Solar Energy

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In these days people are trying to find new energy sources. Because present energy sources are running down. So, alternative energy is so popular in these days. Because it has no danger to human life like nuclear powerplants, it is free to use and it has no waste. There are three types of alternative energy sources: Solar, wind and water. This report will be about solar energy. Its purpose is giving some information about solar energy to mechanical engineering students and engineers and calling attention on solar energy. The tree parts of this report discuss the history and operation of solar energy systems, the usage areas and advantages and disadvantages of using solar energy. The section on history and operation will discuss about history and operatio of solar system. The section on usage areas will mention about usage areas, like solar cars. The section on advantages and disadvantages will compare advantages and disadvantages to using solar energy. The final section will review the various costs involved in the using solar energy.

Development and Operation
Solar energy is the radiant energy which sun produced. Sun radiates a huge energy everyday. Using it is up to us. History of Solar Energy
People have been using solar energy by different ways for centuries. As early as the 7th century B.C., people were using glasses to concentrate the sunlight into the beams so hot. This beams were causing wood to catch fire. [pic]

Figure 1. Concentrating the Sunlight
Note. Renewable Energy Fair.(n.d.). history1. Retrieved February 02, 2009 from World Wide Web:

More than a century ago, a scientist used another method to use solar energy. He built a solar collector. And used its heat to produce steam. By this way he succesed to drive a steam engine. This invention inspired other scientist and engineers. So in the beginning of last century, researchs about solar energy increased in 1936 on American astrophysicist Charles Greeley Abbott invented a solar boiler. This was the one important development which has a remarkably efficent. In Florida, California and the Southwest the solar water heater become popular at this time . The industry started in 1920’s and reached the top just before World War II. In 1950’s when low-cost natural gas become popular this growth stopped. The public and world goverments remained the large possibilities at 1970’s because of oil shortages. Today people are using solar energy to heat buildings and water, generate electricity and even cars. Working Principle of Solar Systems

Sun radiates an enormous amount of energy. It is so huge that in one second sun radiates energy more than people have used since beginning(89pw). This energy comes from sun itself. Sun is full of gasses- mostly hydrogen and helium atoms- like the other stars. Sun produces nuclear fusion which is combination of helium and hydrogen atoms. We convert this energy with photovoltaic cells. Photovoltaic Cell: It works in steps the following:

Step 1: Pure silicon is used to form very thin wafers. A small amount of phosphorous added in half of the wafers (n-layer). In the other wafers, a small amount of boron is added (p-layer). The phosphorous gives the wafer of silicon an excess of free electrons; so it gains a negative character. N-layer is not charged but some electrons are not tightly held to atoms. In this wafer they are free to move the different locations. P-layer has a positive character but not a positive charge because of boron. Boron has tendency to attract electrons, so it has positive character but layer has equal protons and electrons. That’s why it is not positive charged. Step 2: When we place two wafers together, free electrons in n-layer are attracted to the p-layer. Free electrons from n-layer flow into p-layer for a split second, then form a...
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