Project Overview
  As a group we decided to go the analytical route. The 
   purpose of our project was to investigate the physics of 
   solar panels including their production and how they 
   convert light to energy. Also investigated are their 
   efficiency and efficacy as long-term “green” solutions as 
   well as some of the political implications of their use.
         The Raw Materials Required for Solar Panels
         •   There are several varieties of cells today that can be used to absorb sunlight and convert those photons 
             into electrical energy. These include:
               – CIS (Copper Indium Diselenide) Cells
               – CdTe cells (Cadmium Telluride) Cells 
               – Organic Cells
               – Multi-junction Cells
         •   Although multi-junction cells have the highest efficiency among solar cells achieved in a laboratory 
             setting (demonstrated by the following graph), Silicon Cells (monocrystaline, polycrystaline and 
             amorphous) due to their low cost and decent efficiency are the most feasible for wide production and 
             will thus be the main interest of our study. 
                                                                                  What’s in a Polycrystalline Si Solar Cell?
                                                                                                                            
                                                                                                                            
                                                                                -Polycrystalline cells are slightly 
                                                                                less efficient than monocrystalline 
                                                                                solar cells, but are cheaper to 
                                                                                manufacture in wafer form.
                                                                                -The diagram below from How 
                                                                                Stuff Works illustrates the order of 
                                                                                the raw ingredients needed to 
                                                                                create a generic polycrystalline 
                                                                                silicon cell. 
                                                                                They include:
                                                                                A. A layer of glass for protection
                                                                                B. Antireflective coating
                                                                                C. Contact grid
                                                                                D. Highly purified N-Type Silicon
                                                                                E.   P-Type Silicon
                                                                                F.   Back Contact.
       Raw Materials Continued
   • There is no threat to the global supply of any 
    of the raw materials used to manufacture 
    silicon solar cells, even if their production 
    dramatically accelerated. 
   • Silicon is an abundant element in the earth’s 
    crust, and is in no way potentially threatened 
    with shortage. 
   • There is some concern about the supply of 
    materials needed for non-silicon based cells: 
   The development of CIGS cells “might be slightly 
    constrained by shortages of gallium and 
    selenium,” while, mass production of CdTe 
    cells may be hampered by tellurium 
    availability (Lynn, 208, 2010).
   Generic Manufacturing of Silicon Panels:
  • Starting point for a polycrystalline cell is in molten form, 
   “cast in substantial blocks,” and then cut down to smaller 
   bricks and eventually into a thin wafer (Lynn, 2010).
  • “As the molten silicon cools, crystallization occurs 
   simultaneously,” and these cells are soldered to a diode that 
   conducts electricity (Lynn, 2010).
  • For a helpfully illustrative video on how a generic silicon cell 
   is produced click on the following link:
  • Discovery Channel: Solar Panel Manufacturing