What are Solar Cells
Solar cells are devices which convert solar light energy directly into electricity and function by the photovoltaic effect. Photo- means light and -voltaic means electrical current or electricity (light-electricity). A solar cell provides direct current (DC) electricity that can be used to power DC motors and light bulbs among other things. Solar cells can even be used to charge rechargeable batteries so that electricity can be stored for later use when the sun is not available. The fully charged batteries are portable energy that can be used whenever and wherever they are needed.
Solar cells provide DC electricity similar to batteries however, batteries differ because they operate through a process known as an electrochemical reaction. This process will provide an electrical current (electro-) from a chemical reaction (-chemical) that occurs inside the battery. When you hook up a motor to the battery, also known as a load, the reaction begins and electrons flow as shown in the picture: "Battery Circuit". Direct current (DC electricity) is different from the alternating current (AC electricity) that is used to power the TV, refrigerator, and other appliances in your home however, DC can be converted to AC when needed.
Battery Circuit
Solar cells produce DC electricity from light. Sunlight contains packets of energy called photons that can be converted directly into electrical energy. You can’t see the photons but they hit the cell and produce free electrons that move through the wires and cause an electrical current as shown in the picture: "Solar Cell Circuit". The electrical current is the electricity that powers the motor. Although you can't see the photons you can see the light and you can assume that the amount of photons hitting your solar cell is related to the amount of light hitting your solar cell. A greater amount of light available means a greater amount of photons are hitting your solar cell and the more power you get from it.
Solar Cell Circuit
Additional Reading:
Solar Cells Word Search Puzzle (PDF)
Presentation about Thomas Edison and the difference between AC and DC electrical current (WGBH).