Better Solar Energy Systems: More Heat, More Light

　　Solar photovoltaic thermal energy systems, orPVTs, generate both heat and electricity, but     (51) now they haven’t been very good atthe heat-generating part compared to a stand-alone solar thermal collector.That’s because they operate at low temperatures to cool crystalline siliconsolar cells, which lets the silicon generate more electricity but isn’ta very efficient way to gather heat.

　　That’s a problem of economics. Good solarhot-water systems can harvest much more energy than a solar-electric system ata substantially lower     (53).And it’s also a space problem: photovoltaic cells can take up all thespace on the roof, leaving little room for thermal applications.

　　In a pair of studies, Joshua Pearce, anassociate professor of materials science and engineering, has devised a     (55) in the form of a better PVT made witha different kind of silicon. His research collaborators are Kunal Girotra fromThinSilicon in California and Michael Pathak and Stephen Harrison from Queen’sUniversity, Canada.

　　Most solar panels are made with crystallinesilicon, but you can also make solar cells out of amorphous silicon, commonly knownas thin-film silicon. They don’t create as much electricity, but theyare lighter, flexible, and cheaper. And, because they    (57) much less silicon, they have agreener footprint. Unfortunately, thin-film silicon solar cells arevulnerable to some bad-news physics in the form of the Staebler-Wronski effect.

　　“That means that their efficiency drops when youexpose them to light — pretty much the worst possible effect for a solarcell,” Pearce explains, which is one of the    (60) thin- film solar panels make uponly a small fraction of the market.

　　However, Pearce and his team found a wayto engineer around the Staebler-Wronski effect by incorporating thin-filmsilicon in a new     (62) 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 operatingtemperatures, near the boiling     (63)of water, they could make thicker cells that largely     (64) the Staebler-Wronski effect. Whenthey applied the thin-film silicon directly to a solar thermal energycollector, they also found that by baking the cell once a day, they     (65) the solar cell’s electricalefficiency by over 10 percent.

　　51. A. until                    B.unless                     C. when                      D. if

　　52. A. what                   B.which                     C. that                        D. who

　　53. A. reward                B.bill                         C. pay                         D. cost

　　54. A. move                   B.set                          C. live                         D. take

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

　　56. A. for                       B.by                          C. with                       D. as

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

　　58. A. Unfortunately     B. Certainly                C.Luckily                  D. Immediately

　　59. A. cover                   B.relate                      C. face                        D. expose

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

　　61. A. part                     B.result                      C. subject                   D. way

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

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

　　64. A. promoted            B. improved               C.overcame               D. asserted

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

　　参考答案：

　　51-55ABDDC    56-60 DCADC    61-65 DABCA

试卷代码：12

　　试卷级别：理工A

　　本人已通过专八，我的答案是：

　　1-5  　ADBBB

　　6-10   BACAB

　　11-15　CADBB

　　16-20　CABAA

　　21-25　CADCE

　　26-30　ABCDE

　　31-35　DDADC

　　36-40　BDDCD

　　41-45　BACBA

　　46-50　AEFBC

　　51-55　ABDDC

　　56-60　DCADC

　　61-65　DABCA