足够的原材料了,这就是真正面临的制约,这就是即将在3月份的《环境科学与技术》期刊上发表的论文所提出的观点。在这篇文章中,瓦迪亚及其同事,保罗-亚利威萨特斯和丹尼尔-卡门评估了全球23种有利用价值的光伏半导体材料的供料及提取费用,他们发现,目前主宰市场的3种材料,硅、碲化铬及另一种铜铟硒化镓薄膜,面对大量生产,均有局限性。虽然硅是世界上储量位据第二的丰富材料,但是要提炼出可用的硅晶体,却要耗费太大的能量。这个基本的热力学壁垒目前仍然使得单晶硅的价格维持在一个较高的水平。铜铟硒化镓跟首日公司的碲化铬在储量和提取费用方面的排名都不高。参照目前的年提取率,碲化铬从长远的角度来看,排在最后。
That doesn't mean these materials won't play a significant role, Wadia says. "It'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." But it may also pay to devote some federal R&D funds to research on alternative materials that are abundant, nontoxic and cheap.
瓦迪亚说,这并不意味着这些材料起不了多大作用。“看到使用薄膜和硅板的公司取得成功,令人欣慰,他们在突破极限,以很快的速度和低廉的价格制成了电池组。”但是,动用一些联邦研发基金用于寻求储量丰富、无毒、廉价的替代材料也是值得一试的。
To that end, Wadia and his colleagues found that iron pyrite—better known as fool's gold—was 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're less efficient in converting the sun'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.
为了这一目的,瓦迪亚和他的同事们发现硫化铁 --- 俗称傻瓜金,从储量及价格上优于其它任何替代材料几个数量级之多。硫化铜和氧化铜也是很抢眼的替代材料。这些材料的问题是,它们将阳光转化成电的效率相对较低,因此没有受到研究界的关注。但是,伯克理研究报告论及了这个事实,并得出结论,低效率,但廉价而储量丰富的材料最终将更好地服务于替代能源市场。
Kammen, who is the founding director of Berkeley'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. "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," he says. "It also sets a new and critical bar for all companies to work to achieve."
卡门是伯克理可再生清洁能源实验室的首任主任,也曾经给奥巴马竞选充当能源问题顾问,仍然以为首日公司的每瓦1美元的声明是个可喜的进展。他说:“这表明,太阳能工业的快速大发展离不开象首日这样的世界龙头企业持续的专门研究与生产技术。”“这也给所有企业树立了新的临界标杆。”
That good news wasn't enough to save First Solar'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.