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Better Solar Energy Systems: More Heat, More Light

Solar photovoltaic(光伏的)thermal energy systems,or PVTs, generate both heat and electricity, but until 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(晶体的)silicon solar cells, which lets the silicon generate more electricity but isn'ta very efficient way to gather heat.

That's a problem of economics. Good solar hot-water systems can harvest much more energy than a solar-electric system at a substantially lower cost. 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 solution in the form of a better PVT made with a different kind of silicon. His research collaborators are Kunal Girotra from Thin Silicon 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(非晶体的)silicon, commonly known as thin-film silicon. They don't create as much electricity, but they are lighter, flexible, and cheaper. And, because they require much less silicon,they have a greener footprint. Unfortunately, thin-film silicon solar cells are vulnerable to some bad-news physics in the form of the Staebler-Wronski effect.

"That means that their efficiency drops when you expose them to light—pretty much the worst possible effect for a solar cell," Pearce explains,which is one of the reasons 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 type 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 point of water, they could make thicker cells that largely overcame the Staebler-Wronski effect. When they applied the thin-film silicon directly to a solar thermal energy collector, they also found that by baking the cell once a day, they boosted the solar cell's electrical efficiency by over 10 percent.

31.【题干】PVTs are not efficient in_____在哪方面效率不高的

【选项】

A.creating electricity. 产电

B.cooling silicon solar cells.冷却硅太阳能电池

C.generating heat.产能

D.powering solar thermal collectors. 太阳热能集电极

【答案】C

32.【题干】One of the problems PVTs have is that_____

【选项】

A.their thermal applications are costly. 他们的热能应用太贵了

B.they are too expensive to afford. 太贵承担不起

C.it is hard to fix them on the roof. 在房顶上很难修理

D.they occupy too much space. 占空间

【答案】D

33.【题干】Which of the following is NOT mentioned as an advantage of thin-film silicon solar cells? 薄膜硅太阳能电池的优点 以下不是的是

【选项】

A.They are flexible. 灵活的

B.They are less expensive. 没那么昂贵

C.They are electrically efficient. 电效率高的

D.They are environment friendly. 环保的

【答案】C

34.【题干】Thin-film solar panels do not sell well on market because_____

【选项】薄膜太阳电池板市场卖的不好是因为

A.they do not work well if exposed to light. 接触到阳光 运作不好

B.their advantages are not well-recognized. 他们的优点没被很好的认可

C.they need improving in appearance.外观需要提升

D.they are not advertised. 没有做广告

【答案】A

35.【题干】Which of the following statements is true?

【选项】

A.New techniques have been developed to produce thin-film silicon. 没有发明新技术来生产薄膜硅 没有提及新技术 错误

B.Thin-film silicon works efficiently at low temperature. 薄膜硅在低温下运作效率高 错 You don't have to cool down thin-film silicon to make it work 没有必要冷却他来使得他运作

C.Thin-film silicon's electrical efficiency improves when heated up. 加热时，薄膜硅的电效率提升。

D.A new material enlarging the Staebler-Wronski effect has been created.扩大SW 效应的新材料被创造出来。

【答案】C

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