How solar panels are made

Solar Panels: From Sand to Silicon

In simple terms, here’s how solar, or photovoltaic, panels are made:

• The first step is to refine sand into pure silicon by removing the oxygen. This is done by heating it with carbon to over 3,600° F.
• The refined silicon is placed in a cylindrical furnace with a tiny amount of boron and heated again, this time to 2,500° F.
• Once melted, a seed crystal is introduced and drawn up through the top of the furnace. As the silicon cools, it forms a cylindrical crystal. The added boron ensures that the crystal has a positive potential electrical charge.
• The resulting crystal is cut into 2-foot ingots and squared. The ingots are then sliced into thin silicon crystal wafers.  These will become the panel’s solar cells. The square shape with rounded corners ensures maximum surface coverage with minimum waste from the cylindrical crystals.
• Before the wafers can produce electricity, they must undergo several additional steps. These include:
  • Texturing, to improve light absorption
  • Diffusing a thin layer of phosphorus onto the surface, which establishes a layer of negative potential electrical orientation (Remember the addition of boron earlier to give the wafer a potential positive orientation? The opposing electrical potentials will enable formation of an electrical current in the finished cell.)
  • Adding a silicon nitride coating to reduce reflection and further maximize light absorption
  • Printing of circuitry on both sides of the cell, to enable the collection and flow of electricity.
• Finally, the wafers are assembled into panels. They must be strung together to function as a unit, laminated onto a special type of solar glass, and set into lightweight aluminum framing to protect the assembly from weather and impacts.