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