SOLAR CELL: The silicon in photovoltaic cells transforms incoming light into electricity rather than heat.
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The sun—that power plant in the sky—bathes Earth in ample energy to fulfill all the world's power needs many times over. It doesn't give off carbon dioxide emissions. It won't run out. And it's free.
So how on Earth can people turn this bounty of sunbeams into useful electricity?
The sun's light (and all light) contains energy. Usually, when light hits an object the energy turns into heat, like the warmth you feel while sitting in the sun. But when light hits certain materials the energy turns into an electrical current instead, which we can then harness for power.
Old-school solar technology uses large crystals made out of silicon, which produces an electrical current when struck by light. Silicon can do this because the electrons in the crystal get up and move when exposed to light instead of just jiggling in place to make heat. The silicon turns a good portion of light energy into electricity, but it is expensive because big crystals are hard to grow.
Newer materials use smaller, cheaper crystals, such as copper-indium-gallium-selenide, that can be shaped into flexible films. This "thin-film" solar technology, however, is not as good as silicon at turning light into electricity.
Right now, solar energy only accounts for a tiny portion of the U.S.'s total electricity generation, because it is more expensive than alternatives like cheap but highly polluting coal. Solar power is about five times as expensive as what people pay for the current that comes out of the outlets.
In order to have a hope of replacing fossil fuels, scientists need to develop materials that can be easily mass-produced and convert enough sunlight to electricity to be worth the investment.
We asked Paul Alivisatos, deputy laboratory director at Lawrence Berkeley National Laboratory in California and a leader of their Helios solar energy research project, to explain how people capture energy from sunlight and how we can do it better.
[An edited transcript of the interview follows.]
What is a solar cell?
A solar cell is a device people can make that takes the energy of sunlight and converts it into electricity.
How does a solar cell turn sunlight into electricity?
In a crystal, the bonds [between silicon atoms] are made of electrons that are shared between all of the atoms of the crystal. The light gets absorbed, and one of the electrons that's in one of the bonds gets excited up to a higher energy level and can move around more freely than when it was bound. That electron can then move around the crystal freely, and we can get a current.
Imagine that you have a ledge, like a shelf on the wall, and you take a ball and you throw it up on that ledge. That's like promoting an electron to a higher energy level, and it can't fall down. A photon [packet of light energy] comes in, and it bumps up the electron onto the ledge [representing the higher energy level] and it stays there until we can come and collect the energy [by using the electricity].
What's the biggest difference between how a plant captures light energy and how we do it with solar cells?
We wish we could do what plants do because plants absorb the light, and [they use] that electron to change a chemical bond inside the plant to actually make fuel.
Could you do artificial photosynthesis and emulate a plant?
We would love to be able to make a solar cell that instead of making electricity makes fuel. That would be a very big advance. It's a very active topic right now among researchers, but it's hard to predict when we will be able to use it.
See what we're tweeting about
29 Comments
Add Comment'Scientists mimic essence of plants' energy storage system!'
Reply | Report Abuse | Link to thisAn MIT professor has been working on an artificial photosynthesis type energy system that could revolutionize solar technology.
http://web.mit.edu/newsoffice/2008/oxygen-0731.html
It still may be some time before commercial use is realized but it is exciting none the less.
How expensive would it be to try to make the solar cells more efficient at capturing the light and then converting it into electricity? Maybe we should be looking into that and not just other technologies. Once we've found a good source, and a reasonably effective one, we Should try to better it and by doing so we will save money in the long run. I still think that constant research is a must but I don't see a reason to completely abandon what we've started!
Reply | Report Abuse | Link to thiswhy is it that the amount of solar energy generated not enough?is it that the intensity of the sun rays over there not is much?
Reply | Report Abuse | Link to thisThat we have not yet utilised a resource we know is < for all intents and purposes> limitless, is a telling tale of us as a species. We kill ourselves over something exhaustible, and stifle developement < by inaction and negative action > of technologies we know will make all our lives better.
Reply | Report Abuse | Link to thisIn the time it takes you to login and comment you can do a few things:
Reply | Report Abuse | Link to this1) Look up the average power per square meter of sunlight hitting the earth.
2) Look up the average efficiency of cutting edge solar panel technology
3) Look up the annual energy consumption per capita/of the US/of the world.
4) Calculate the size of an international sea based solar panel stationed at the equator!
We have limited ourselves to high tech companies researching solutions for us. Have we considered other alternate technologies to generate power, like solar telsa turbines? Anyone can make one of these and they generate more useable, cheaper, and much easier to produce energy than photovoltaics. Energy that anyone can produce with few simple parts as opposed to a few companies producing expensive solar panels. Any suggestions why researchers research projects few will be able to build?
Reply | Report Abuse | Link to thisi said how dose solar power work in nature
Reply | Report Abuse | Link to thisComment by Ron Walkr (Ron Walker) 10-20-2008 02:17pm. Are you the same Ron Walker who owns a company called Australian Nuclear Energy . The same Ron Walker who has been lobbying for nuclear power industries in Ausralia? Of course you believe it should be "part of the persuasion" sorry "equation". Perhaps an unfortunate coincidence of birth name,perhaps not.
Reply | Report Abuse | Link to thisWhat about solar power, we could use that.
Reply | Report Abuse | Link to thisWhy don,t we just use solar powered energy
Reply | Report Abuse | Link to thishow can we build a simple system? and what is the assurance n ROI?
Reply | Report Abuse | Link to thisCan someone tell me w r t the Return on Investment (ROI) ...once convinced .....I would seriously get into this
Reply | Report Abuse | Link to thisROI -can i have more info on te returns on investment...I can even go in a big way to produce these system...commercial purpose.
Reply | Report Abuse | Link to thisthank you for trying to make gobal warming stop and looking for a way to not create co2 in our air and gas and another way to get fuel but i advise u if u found some powerful engry force a way i rekon u could really help our world is to use another type of engry for a motor (car Transport) instered of using fuel could u try to crerate some kind of mineral to crerate liqurad of engry or a engry that make a exsplostion from a spark plug or any other way to make a exsplostion. if u done that u would make history of man kind if u found some way if u found a sorce of energy thank you if u read this by Damon hayden.
Reply | Report Abuse | Link to thisthank you for trying to make gobal warming stop and looking for a way to not create co2 in our air and gas and another way to get fuel but i advise u if u found some powerful engry force a way i rekon u could really help our world is to use another type of engry for a motor (car Transport) instered of using fuel could u try to crerate some kind of mineral to crerate liqurad of engry or a engry that make a exsplostion from a spark plug or any other way to make a exsplostion. if u done that u would make history of man kind if u found some way if u found a sorce of energy thank you if u read this by Damon hayden.
Reply | Report Abuse | Link to thisthank you for trying to make gobal warming stop and looking for a way to not create co2 in our air and gas and another way to get fuel but i advise u if u found some powerful engry force a way i rekon u could really help our world is to use another type of engry for a motor (car Transport) instered of using fuel could u try to crerate some kind of mineral to crerate liqurad of engry or a engry that make a exsplostion from a spark plug or any other way to make a exsplostion. if u done that u would make history of man kind if u found some way if u found a sorce of energy thank you if u read this by Damon hayden.
Reply | Report Abuse | Link to thisthank you for trying to make gobal warming stop and looking for a way to not create co2 in our air and gas and another way to get fuel but i advise u if u found some powerful engry force a way i rekon u could really help our world is to use another type of engry for a motor (car Transport) instered of using fuel could u try to crerate some kind of mineral to crerate liqurad of engry or a engry that make a exsplostion from a spark plug or any other way to make a exsplostion. if u done that u would make history of man kind if u found some way if u found a sorce of energy thank you if u read this by Damon hayden.
Reply | Report Abuse | Link to thisHere is a really cool video that explains the whole process and a history of how the whole solar energy concept was created and where we are at now...
Reply | Report Abuse | Link to thisLook here:
http://www.yoursolarlink.com/how-does-solar-power-work
Coll video/animation and explanation on "How Does Solar Power Work" here:
Reply | Report Abuse | Link to thishttp://www.yoursolarlink.com/how-does-solar-power-work
im doing a history report on solar power and i cant find anything for it beside the stuff saying solar panles and how they work but i need facts about the plain solar power help!
Reply | Report Abuse | Link to thisWhat is the advantages of solar generator?
Reply | Report Abuse | Link to thisSolar generator is an environmental friendly equipment that can use anywhere. You can save the earth by having good equipment like a solar generator. What are the advantages of a solar generator? If you don't know, check out sunpowerport.com. The featured generator will run most small electrical appliances. It is great for camping or emergency backup. No noise. No fumes. For more details see http://www.sunpowerport.com
weell solar energy is offfff the hizzy fo shizzy dawg
Reply | Report Abuse | Link to thisI'm not a scientist. When I was a kid we used a magnifying glass to do silly stuff like burn ants and cause matches to ignite. Could it be as simple as an old fashion boiler using water, not silicon chips, that create old fashioned steam thus driving turbines that create electricity?
Reply | Report Abuse | Link to thisRegardless of what anyone says..solar just makes sense so it's time we start moving forward.
Reply | Report Abuse | Link to thishttp://www.sunriseenergynow.com
A question. If the photon excites the electron into jumping over the band gap (if there is complete circuit)what happens to that electron if there is not place to go (no complete circuit) what happens to that energy?
Reply | Report Abuse | Link to thisI'm not going to say what everyone else has already said, but I do want to comment on your knowledge of the topic. Youre truly well-informed. I cant believe how much of this I just wasnt aware of. Thank you for bringing more information to this topic for me. Im truly grateful and really impressed.Recommend a solar water heater production sites: http://www.ejaisolar.com/
Reply | Report Abuse | Link to thisI think that the solar power works with the sun. I read this article http://www.sunpowerport.com for additional information how the solar power works.
Reply | Report Abuse | Link to thiswe will be dead :l living creatures and plants cannot survive without light and heat.
Reply | Report Abuse | Link to thisTo be honest, this method isn't exactly free. The renewable energy source (solar) may be, but to convert it to electricity using solar panels costs a great amoutn of money, and it takes years to generate enough energy to get your money back :L
Reply | Report Abuse | Link to this