Theme II: Developing Energy Resources The Miracle of Solar Cells KEEP Educator’s Activity Guide pgs KEEP Student Guide pgs NRES Energy Education in the Classroom Kristi Hawk April 4, 2008

The Miracle of Solar Cells 1. Background Info 2. Prompts 4. Anatomy of a PV Cell 5. Electricity 3. Investigate6. More Resources

The Miracle of Solar Cells Student Background Information Students should have a basic understanding of ~ the sun as our primary supplier of energy ~ energy conversions ~ the atom and the ability of electrons to move ~ energy uses and the need for electricity ~ the differences between non-renewable and renewable resources ~ basic electrical concepts such as current, conductivity, and open and closed circuits Menu

The Miracle of Solar Cells Student Prompts A solar cell is also known as a photovoltaic (PV) cell. What is the meaning for the prefix “photo”? What meaning do you derive from the base word “voltaic”? What or where are some homes or businesses which use solar panels? What items are you aware of which utilize solar cells? How is the childhood game of Red Rover, Red Rover played? How can this game be like the way a solar cell works? Menu

The Miracle of Solar Cells Investigation Materials: ~ Solar Cells ~ Motors and fan blades ~ Solar Cars Investigate: What do you observe about the PV cell? What possible significance would the dark color of the PV cell have? How can you make the motor spin? Or stop spinning? Menu

The Miracle of Solar Cells Anatomy of a Solar Cell PV cells have several layers of materials. Menu Most PV cells are made using Silicon. Atomic Structure of Si Silicon will bond with 4 other Si atoms. Silicon is “doped” by adding a few Phosphorus atoms. N (negative) layer of silicon is created. P (positive) layer does not contain free electrons (doped w/ Boron). Both sides are electrically neutral before solar energy is added.

The Miracle of Solar Cells How a PV Cell Makes Electricity Solar energy photons are absorbed by the non-reflective coating. This energy releases electrons from the N layer. Some P layer electrons are pushed through the junction to replace the vacated electrons’ spots. This current and voltage powers the electrical load. Solar disruption ends the flow of electrons. DC energy can be stored in batteries. It can also be converted to AC and sold back to the utility. Menu

The Miracle of Solar Cells More Resources We Energies Educator Renewable Energy Kit Discovery Channel’s MYTHBUSTERS – “Archimedes’ Death Ray” Large Scale Electrical Production Array in California Furnace in Odeillo, France Tower in Seville, Spain They Must Be Giants song “Why Does the Sun Shine?” : The Sun is a Mass of Incandescent Gas

The Miracle of Solar Cells They Might Be Giants – Why Does the Sun Shine? Lyrics The sun is a mass of incandescent gas A gigantic nuclear furnace Where hydrogen is built into helium At a temperature of millions of degrees The sun is hot, the sun is not a place where we could live But here on Earth there'd be no life Without the light it gives We need its light We need its heat The sunlight that we see The sunlight comes from our own sun's atomic energy The sun is a mass of incandescent gas A gigantic nuclear furnace Where hydrogen is built into helium At a temperature of millions of degrees The sun is hot- The sun is so hot that everything on it is a gas: aluminum, copper, iron, and many others. The sun is large - If the sun were hollow, a million Earths would fit inside. And yet, it is only a middle-sized star. The sun is far away - About 93 million miles away, and that's why it looks so small. But even when it's out of sight The sun shines night and day We need its heat We need its light The sunlight that we see The sunlight comes from our own sun's atomic energy Scientists have found that the sun is a huge atom-smashing machine. The heat and light of the sun are caused by nuclear reactions between hydrogen, nitrogen, carbon, and helium.* The sun is a mass of incandescent gas A gigantic nuclear furnace Where hydrogen is built into helium At a temperature of millions of degrees The End