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