Better Solar Energy Systems: More Heat, More Light

　　Solar photovoltaic thermal energy systems, or PVTs, generate both heat and electricity, but __1__ now they haven’t been very good at the heat-generating part compared to a stand-alone solar thermal collector. That’s because they operate at low temperatures to cool crystalline silicon solar cells, which lets the silicon generate more __2__ but isn’t a very efficient way to gather heat.

　　That’s a problem of __3_ . Good solar hot-water systems can harvest much more energy than a solar-electric system at a substantially lower __4__. And it，s also a space problem：photovoltaic cells can take up all the space on the roof, leaving little room for thermal applications.

　　In a pair of studies, Joshua Pearce, an associate professor of materials science and engineering, has devised a __5__ in the form of a better PVT made with a different kind of silicon. His research collaborators are Kunal Girotra from ThinSilicon in California and Michael Pathak and Stephen Harrison from Queen’s University, Canada."

　　Most solar panels are made with crystalline silicon，but you can also make solar cells out of amorphous silicon, __6__ known as thin-film silicon. They don’t create as much electricity, but they are lighter, flexible, and cheaper. And, because they __7__ much less silicon, they have a greener footprint. Unfortunately，thin-film silicon solar cells are __8__ to some bad-news physics in the form of the Staebler-Wronski effect.

　　“That means that their efficiency __9__ when you expose them to light — pretty much the worst possible effect for a solar cell,” Pearce explains，which is one of the __10__ thin- film solar panels make up only a small fraction of the market.

　　However, Pearce and his team found a way to engineer around the Staebler-Wronski effect by incorporating thin-film silicon in a new __11__ of PVT. You don’t have to cool down thin-film silicon to make it work. In fact，Pearce’s group discovered that by heating it to solar-thermal operating temperatures，near the boiling __12__ of water, they could make thicker cells that largely __13__ the Staebler-Wronski effect. When they applied the thin-film silicon directly to a solar thermal energy __14__ , they also found that by baking the cell once a day，they __15__ the solar cell’s electrical efficiency by over 10 percent.

　　词汇:

　　photovoltaic n.光电的

　　silicon n.硅

　　thermal adj.热的，热量的

　　amorphous adj.非晶形的

　　crystalline adj.晶体的

　　footprint n.足迹

　　注释：

　　1. solar photovoltaic thermal energy systems:太阳能光伏热能系统

　　2. they: 指代 solar photovoltaic thermal energy systems。

　　3. stand-alone:单机的

　　4. crystalline silicon solar cells:晶体硅太阳能电池

　　5. which:指前半句中的to cool crystalline silicon solar cells 这件事

　　6. room:空间

　　7. solar panels:太阳能电池板

　　8. amorphous silicon：非晶硅

　　9. thin-film silicon:薄膜硅

　　10. Staebler-Wronski Effect: SWE效应。在光的照射下，非晶桂氢的导电性短时间内显著衰退，这种特性被称为SWE效应o

　　11. pretty much:几乎

　　12. the worst possible effect：最可能坏的效应

　　13. engineer around:精心地设计以克服或绕过

　　14. solar-thermal operating temperatures:太阳热能操作温度

　　练习：

　　1. A. unless B. when C. if D. until

　　2. A. electricity B. magnetism C. ultraviolet D. radioactivity

　　3. A. dynamics B. geology C. economics D. biology

　　4. A. reward B. cost C. bill D. pay

　　5. A. decision B. solution C. suggestion D. qualification

　　6. A. roughly B. probably C. commonly D. specially

　　7. A. retrieve B. merge C. exchange D. require

　　8. A. vulnerable B. necessary C. important D. renewable

　　9. A. works B. counts C. rises D. drops

　　10. A. restrictions B. advances C. reasons D. strengths

　　11. A. size B. shape C. type D. brand

　　12. A. area B. point C. place D. extent

　　13. A. overcame B. promoted C. improved D. postponed

　　14. A. transformer B. adaptor C. transmitter D. collector

　　15. A. boosted B. defined C. wasted D. lower

　　答案与题解：

　　1. D文章介绍最近科学家已经完善了太阳能光伏热能系统，现在新型的太阳能系统能将太阳能转换为更多的电能和热能。第一段说明以往晶体硅太阳能电池在收集热能方面效率很低。四个选项中，只有选用until才符合上下文的意思。“...until now they (太阳能光伏热能系统) haven’t been very good at the heat-generating part compared to a stand-alone solar thermal collector. ”该句意为：与太阳热能单机集热器相比，直到现在，传统太阳能光伏热能系统在转换热能方面效率一直不是很高。

　　2. A本句说明了以往的太阳能光伏热能系统在转换热能方面效率低的原因，“to cool crystalline silicon solar cells(冷却晶体桂太阳能电池)”能产生更多的电能，但不利于收集热能。electricity是答案。

　　3. C从上一段和本段的意思判断，收集热能效率低下不会是一个动力学(dynamics)问题，地质(geology) 问题或生物学(biology)问题。它是一个经济上的问题。答案是economics。

　　4. B 本句说，good solar hot-water systems 在收获能量方面比solar-electric system 要好得多。从经济学的角度上分析，成本就降低了。所以，选cost是对的。其他选项reward，bill和pay均不符合句意。

　　5. B上一段说光伏电池系统有两个问题，即经济问题和空间问题。Joshua Pearce采用另外一种硅制造PVT来解决上述问题。通过上述分析可以看出，他寻求的是一种解决问题的办法(solution)，而不是一个决定(decision)、一个建议(suggestion )或一种资格( qualification)。

　　6. C amorphous silicon (非晶硅)即为thin-film silicon (薄膜硅)。选择roughly/probably/ wrongly( known as thin-film silicon)表达的意思都不合逻辑。选commonly才合理。"amorphous silicon, commonly known as thin-film silicon” 意为“非晶硅，通常被称为薄膜硅”

　　7. D新型的太阳能电池采用薄膜硅制造,电能的转换量虽然不如晶体硅太阳能电池，但薄膜硅太阳能电池用硅量小，比较环保。本题应选用require，理由是:require much less silicon与上下文的意思很连贯，而retrieve much less silicon (提取少得多的硅)，merge much less silicon(混合少得多的硅)或exchange much less silicon(交换少得多的硅)都讲不通,意思离题太远。

　　8. A bad-news physics是解题的关键词。既然是bad-news physics, 所连用的形容词应该是负面意义的词。四个选项中只有vulnerable(易受攻击的)符合这个条件，所以是答案。

　　9. D本段第一句说明vulnerable的具体情况。既然是vulnerable，efficiency—定是drops，不会是rises。efficiency works(效率起作用)或efficiency counts(效率有重要意义)都离题太远。

　　10. C薄膜硅太阳能电池效能低下，这是因。导致该产品市场占有份额很小，这是果。选reasons为答案很合理。

　　11. C为了克服SWE效应，Pearce和他的团队悉心改进光伏太阳热能系统的结构。作者要写的应该是a new type of PVT(—种新型PVT)，不会是a new shape/size/brand PVT(—种新形状的/新尺寸的/新品牌的PVT)。

　　12. B 从上下文判断，答案应该是point。将thin-film silicon 加热到solar-thermal operating temperatures 就是加热到near the boiling point of water(临近水的沸点)。其他选项area, place和extent均不切题。

　　13. A从上下文判断，采用加热thin-film silicon的方法，就能消除SWE效应。四个选项中只有overcame表达了这层意思。

　　14. D答案是collector,因为solar thermal energy collector(太阳能集热器)与上下文的意思接得上，意为“当把薄膜硅直接应用于太阳能集热器时”。其他选项均与上下文不符。

　　15. A文章最后一段介绍研究人员克服SWE效应，提高了将太阳能转换为电能的效率。所以，将最后一句的“by 10 percent”理解为“提高”而不是“降低”10%才合乎逻辑。答案是boosted。