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Course: NOVA Labs > Unit 1
Lesson 5: Energy- Growing appetites, limited resources
- Growing appetites, limited resources quiz
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Solar power
The Sun is a reliable energy source that we can harness and convert into electricity in several ways. So why are renewable and clean solar energy systems not used more widely? Created by NOVA.
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At0:54, the video says that most photovoltaic cells are made of silicon. What are other PV cells made from, and why is that other material used instead?(3 votes)
95% of the PV market is taken by silicon solar cells (source Fraunhofer 2017 report). The remaining 5% are thin film technologies, with CdTe being the main commercialized technology. The reasons for using other materials is that silicon has a low "light absorption coefficient", which means that you need a quite thick piece of silicon to properly absorb all the light (typically ~150 micrometers thick). It would be better to use a material with a high absorption coefficient, like CdTe, CIGS or Perovskites, because then you can have very thin films (hence the name thin film solar cells). Efficiency, stability, cost and toxicity are reasons why these technologies are not yet taking over the market.(2 votes)
Can somebody explain to me why we have to make double conversion in space? I cannot seem to find the actual reason. Thanks in advance. :)(2 votes)
Do solar panels have to be replaced, since the electrons are knocked out of the silicon atoms inside them? (1:05)(2 votes)- Even though electrons are "knocked out" of the silicon material they are actually returned on the other side. Just like with batteries you need to connect both minus and plus poles of the solar cell to have the current run (you need to close the circuit). When electrons with high energy leave the minus pole, electrons with a lower potential energy come through the plus pole. That way, the material is not destroyed when it is generating a current. Silicon solar cells degrade over time though, and water seeping in through the seals is one of the problems.(2 votes)
- Is it possible to make electricity from sound energy as sound energy produce vibrations and we can use these vibrations to make electricity. But the problem which you people are thinking about is that there is a very little energy in sound so how can we use it so my answer is we can place that inverter or what you say like converter of sound energy into electrical energy in a football or cricket stadium where there is too much sound energy so what you people think about it GREEN ENERGY PROJECT.(2 votes)
- Please can someone tell me why this statements true? When it comes to solar cells and choosing the materials.
"The materials used for the two junction-forming layers must be dissimilar to the absorber in order to produce the built-in electric field and to carry the electric current", Britannica(2 votes) - why do the manufacturing of solar products is costly?(2 votes)
- For silicon solar cells, the material (silicon) needs to be very pure and have few other elements in it. To purify the material, the silicon needs to be melted (1414ºC is the melting temperature) and grown into crystals. It takes a large amount of energy to make the crystaline silicon wafer. After that, you need a very clean production facilities, and expensive equipment to make a solar cell of those wafers. You can read more about that on PV-education: https://www.pveducation.org/pvcdrom/manufacturing-si-cells/refining-silicon(1 vote)
- roulette panels work at night?(1 vote)
At2:19"Even if you plaster every hous with solar panels, it still would not replace fossil fuel.."
But you could build zero-energy buildings and save energy?
https://en.wikipedia.org/wiki/Zero-energy_building(1 vote)
At2:13Tesla has begun to solve this problem with their powerwall. What can we as consumers do to assist in these efforts to solve the problems of energy storage and lowering the costs of PV production?(1 vote)
Why most of the photovoltaic cells are made up of silicon and not by any other element?(1 vote)- recent commercial productions are dominated by silicon, but actually there are many types of semiconductors other than silicon are being developed, including TiO2, CdTe, and ZnO(1 vote)
0:54