Use Of Tandem Solar Cells For Absorbing More Light


Gail Alvares talks to Niraj Lal, a scientist on the discovery of a new material in the solar cells that comes with specific light wavelengths. The sunlight absorbed by the silicon solar cells like the infrared light coming with 1-micrometer wavelength. Remember sunlight is high in energy and it needs to be captured. Nij is currently developing materials for the efficient capture of sun’s energy especially in the visible range of approximately 400-800nm. Nij’s idea is developing a tandem cell capable of capturing short wavelength light allowing infrared beams to pass through to be captivated by the silicon cell.

solarsystemTandem solar cells are crystalline silicon presenting low-cost solar cells with projected efficiencies of over 30%. The dual junction solar cell configuration consists of the c-Si bottom cell of high efficiency and a thin film cell that is made of low-cost materials. To reach the minimum efficiency it is important to reach 30% tandem efficiency ranging from 22% to 14% with a bandgap of 1.5 eV to2 eV respectively. The material needs are defined using a simple model with four terminal tandem in terms of the electronic band gap, luminescence, optical absorption and carrier transport.

So tandem solar cells are the latest entrant in the field of solar technology for powering up homes.

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Is Electronic Voting Trustworthy?


The electronic voting system is being followed in developed and developing democracies across the globe during elections. The voting system ensures there is no duplication and the voter rolls are verified. The counting process is hastened with optical scanners. The doubts that arise is if the voting can be done online or should the voter visit the voting booth to cast their votes? Is online voting secure? Can hacking prove detrimental to the voting system? These are some of the questions that need an answer. The discussion will be related to this topic.

With everything going online today, electronic voting is going to change the political scenario. Governments across the globe are taking a call on online voting and the trial has already begun. Critics have always cautioned on the electronic voting system calling it insecure for our democracy. The United Kingdom ran trials on the electronic voting for their local elections during the years 2002, 2003 and in 2007. Estonia was the first country to go online for voting for their general elections in the year 2007.

electricA research by the WebRoots Democracy informs that there is a higher chance of young voters voting if the voting system goes online. Moreover, the cost incurred for the election could be drastically brought down with the online voting system. Though some security concerns do arise despite there were no attacks on the e-voting system. But it is not denied that the e-voting system may become vulnerable to attacks if the system is widespread.

Besides securing the e-voting system from malware and other related threats it has to be protected from manipulations. There are no signatures to authenticate the voter, very similar to the postal ballot system. With this said e-voting is not completely free from malpractices. Cyber security issues are also a cause for concern in the electronic voting system. It could be scary and make democracy a gamble.

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Jack Kaye On Discover satellite


There are thousands of satellites in the orbit moving around the earth. There are 2,271 satellites in the orbit listed by Gobbard Space Flight Center. Russia has over 1,324 satellites in the orbit and the US has 658 to its credit. GPS runs on the information given by the satellites and it is the foundation of modern communication. Without satellites, we cannot monitor the meteorological happening and other surface conditions. Talk to Jack Kaye on the imaginary uses of the satellite. Jack is from the NASA Earth Science Division.

sateliteJack Kaye is the member of Senior Executive service. He was earlier associated with Goddard Space Flight Center, managed the Atmospheric Chemistry Modeling and Analysis Program at the NASA HQ. Jack talks about the images of the moon taken from the Discover satellite launched the year before. He says space allows you to look at earth differently. Though the picture is the backside of the moon, it is actually the front for the satellite, informs Jack.

The complexity of the Earth is drawn from the oceans, clouds, greenery, brown areas and the photograph was taken some millions of miles away from the earth. Jack says the Discover satellite has two instruments, one is the EPIC, camera for the images that captures the pictures and the other is for Earth radiation budget. The Discover satellite was launched by the NOAA, the Department of Defense and the NASA last year.

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