1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What is the energy cost of making silicon?

  1. Jan 3, 2017 #1
    I'm trying to determine how much energy it takes to melt down sand into silicon, and convert it to solar panels.

    any info would be great.

    Thanks.
     
  2. jcsd
  3. Jan 3, 2017 #2

    Bystander

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

  4. Jan 8, 2017 #3

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    Are you interested in the energy payback time...

    http://info.cat.org.uk/questions/pv/what-energy-and-carbon-payback-time-pv-panels-uk/

     
    Last edited: Jan 9, 2017
  5. Jan 8, 2017 #4
    Bulk crystalline Silicon is sold for industrial purposes at about 1 or 2 dollars/euro for a Kg, though prices fluctuate of course.
    That's the stuff you need to make solar panels, not melted sand.
    Sand is (mostly) Silicon Dioxide, to make the pure Silicon the oxygen needs to be taken away.
    Usually this is done using Carbon which robs the Oxygen from the Silicon, and releases it as Carbon Oxides.
    I guess the major cost involved in the process would be supplying the heavy duty heating that is needed for the reaction to occur.
     
  6. Jan 9, 2017 #5
    Thank you for the reply. Yes I am trying to find the cost of creating solar panels in terms of carbon and energy. So far it looks like you get about 3 times your investment back out of the solar panels. Of course this depends upon the location of the solar panels. Some countries have better solar exposure. In the early days of solar I heard that there wasn't much benefit besides the off-grid feature of solar panels. I was trying to find out if that was still true.
     
  7. Jan 9, 2017 #6
    Does anyone know the standard rate of repair that the Earth can return carbon dioxide to oxygen?
     
  8. Jan 9, 2017 #7

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    The reference I posted says the energy payback time is around 2.5 to 3.5 years. However the panels might generate for 20 to 25 years. That suggests they produce around 8 times the energy it takes to make them.
     
  9. Jan 9, 2017 #8
    I think it might be difficult to make solar panels from scratch in a small scale workshop, even if you start with already purified Silicon.
    You'll be competing with very large industries (In China especially), who mass produce solar panels and sell them in millions inexpensively.
    You might save some cost by hand assembling banks of photovoltaic cells- the active components of a completed panel into your own panel design.
    The result may not perform any better than the 'off the shelf' panels though.
     
  10. Jan 10, 2017 #9

    CWatters

    User Avatar
    Science Advisor
    Homework Helper

    It appears to be about half the rate we are producing it and reducing according to...

    http://www.smh.com.au/environment/c...de-emissions-says-report-20140909-10ejo1.html

     
  11. Jan 10, 2017 #10

    OmCheeto

    User Avatar
    Gold Member
    2016 Award

    That appears to be about an order of magnitude too low. [ref: $20/kg China] [ref: $11.50-$17.50/kg]
    But I like CWatters reference better: 250 kwh/m2
    Though, it should be noted, that his reference is 9 years old.
    From a website I just found: "the degradation rate is less than 0.5% for panels made before 2000, and less than 0.4% for panels made after 2000. That means that a panel manufactured today should produce 92% of its original power after 20 years" [ref]

    From some silly calculations I've just done, a modern solar panel wont degrade to 50% until it's 125 years old, by which time it will have produced 24,270 kwh of energy.
    Which to me, looks like it will have produced 100 times as much energy as it took to produce it.

    Of course, lots of people want to see a return on their investment, in their lifetime. So this is just "crazy" talk, on my part.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: What is the energy cost of making silicon?
  1. Cost of Compressor (Replies: 2)

  2. What makes light? (Replies: 15)

Loading...