光伏技术-蒸蒸日上

1、光伏技术-蒸蒸日上简介来自太阳的绿色能源取之不尽，用之不竭，人类利用太阳能的步伐正在加快。越来越多的研究成果降低了太阳能利用的成本，提高了利用的效率，不断给市场注入活力。还在研究的光伏技术更是给人类提供了无穷的想象空间。 想要更多地了解蓬勃发展的太阳能行业，本文可以提供很多有价值的信息。太阳能是首屈一指的绿色能源，太阳能光伏市场正蓬勃发展。自2002年以来，产量每两年翻一番，使其成为增长最快的能源部门。受到政府激励政策的支持，这一行业正在繁荣昌盛；相关的研究正在开辟一条条新的光明大道并使成本不断降低。提交给专利合作条约组织太阳能方面的专利申请数量从2004年的460件增加到2008年的1411

2、件，增加了两倍。光伏效应-一种把光转换成电的现象-由法国物理学家埃德蒙贝克勒尔在1839年首先提出。艾伯特爱因斯坦因1904年出版的关于这一课题的理论著作而获得了诺贝尔奖。受1950年到1969年的太空竞赛刺激，人们对此进行了深入研究，从1955年开始，许多公司开发出了太阳能电池或者叫光伏电池，并将其推向市场。第一颗太阳能动力卫星“先驱者1号”在1958年发射并运行了8年。其他太阳能动力卫星随之而来。太阳能电力继续作为辅助能源被应用在宇宙飞船上，并为轨道卫星提供动力。这一技术在应用到地面时却发展的慢一些。光伏市场投资回报与支出不相匹配：几乎来自任何其他资源的网电-煤电、水电或核电-过去是，现在

3、还是要便宜的多。但是，在过去的十年中，气候变化问题已经改变了我们的看法。二氧化碳增加导致的环境问题已经拉响了警报：现在迫切需要新的无污染技术并重新关注旧技术，在成本和大规模生产还是首要考虑因素的时候旧技术被忽视了。就这样，光伏技术从多年前储存的几乎被遗忘的专利信息堆中冒了出来。来自太阳 一小时内，太阳提供的能源可以供应地球一年所需能源还有余。 一天之内，太阳提供的能源比全球人口27年所能消耗的能源还多。 来源：bipv technology光伏市场“全球光伏市场分析和2020年展望”中最吸引眼球的一点是全世界光伏产能从2001年的1.3gw增长到2008年的15.2gw。根据“欧洲光伏工业协会

4、”和“绿色和平组织”的一项合作研究预测，如果投资和效率提高继续以目前的速度增长，到2030年，光伏系统将提供2600twh的电量，或者说是全世界人口所需电量的14%。在光伏安装方面，德国、日本和美国似乎正在引领市场；但是，不同报告得出的数字也不尽相同。西班牙已经完成了几个大型光伏电厂的安装工程，2008年总发电能力达到了226.3mw，今年1月份夺得第一名。但是随着个人安装和光伏电厂如雨后春笋般冒出来，光伏市场的布局正在演变，速度之快使得领导地位不断易主。大部分的增长来源于财政激励政策，这些政策通常是以投资补贴的方式进行：返还部分安装成本，或者是当地电力事业单位以收购电价税率的形式从光电生产商

5、那里购买光电。光伏市场对发展中国家而言并非无法触及。研究正在使价格降低，发展中国家也正在获益。在连上电网的成本过于昂贵或者不可能连上的偏远地区，太阳能电力提供了一个优秀的解决方案（见高等专科学校，教奶奶成为太阳能专家）。在这样的地区，已经发展出了一个重要的太阳能充电电池市场。短缺威胁光伏市场标准的光伏组件由单晶和多晶硅做成。组件价格大约有一半取决于经过加工的硅片的成本。1980年，伊曼纽尔萨克斯发明了成串带状晶体生长技术（美国4661200号专利），太阳能电池板行业从此得益于这一重大突破。这个工艺使生产连续的薄条多晶硅片成为可能，消除了之前切割硅棒造成的浪费和巨大费用。生产成本的降低使更广泛应

6、用太阳能技术更加可行。但是晶体硅有很大的缺陷：它的生产是能源密集型，使光伏产业依赖于一种昂贵而稀缺的原材料-硅，光伏制造商必须同微电子产业争夺这种原材料。全世界只有12家工厂在生产光伏级别的多晶硅，当微处理器和光伏市场同时繁荣时，硅价飙升。比如在2004年，因为电子行业的需求很旺盛，硅的成本大幅上涨。因此，在继续进行硅研究的同时，短缺可能带给光伏产业的威胁已经刺激了寻找替代原料的研究。固态物理证明，硅不是光电转换的理想材料。在外太空应用中，所用技术是最先进的，用的也是最纯净的、高性能的硅，其效率大约在30%左右。然而，市场上大部分光伏组件的效率平均在12-18%。效率的提高是业内的头等大事。光

7、电技术的弊端 光电技术的一大弊端是建太阳能电厂所需的土地面积。加利福尼亚计划的550mw太阳能安装项目将占地约25平方公里。不是很多国家有这么多贫瘠不用的废弃土地来建电厂。 安装成本相对而言也很贵，因此要收回成本可能要花多达20年的时间。 太阳能电池板不能在阴天或夜间发电，因此用户必须要么继续使用传统网电，要么安装一个储电系统。 效率提升已露端倪最近转换效率方面的进步靠的是集中太阳光线，与放大镜集中光线来点火用的方式一样。这一方法的结果是需要带有高达30厘米厚的透镜的笨重装置。利用革新的薄膜技术，研究人员在制造比以往都轻便的太阳能电池的同时正在打破转换效率的记录。他们的目的是确定太阳能电池片的

8、理想结构-牢记降低成本、尽可能地缩小尺寸、方便量产的目标。2007年，一个由特拉华大学领导的联合研究机构在一个耗费了21个月的项目中取得了42.8%转换效率的记录，该项目旨在为一种新型高效晶体硅太阳能电池开发技术基础。他们独特的太阳能电池结构融进了光学设计，研制出一种很容易安装在笔记本电脑上的便携小设备（要想了解更多，见pct wo2008/091290)。这个社团的目标是到2010年打破50%的转换效率记录。前景广阔的新材料技术除了在利用硅制造太阳能电池方面有新发展之外，诸如可供选择的半导体和有机化合物等非硅材料也实现了设计突破。因为生产工艺更简单也更便宜，也不争夺硅的使用，所以，使用硅以外

9、的材料可以使成本下降。然而，为了获得甚至超越硅基太阳能电池的效率，尚需进一步研究这些高级材料的使用。这样的研究正如下面例子所显示的那样进展迅速。位于洛桑的瑞士联邦工学院参与的“薄膜光伏”联合研究机构，旨在提高非硅薄膜太阳能电池的效率，特别是所谓的染料敏化太阳能电池，它是由铜铟镓硒化合物制成。2006年项目发布时，cigs薄膜太阳能电池的转化效率达到了11%左右。运用cigs和瑞士联邦工学院获得专利的染料敏化光伏技术，“薄膜光伏”已经在实验室试验中实现了15%的转换效率。但是该联合研究机构相信他们可以获得更好的结果。与硅基薄膜太阳能电池类似，cigs太阳能电池使用厚度达到纳米级别的半导体材料薄层

10、，这种半导体材料可以应用在低成本的衬底上，像玻璃、柔韧的金属片或者箔或者高温聚合物。与传统的光伏技术相反，染料敏化太阳能电池把吸收阳光的任务同电荷载体输送的任务分开来。在染料敏化太阳能电池中，吸光染料因光伏作用产生的电子被传输到运输电荷的半导体材料薄层。这一技术可能的应用之一是染料敏化太阳能电池涂料，它可以直接涂在钢板上，这种涂料由一个英国研究小组开发，有望于2011年投放市场。2008年3月，“美国能源部国家可再生能源实验室”研制的cigs薄膜太阳能电池效率达到了19.9%，打破了“薄膜光伏”的记录。这使薄膜技术同晶体硅具有了同样价值。该实验室宣称，导致功率输出提高的是生产过程中所用材料的品

11、质。该实验室看到了cigs电池的光明前景。因为这种电池重量轻，所以既可以应用于太空，也可以用在便携电子产品市场。这种电池也适合特殊的建筑应用，比如光伏屋瓦和光伏窗户。尽管研究还在初期阶段，非硅薄膜技术已经完成了从实验室到市场的过渡。人们对光伏产业的期望很高。薄膜材料的生产简单而廉价，对环境的影响很低，与柔韧材料兼容，这使得薄膜材料可能用于包装和衣物以及给手机和笔记本电脑充电。光伏市场的发展现在，几种使用单晶硅、多晶硅太阳能电池以及薄膜的太阳能新技术并存于市场，薄膜已经占据了光伏市场的7-10%。“普罗米修斯可持续发展研究所”预测，到2012年，非硅薄膜应用将占到40%的市场份额。目前，美国的生

12、产更多的专注于不同的薄膜技术，欧洲和亚洲则更集中在单晶和多晶硅太阳能电池上。随着研究的进行，效率将进一步提高，前景广阔的其它非硅技术将开始被越来越多地引入市场。正像在wipo即将发行的替代能源技术研究中所示，提交给主要的工业产权机关审理的太阳能发明方面的专利申请数量在过去的20年中增加了近两倍。金融危机正在减慢光伏市场的发展速度，但不会使市场停滞不前。由于技术的改进和新的突破性发明，越来越多已注册的太阳能领域的pct专利证明业内正在取得的进展。在这里，我们只是大体看了一下这一产业的潜力。photovoltaic technology sunny side upthe solar photovo

13、ltaic (pv) market the green energy source par excellence is booming. production has doubled every two years since 2002, making it the fastest-growing energy sector. buoyed by government incentives, the industry is thriving and research is opening new avenues and bringing costs down. the number of so

14、lar energy-related patent applications filed under the patent cooperation treaty (pct) tripled from 2004 to 2008, rising from 460 to 1,411.the photovoltaic effect a phenomenon allowing light-to-electricity conversion was first described by the french physicist edmond becquerel in 1839. albert einste

15、in was awarded a nobel prize for his theoretical work on the subject, published in 1904. intensive research, spurred by the race to space from 1950 to 1969, led a number of companies to develop and bring solar cells, or pv cells, to the marketplace as of 1955. vanguard i, the first solar powered sat

16、ellite, launched in 1958 and ran for eight years. others followed. solar power continues to be used as an auxiliary energy source on spacecrafts and to power orbiting satellites.when it came to earthbound applications, the technology was slower to take off. the return on investment in the pv market

17、did not justify the expense: grid electricity from virtually any other source coal, hydro or nuclear was, and still is, much less expensive. but over the last decade climate change issues have modified our perspective. the environmental problems associated with carbon dioxide (co2) buildup have soun

18、ded an alarm: there is now a pressing need for new, non-polluting technologies as well as revived interest in older technologies that were passed over when cost and mass production were the primary considerations. and so, photovoltaic technology has risen from the dust of patent information stored a

19、nd all but forgotten years ago.from the sun in one hour, the sun provides more than enough energy to supply the earths energy needs for one year. in one day, it provides more energy than the worlds population could consume in 27 years. source: bipv technologypv marketthe “global photovoltaic market

20、analysis and forecasts to 2020” highlights that worldwide pv capacity grew from 1.3 gigawatts (gw) in 2001 to 15.2 gw in 2008. if investments and efficiency gains continue to grow at their current rate, a joint epia* and greenpeace study forecasts that by 2030, pv systems will provide 2,600 terawatt

21、 hours (twh) of electricity or some 14 percent of the electricity needs of the worlds population.germany, japan and the u.s. seem to be leading the market in pv installations, but the figures differ from one report to the next. spain, having completed the installation of several large pv power plant

22、s, with a total generating capacity of 226.3 megawatts (mw) in 2008, laid claim to the number one position in january. but with individual installations and pv power plants mushrooming, the pv landscape is evolving at such a pace that the position of leader is a constantly shifting one. most of the

23、increase is due to financial incentives, which often come in the form of investment subsidies that refund part of the installation costs or in the form of feed-in tariffs where local electric utility companies buy pv electricity from producers.the pv market is not out of the grasp of the developing

24、world. research is bringing prices down and developing countries are benefiting. solar power offers an excellent solution in remote areas too expensive or impossible to connect to the grid (see barefoot college, teaching grandmothers to be solar engineers). in these areas, an important market has de

25、veloped for solar power-charged batteries.scarcity threatens the marketstandard pv modules are made from mono and polycrystalline silicon. some 50 percent of the price of a module is due to the cost of processed silicon wafers. the solar panel industry benefited from a major breakthrough when emanue

26、l sachs invented string ribbon crystal growth in 1980 (us patent 4661200). the process enabled the production of continuous thin strips of multi-crystalline wafers, eliminating the waste and heavy expense previously incurred sawing through blocks of silicon. the reduction in manufacturing cost made

27、wider adoption of the solar technology more feasible.but crystalline silicon has major drawbacks: its production is energy-intensive and leaves the pv industry dependent on silicon an expensive and scarce material for which pv manufacturers must compete with the micro-electronic industry. there are

28、only 12 factories producing pv-grade polycrystalline silicon in the world and when both the micro-processor and pv markets boom, silicon prices skyrocket. in 2004, for example, the cost of silicon significantly increased because demand was high in the electronics industry. so while silicon research

29、continues, the threat that shortages might pose to the pv industry has stimulated a search for alternative materials.solid-state physics has demonstrated that silicon is not the ideal material for light-to-electricity conversion. in applications for outer space, where technology is most advanced and

30、 the very purest, high performance silicon is available, efficiency hovers around 30 percent. but most pv modules on the market average between 12 to 18 percent. improvements in efficiency are a high priority for the industry.photovoltaics the drawbacks one big disadvantage of photovoltaics is the l

31、and area required for a solar power plant. californias planned 550 mw solar installation will cover a surface area of some 25 km2. not many countries have such quantities of barren, unused land to set aside for power plants. installation can also be relatively expensive, so it might take some time u

32、p to 20 years to recoup its cost. it may seem obvious, but solar panels do not produce electricity on overcast days or at night, so user must either stay hooked-up to the regular grid electricity or install a storage system. efficiency gains on the horizonprevious advances in conversion efficiency r

33、elied on concentrating sun rays, in the same way that a magnifying glass concentrates sunlight to ignite a fire. the results were heavy, unwieldy devices with lenses up to 30 centimeters thick. using innovative thin-film technology, researchers are breaking efficiency records while building ever les

34、s cumbersome solar cells. their goal is to define the ideal architecture for the solar cell keeping in mind the objectives of lowering costs, minimizing size and facilitating mass production.in 2007, 21 months into a project aimed at developing the technology basis for a new highly efficient crystal

35、line silicon solar cell, a research consortium led by the university of delaware achieved a record 42.8 percent conversion efficiency. their unique solar cell architecture integrates the optical design with that of the solar cell, resulting in a small, portable device that can easily fit on a laptop

36、 computer (for more information see pct wo2008/091290). the consortium aims to break the 50 percentile marker by 2010.promising new materials technologiesin addition to new developments in the use of silicon for manufacturing solar cells, design breakthroughs have been achieved involving non-silicon

37、 materials including alternative semiconductors and organic chemical compounds. using materials other than silicon can lead to cost reductions because the production process is simpler and less expensive, and does not compete for the use of silicon. however, further research into the use of these ad

38、vanced materials is needed to obtain and surpass the efficiencies of silicon-based solar cells. that research is evolving quickly as shown by the examples below.the thinpv research consortium, in which the swiss federal institute of technology in lausanne (ecole polytechnique fdrale de lausanne (epf

39、l) participates, aims to increase the efficiency of non-silicon thin-film solar cells, specifically copper indium gallium selenide (cigs), organic and so-called dye-sensitized solar cells. at the launch of the project in 2006, conversion efficiency rates of around 11 percent were reached for cigs th

40、in-film solar cells. using cigs and the epfls patented dye-sensitized pv technology, thinpv has already achieved 15 percent efficiency in laboratory tests. but the consortium believes it can achieve much better results.similar to silicon-based thin-film solar cells, cigs solar cells use nano-thin la

41、yers of semiconductor material that can be applied to a low-cost backing, such as glass, flexible metallic sheets or foils, or high-temperature polymers. contrary to conventional pv technologies, dye-sensitized solar cells separate the task of light absorption from that of charge carrier transport.

42、in dye-sensitized solar cells, photogenerated electrons from the light-absorbing dye are passed on to thin layers of semiconductor materials that transport the electrical charge. the possible applications for this technology include dye-sensitized solar cell paints that could be applied directly ont

43、o steel sheets, which are being developed by a u.k. research team. it hopes to bring them to market by 2011.the u.s. department of energys national renewable energy laboratory (nrel) surpassed the thinpv record in march 2008, reaching 19.9 percent efficiency with cigs thin-film. this puts thin-film

44、technology at par with crystalline silicon. the nrel claims that it is the quality of the materials applied during the manufacturing process that boosted the power output. the laboratory sees a bright future for cigs cells; they can be used both in space applications and the portable electronics market because of their light weight. they are also suitable for special architectural uses, such as photovoltaic roof shingles and windows.though still in the early phases of research, non-silicon thin-film technology has already made the transition from the laboratory to the market. ex