首页
登录
职称英语
The need for solar electricity is clear. It is safe, ecologically sound, effi
The need for solar electricity is clear. It is safe, ecologically sound, effi
游客
2023-12-12
19
管理
问题
The need for solar electricity is clear. It is safe, ecologically sound, efficient, continuously available, and it has no moving parts. The basic problem with the use of solar photo-voltaic devices is economic, but until recently very little progress has been made toward the development of low-cost photo-voltaic devices. The larger part of the research funding has been devoted to study of single-crystal silicon solar cells, despite the evidence, including that of the leading manufacturers of crystalline silicon, that the technique holds little promise. The reason for this pattern is understandable and historical. Crystalline silicon is the active element in the very successful semiconductor industry, and virtually all of the solid state devices contain silicon transistors and diodes. Crystalline silicon, however, is particularly unsuitable to terrestrial solar cells.
Crystalline silicon solar cells work well and are successfully used in the space program, where cost is not an issue. While single-crystal silicon had been proven in extraterrestrial use with efficiencies as high as 18 percent, and other more expensive and scarce materials such as gallium arsenide can have even higher efficiencies, costs must be reduced by a factor of more than 100 to make them practical for commercial use. Besides the fact that the starting crystalline silicon is expensive, 95 percent of it is wasted and does not appear in the final device. Recently, there have been some imaginative attempts to make polycrystalline and ribbon silicon, which are lower in cost than high-quality single-crystals; but to date the efficiencies of these apparently lower-cost arrays have been unacceptably small. Moreover, these materials are cheaper only because of the introduction of disordering in crystalline semiconductors, and disorder degrades the efficiencies of crystalline solar cells.
This dilemma can be avoided by preparing completely disordered or amorphous materials. Amorphous materials have disordered atomic structure as compared to crystalline materials; that is, they have only short-range order rather than the long-range periodicity of crystals. The advantages of amorphous solar ceils are impressive. Whereas crystals can be grown as wafers about four inches in diameter, amorphous materials can be grown over large areas in a single process, whereas crystalline silicon must be made 200 micron of the proper amorphous materials in necessary. Crystalline silicon solar cells cost in excess of $ 100 per square foot, but amorphous films can be created at a cost of about 50 cents per square foot.
Although many scientists were aware of the very low cost of amorphous solar cells, they felt that they could never be manufactured with the efficiencies necessary to contribute significantly to the demand for electric power. This was based on a misconception about the feature which determines efficiency. For example, it is not the conductivity of the material in the dark which is relevant, but only the photo-conductivity, that is, the conductivity in the presence of sunlight.
Already, solar cells with efficiencies well above 6 percent have been developed using amorphous materials, and further research will doubtlessly find even less costly amorphous materials with higher efficiencies. (499) [br] The author is primarily concerned with ______.
选项
A、discussing the importance of solar energy
B、presenting a history of research on energy sources
C、describing a possible solution to the problem of the cost of photo-voltaic cells
D、advocating increased government funding for research on alternative energy source
答案
C
解析
在文章的第二句话 The basic problem with the use of solar photo-voltaic devices is economic,but until recently very little progress has been made toward the development of low-cost photovoltaic devices.中作者就指出了本文关注的主要问题,后来的讨论均集中在如何降低这一装置成本的问题上,因此C项是正确答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3266410.html
相关试题推荐
Shortsharptermsmakebigpointsclear.Butpeopleoftenprefertosoftent
Shortsharptermsmakebigpointsclear.Butpeopleoftenprefertosoftent
Shortsharptermsmakebigpointsclear.Butpeopleoftenprefertosoftent
Shortsharptermsmakebigpointsclear.Butpeopleoftenprefertosoftent
Shortsharptermsmakebigpointsclear.Butpeopleoftenprefertosoftent
Theneedforsolarelectricityisclear.Itissafe,ecologicallysound,effi
Theneedforsolarelectricityisclear.Itissafe,ecologicallysound,effi
Theneedforsolarelectricityisclear.Itissafe,ecologicallysound,effi
随机试题
"Equalpayforequalwork"isaphraseusedbytheAmericanwomenwhofeelt
Somepeoplearefriendlydrunks,whereasothersarehostile,potentiallypos
椭圆曲线密码ECC是一种公开密钥加密算法体制,其密码由六元组T=<p,a,b,G
在进行面试,积极的倾听是由下列所有除了?A.演示与生俱来的好奇心。 B.给予适
下列有关公积金的说法,正确的是()。A.法定公积金转为资本时,所留存的该项公
变电站异常及故障处理,详细检查()动作信号、故障相别、故障测距等故障信息
对每笔成交的证券及相应价款进行逐笔交收的主要目的是()。A:防止证券商的信用风险
下列数据特征的测度值中,易受极端值影响的是()。A.中位数 B.众数
施工合同采用可调价合同时,可以对合同价款进行相应调整的情况包括()A、国家规定应
按建标[2003]206号文件的规定,施工机械使用费包括()。A.大型机械
最新回复
(
0
)