How to Build a Simple Solar Cell

Building your own simple solar cell is a great way to introduce children to the concept of solar power. The solar cell described below produces enough energy, about .25 volts or 12.5 micro watts, to power a small radio. The key to this solar cell is the Cuprous Oxide which acts as a semi-conductor. Sunlight hitting the Cuprous Oxide provides electrons with enough energy to leave their atom. Free electrons conduct electricity through the saltwater to the other copper piece.

Things You'll Need

• Mild soap or detergent
• 2 6-by-6 inch pieces of copper flashing
• Wire brush or sandpaper
• Soft lint-free cloth
• Electric Burner
• Safety goggles
• 2 liter plastic bottle with the top 3 inches cut off or a wide mouth glass jar
• 2 alligator clip leads
• Volt meter sensitive enough to read currants between 10 and 50 micro amperes.
• 2 tbsp. of salt
• 2 cups of hot tap water

Instructions

1. Wash hyour ands thoroughly with mild soap or detergent to remove all traces of oil or grease.

2. Wash one of the copper pieces thoroughly with mild soap or detergent using a wire brush or sandpaper to remove all traces of oil and grease.

3. Thoroughly dry the copper piece with the soft lint-free cloth.

4. Wearing your safety goggles, place the cleaned and dried copper piece on the electric burner set on its highest setting for approximately thirty minutes or until a thick black coating called Cupric Oxide forms on both sides of the copper.

5. Turn off burner and allow the copper piece to cool on the burner. The copper should reach room temperature in about 20 minutes. As the copper cools it shrinks this causes the black layer of Cupric Oxide to flake off exposing the red Cuprous Oxide underneath.

6. Place the cooled piece of copper under running water. Use your fingers to gently remove the rest of the black Cupric Oxide.

7. Arrange both copper pieces inside the bottle so they are flat against the side of the bottle but are not touching.

8. Attach the alligator clips to the copper pieces, one clip for each piece, than attach the lead from the untouched piece of copper to the positive terminal of the meter and the lead from the piece of copper coated with the red Cuprous Oxide to the negative terminal of the meter.

9. Pour the salt into enough hot water (about 2 cups) to cover all but the top inch of the copper pieces, stir the salt until completely dissolved.

10. Pour the saltwater into the bottle.

Tips & Warnings

• The side that was facing up during the heating of the copper piece should face outwards, against the bottle, as it will be smoother than the side that was against the burner.

• Wear safety glasses while cooling the copper piece, the black Cupric Oxide may fly several feet as it flakes off the copper. If the copper cools too quickly the black Cupric Oxide will not come off. Be gentle while removing the Cupric Oxide so as to not damage the Cuprous oxide layer underneath. Do not get the alligator clips or leads wet while pouring the saltwater into the bottle.