| Light (particularly sunlight) can be used to | | | | Photovoltaic means, "creating electrical |
| create heat or generate electrical power. | | | | energy when exposed to light." |
| This is referred to as solar energy. | | | | |
| | | | A "cell" is a device that produces |
| It is a clean form of energy production, | | | | electricity. An example of an electrical cell |
| which doesn't pollute the environment as some | | | | is a flashlight battery. |
| other forms of energy production do. | | | | |
| | | | Photovoltaic cells produce electricity when |
| There are two forms of solar energy. The | | | | they are exposed to light. They usually |
| first is solar thermal conversion, which uses | | | | consist of panels. The panels contain two |
| sunlight to create heat and then electrical | | | | layers of different materials. |
| power. The second is photovoltaic conversion, | | | | |
| which uses sheets of special materials to | | | | When light hits these two layers, one of the |
| create electricity from the sun. "Photo-" | | | | layers becomes positively charged, and the |
| means "light," and "voltaic" means "producing | | | | other becomes negatively charged. |
| electricity." | | | | |
| | | | This works similarly to a regular flashlight |
| Solar Thermal Conversion | | | | battery, which has a positive end and a |
| | | | negative end. When a wire connects the two |
| Solar thermal conversion systems use | | | | ends, they produce an electric current. |
| reflectors or mirrors to concentrate sunlight | | | | |
| to extremely intense levels of heat. (Solar | | | | When the two layers of material in a solar |
| means "of the sun," thermal means "of heat" | | | | cell are exposed to light, they create an |
| and conversion means "changing something from | | | | electric current. |
| one form to another.") | | | | |
| | | | The AMOUNT of electricity generated by a |
| You can understand this better if you | | | | solar power cell depends on several factors. |
| consider the example of using a magnifying | | | | Mainly: |
| glass to start a fire. You may have heard of | | | | |
| this or even tried it before. You can hold a | | | | -How big is the solar power device, and how |
| magnifying glass under the sun, and | | | | much surface is exposed to the sun? |
| concentrate the light on a small pile of | | | | |
| flammable materials. The magnifying glass | | | | -How strong is the sun? (This depends on time |
| will make the sun's heat much stronger, and | | | | of day, weather, latitude, etc.) |
| will light the materials on fire. It has been | | | | |
| said that a magnifying glass one meter in | | | | -How long is the solar power device exposed? |
| diameter, held under the sun, will create a | | | | |
| ray hot enough to melt stone. | | | | -How much impediment is there to the light? |
| | | | (Clouds, mist, dust, dirt, etc.) |
| If you want to experiment, hold a magnifying | | | | |
| glass flat under the sun and put your hand | | | | In other words, a solar power cell generates |
| under it. Very soon you will need to move | | | | electricity faster when the sun (or light) is |
| your hand away - don't burn yourself. | | | | brighter. A device with larger solar panels |
| | | | will produce more electricity than one with |
| Solar thermal conversion systems use mirrors | | | | smaller panels. Exposing the cell for a |
| or reflectors to concentrate sunlight onto | | | | longer period of time will create more |
| containers full of liquid. Sometimes water is | | | | electricity than exposing it for a shorter |
| used. Sometimes other liquids are used, which | | | | period of time. A panel near the equator will |
| retain heat better than water. | | | | be more effective than one in an arctic |
| | | | region. A solar panel in misty or dusty |
| The liquids are heated up to high | | | | conditions does not create as much |
| temperatures, and this produces steam. The | | | | electricity as it would in full, unobstructed |
| steam is used to turn a turbine. The turning | | | | sun. |
| motion of the turbine is used to create | | | | |
| electricity. | | | | Some solar cells produce only enough current |
| | | | to power small electronic devices, but can be |
| How does a rotating motion create | | | | "daisy-chained" (connected together) in order |
| electricity? When you set up a coiled wire or | | | | to create more electricity for other items. |
| similar device to rotate between two magnets, | | | | |
| it generates an electric current. This is how | | | | Solar cells which produce enough electricity |
| electric generators work, as well as | | | | to run larger equipment (such as laptops) may |
| windmills, nuclear power plants, and other | | | | be larger, more expensive, or heavier than |
| energy plants which use such things as coal, | | | | the others. |
| gas, or petroleum. | | | | |
| | | | But there are many varieties available. |
| Windmills use the wind to create the turning | | | | Individuals and companies are consistently |
| motion. Nuclear power or fossil fuels are | | | | striving to create lighter and more efficient |
| used to heat water up, thus creating steam to | | | | portable solar cells. |
| turn the turbines. | | | | |
| | | | Solar Energy and the Future |
| Solar heating is another form of solar | | | | |
| thermal conversion. In solar heating, an | | | | An advantage to solar power is that it can |
| absorber is used to take in sunlight and | | | | reduce expenses. It can also be portable. |
| convert it to heat. The absorber could be | | | | When one is backpacking in the wilderness or |
| something simple, like black paint, or it | | | | traveling far from power grids, solar power |
| could be a special ceramic material. A heat | | | | can provide a means of powering electronic |
| absorber is considered to a be good one when | | | | equipment. |
| it collects at least 95 percent of the sun's | | | | |
| radiation. | | | | Another advantage is, of course, the lack of |
| | | | pollution created by solar energy production. |
| The absorbers are then used to heat a fluid, | | | | In fact, if all of our electrical energy were |
| which is then circulated to warm up buildings | | | | produced by such means, we might not be |
| or to create hot-water supplies. | | | | worrying about global warming and the other |
| | | | destructive effects of pollution on our |
| Photovoltaic Conversion | | | | environment. |
| | | | |
| As covered above, photo means "light." It | | | | These threats to our environment also pose a |
| comes from the Greek word "phos," which means | | | | threat to mankind. Solar power could be |
| "light." | | | | developed to a point where it, along with |
| | | | other forms of renewable energy, would |
| "Voltaic" means, "producing electric | | | | replace harmful means of electricity |
| current." The word comes from the name of | | | | production. |
| Alessandro Volta, an Italian physicist who | | | | |
| was a pioneer in the field of electricity | | | | It isn't necessarily impossible to have a |
| during the 1700's. (His name is also where | | | | clean and safe Earth. We just have to work on |
| the word "volt" comes from.) | | | | it. |
| | | | |