Κυριακή, 10 Απριλίου 2011

Advanced solar cells to provide with more heat and electricity

solar cell

Going green and reducing the emission of greenhouse gases has been our motto for quite some time now. But the truth is renewable forms of energy are yet to leave a firm footprint in our lives so that our carbon footprints start disappearing. Solar energy is one such example which has tremendous potential but is yet to be harnessed. The first generation photovoltaic cells were developed in Bell laboratories in 1954. So the concept and technology goes back quite some time in history. But still we are plagued by concerns of reduced efficiencies and intermittent supply concerns. These are eternal problems that have kept the solar market from booming.
However, Professor David Faiman, the director of the National Solar Energy Center and associated with Ben-Gurion University have found a way to make proper use of a “thousand splendid suns”. And this has got less to do with literature and more to do with science and tech.

Fairman and his start-up company Zenith Solar (of Israel) using its Z20 technology has come up with Concentrated Photovoltaic systems (CPV). Each of the CPV cells can generate 5kW of heat and 2kW of power. Hence, the efficiency of the solar cells is increased manifolds and they are being used to generate power and feed the national grid of Israel. The CPV systems consist of reflective mirrors made of silicon that concentrates the rays falling on the large reflector dishes on the solar cells. However, the system gets heated up and needs to be cooled by water. This water is then directed to a heat exchanger and used at site.
Using this Z20 technology, Kibbutz Yavne in Israel is producing and selling electricity to the national grid and providing hot water for 220 community residents. Hence this can be used on a larger scale worldwide. It has another advantage of reduced cost.
Fairnam says,
“Traditional photovoltaic cells do two things: collect sunlight and generate electricity from it. What we’ve done is simply split those two functions, so that the sunlight is collected and concentrated by a dish-shaped mirror, and a small number of concentrator cells generate electricity from that highly concentrated sunlight. Photovoltaic material is far too expensive to waste on something that can be accomplished with cheap glass and steel.”
The CPV receiver only comprises 5% of the overall cost. Also, it requires less land to set up the facility. However, some disadvantages remain. For instance, in case of cloud cover the receptors’ efficiency reduces drastically. This “shadow effect” has been a perennial problem for solar cells. But I guess even the bright sun has its own spots. What matters is how we work around our problems and look at the bigger and brighter picture!

http://www.ecofriend.com/entry/advanced-solar-cells-to-provide-with-more-heat-and-electricity/

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