Solar Energy solar energy Page Contents: Solar Energy Page 1» How Solar Energy is Formed and Used Page 2» Photosynthesis Page 3» History of Solar Energy (700 BC-1914) Page 4» History of Solar Energy (1916-present) Page 5» Solar Energy in Developing Countries Solar energy is the radiant energy (light or heat) that comes from the sun. Only a small amount of the sun’s energy strikes the Earth, one part per 2 million. But even that one part is an enormous amount of energy. Solar energy is the most abundant energy source available. In fact, according to National Geographic, every hour, the sun beams enough energy to meet the entire world’s energy needs for a year! The tricky part is harnessing the energy effectively to meet those needs. Solar power depends on the sun being out—and when it’s not, solar panels generate no power. However, storage systems can collect the sun’s energy to be used during cloudy weather or at night. Solar power systems, once they’re up and operational, last for 15-30 years. And while in 2008 solar only provided .02% of the world’s energy, that number is growing every year. How Solar Energy is Formed and Used Sunlight can be directly used to create electricity using solar, or photovoltaic (PV) cells. The solar cells are made using silicon, the same thing that makes up sand. Even though silicon is found almost everywhere, making a solar panel is a difficult and expensive process. According to a report in the New York Times, “generating power from photovoltaic panels costs more than four times as much as coal, and more than twice what wind power costs.” Polysilicon, a material made up of small silicon crystals that is used to make photovoltaic cells, is sometimes in short supply, which means prices for solar equipment can be volatile. The silicon is heated and melted at super high temperatures and then molded into thin wafers. When sunlight strikes the solar cell, electrons are loosened and move toward a treated front surface, making an imbalance between the front and back. Electricity occurs when a connector, such as a wire, joins the negative and positive sides together. The production of photovoltaic cells, which are used to change sunlight directly into electricity, causes far less pollution than fossil fuel-burning power plants. While manufacturing the cells does require harmful metals such as lead and mercury and also produces some greenhouse gases, the toxic emissions are up to 300 times lower than those created by coal power plants, according to scientists with the Brookhaven National Laboratory in New York.
Posted on: Sun, 14 Jul 2013 17:41:49 +0000
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