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Why are triple junction solar cells so expensive to manufacture?

Discussion in 'Photovoltaics' started by Robert La Ferla, Nov 22, 2005.

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  1. Why are triple junction solar cells so expensive to manufacture? Why
    can't solar cell manufacturing mimic Moore's law? There's certainly
    enough customers. i.e. Every needs electricity.
  2. Where does gallium arsenide come from? Why is it more costly? And why
    is the process more costly?
    I'm only making a comparison that when there is investment in research,
    you get results.
  3. Me

    Me Guest

    Robert La Ferla
    simply beacause there is a GIANT difference in the number of engineers
    working on Computing Power as opposed to Solar Power.........

    the same is true for invested capital for the two industries........

    Me who doesn't need a Rocket Scientist to figure that one out.....
  4. Guest

    I noted a statement in this group a while ago that most PV panels are made
    with reject silicon from integrated circuit manufacturers. If that's the
    case, the silicon PV is starting with recycled materials that have already
    gone through some of the expensive manufacturing process. That would keep
    their price lower compared to cells made from raw materials.
  5. Thanks. This is the sort of detailed response I was looking for.
  6. Guest

    Gallium's also fairly rare and expensive compared to silicon, no?

  7. SJC

    SJC Guest

    Gallium's also fairly rare and expensive compared to silicon, no?


    I know from reading that Indium is in limited supply. They use it in CIGS
    thin film designs and it looks like Specrolab uses it in the multiple junction
    cells as well.

    I think an interesting question is why don't they make silicon multiple junction
    cells. Unisolar makes a thin film cell that converts red, green and blue
    wavelengths of light, using amorphous silicon on a panel.
  8. SJC

    SJC Guest

    Thanks for the explaination. I was looking at bifacial solar cells
    and wondered why mutiple junction silicon wafer cells were not possible.

    In order to make a multijunction solar cell, you need materials with
    different band gap energies. Since the band gap energy is a material
    property, this implies that multijunction cells can only be made with
    multiple materials. While Unisolar calls their triple-junction cell an
    amorphous silicon cell, only one of the layers in the cell is what one
    normally thinks of when one thinks of an amorphous silicon solar cell.
    The other two layers are amorphous silicon alloyed with other materials
    -- in this case germanium -- to alter the band gap.

    The reason Unisolar can do this inexpensively is that they are using
    inexpensive manufacturing methods that produce amorphous materials. In
    order to get the advantages of crystalline silicon in a multijunction
    device, the device must be made with crystalline silicon. This can only
    be done by using crystalline silicon with other materials, or by
    alloying silicon with other materials to alter its band gap and
    crystallizing it. I am not aware of anybody who has done the former
    successfully, though Sanyo comes close with its HIT cell design (which
    uses a *single* junction formed from two different materials). The
    latter would, to my knowledge, require very expensive production
    techniques along the lines of those used to make GaAs.
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