Solar Energy

INTRODUCTION 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: http://www.renewableenergyfair.com/history.htm

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 barrier. This barrier prevents more electrons from moving between layers. This barrier is called the p-n junction. Once the layers joined, in p-layer section of the junction there is a negative charge and positive charge in the n-layer section of the junction. This imbalance in charge at the p-n junction produces and electric field between the p-layer and n-layer. Step 3: If we put this PV (photovoltaic) cell in the sun, photons (packets) of light strike the electrons in the p-n junction and energize them, knocking them free of their atoms. Those elecrtons are attrached to the positive charge in the n-layer and repelled by the negative charge in the p-layer. Step 4: When you attach a wire from n-layer to the p-layer, free electrons are pushed into the n-layer, they repel each other. Electrons get away from that path which provides by the wire. This flow of electrons is an electricity current. [pic]
Figure 2. Photovoltaic Cell. Note. Replete Energy (P) Ltd.(n.d.). Retrieved February 02, 2009 from World Wide Web: http://repleteenergy.com/p.v.info.html

USAGE AREAS OF SOLAR ENERGY
Daily Life Usage Human being have been using solar energy since humans have existed on the earth. There are multiple ways to use solar energy. We even don’t recognise have been using some of these ways in our daily life. For example, when we hang laundary outside to dry, solar energy is working by solar heating method. If we think details, plants are using solar light to make food. On other hand decaying plants million years ago produced some natural gasses, coal and oil that we are using today. But scientist and engineers are not contented with these simple methods and built more complicated systems that we use in our daily life now. These days solar energy become a part of our daily life. We can see different solar systems in sunny places. Its real reason is producing electricity from a clean, non-polluting, renewable source by paying a small premium. So people who are using PV system for electricity, don’t have monthly power bill. Because of these advantages people decided to use solar energy in all fields. So today we can see PV systems. For water pumping, lighting, heating at homes, schools and community halls. We can see solar energy in industrial applications which needs a few kilowatt of power like telemetry and radio telephones. Solar energy is also using increasly on transportation signalling like lighthouses, offshore navigation buoys and road traffic warning signals. Using solar energy that much was not enough for some people, so they produced batteries. These batteries loads the energy which PV panels produced on daylight hours. By this way people can use solar energy at nights also. [pic]
Figure 3. Battery System.
Note. CBS Energy.(n.d.). Retrieved February 03, 2009 from World Wide Web: http://www.cbsenergy.co.uk/solar.html

Solar Cars Solar cars are very ambitious goal for human being. Firstly it was only a dream, but then some people spent a lot of money and time and made this dream possible. Shih (1998) states that: “Solar cars are powered by sun’s energy. The solar cells collect a portion of the sun’s energy and stores it into the batteries of solar car” We can see the working principle at figure 4. [pic]
Figure 4. Solar Car Working Principle.
Note. Shih,W.(1998). Retrieved January 02, 2009 from World Wide Web: http://www.winstonsolar.org/info/intro.html Other Usage Areas Solar energy has been using on other areas also. Some of them are: • To tell time Our sense of time is marked by how and where we perceive the sun, as our tilted planet spins daily. Yearly our planet orbits the sun, and as a result of life 's reactions to the changes of received energy at any location we perceive the seasons. As the sun appears to be lower or higher in the horizion, and as Earth spins from West to East (so that the sun appears to moving from East to West) a stick 's shadow will clearly change length and position throughout each day and through the year. [pic]
Figure 5. Telling Time.
Note. SunWind Solar Industries, Inc.(2003.). Retrieved February 03, 2009 from World Wide Web: http://www.web.net/~sunwind/solar/solar_energy_uses.html

• To Cook Solar Cookers are an excellent way to study the gathering and using of direct solar energy. [pic]
Figure 6. Cooking with Solar Energy.
Note. SunWind Solar Industries, Inc.(2003.). Retrieved February 03, 2009 from World Wide Web: http://www.web.net/~sunwind/solar/solar_energy_uses.html

• To Purify Water Harmful bacteria in water can be killed by bringing the water 's temperature up to 65 degrees Celsius (150 degrees Fahrenheit) for a few minutes. It is not necessary to boil, though this is a good visual indicator that the water is more than hot enough. • To Explore Other Planets [pic]
Figure 7. Planet Explorer.
Note. SunWind Solar Industries, Inc.(2003.). Retrieved February 03, 2009 from World Wide Web: http://www.web.net/~sunwind/solar/solar_energy_uses.html

ADVANTAGES AND DISADVANTAGES OF SOLAR ENERGY Solar energy is one of the most promising alternative energy source. But it also have advantages and disadvantages.
Advantages of Solar Energy Solar energy is one of the newest and most cost effective way producing energy. It can satisfy the huge energy needs of humanbeings. Solar energy has useful applications in day life with many advantages. Solar energy is abundant, partically never run out. Solar energy can be provided from sunlight even in midwinter. So humanbeings use this energy all the time but it never run out. People use this energy also free. There is an initial capital cost as everything but solar photovoltaic technology is growing rapidly and it will reduce the payback time. No one will send you a bill for using sunshine, so in a few years after setting the system you will be in profit. Solar energy has countless benefits. One of them is cleanliness. While taking attention to global warming these days, solar energy points out itself. It has no waste, it doesn’t produce anything harmful, because it uses just sunlight. We can aline other benefits like this: • Solar energy is odour free, • Silent, • Long life system equipment
Finally; solar energy gives you independence. If you have a solar system you are not dependent on national sources and grid-connection. You don’t effect from terrorism, pandemic problems and climbing fuel prices. Acording to advantages of solar energy, Wright (2005) states “When we compare, electricity reduced solar heat air-conditioning and electricity produced solar energy, AC solar energy is more beneficial even without discounts.” (p.81-82) Solar energy gives you indepence even while champing as seen in Figure 8. [pic] Figure 8. Solar Power On a Van.
Note. Big Frog Mountain Corporation.(n.d.). Mobile Solar Power - even while camping. Retrieved January 13, 2009 from World Wide Web: http://www.bigfrogmountain.com/campers.cfm

Disadvantages of Solar Energy Solar energy also has some disadvantages like everything. Solar systems have 5 main disadvantages. Firstly the initial setup cost. If someone wants to setup a solar system he/she must has considerable money. Even have enough money there is the location disadvantage. Adequate access to shineshine for a good part of the day is another consideration. Few places on the earth exist where can’t have enough sunlight to least capacity. North-south position is also promblem for having reasonable sunlight. If you have enough money and enough sunlight, you have roofing consideration. Solar cells require quite large area. So roofing needs to be carefully considered before applying a solar array. Once a home solar system has been installed repairs and replacement to an existing roof can become expensive and labour intensive. When there is a major work to do on roof, the system must be removed an re-installed. If everything is OK so far you have night problem. At night there is no sun, if there is no sun, there is no sunlight, if there is no sunlight, there is no solar energy production. This problem is solved with batteries. Lead batteries are most common on this. But they also have some disadvantages. Lead has been found to be serious health risk to children and waste of a lead battery is dangerous for envoirment. The good news is that %98 of the materials in dead batteries are recoveable when recycled.Even we get over of all these disadvantages we have another problem. Maybe not now but after a few years the disposal of materials used to collect and store the energy once those materials have been retired can cause some problems. Because these days most solar cells are partially composed of cadmium and cadmium is highly toxic to the enviroment.

Comparing Advantages and Disadvantages of Solar Energy The disadvantages of solar energy are fast being eliminated with the constant threat of calamity, environmental issues looming and fossil fuel supplies under the control of volatile nations, the disadvantages may become negligible. If we compare advantages and disadvantages of solar energy,we can say there are many more advantages than disadvantages.

CONCLUSION In this report I have tried to give information about solar energy. I have explanied history of solar energy and how solar systems work. Then I talked about usage areas of solar energy. I mentioned about solar cars, PV systems and any other usage areas. Finally I made a comparison about advantages and disadvantages of solar energy. I think solar energy is an unvaluable energy source. Its being renewable and huge potential makes solar energy an indipenciple part for our causal life.

REFERENCES
Big Frog Mountain Corporation. (n.d.). Mobile Solar Power - even while camping. Retrived January 13, 2009 from World Wide Web:http://www.bigfrogmountain.com/campers.cfm
CBS Energy.(n.d.). Retrieved February 03, 2009 from World Wide Web: http://www.cbsenergy.co.uk/solar.html
Renewable Energy Fair.(n.d.). history1. Retrieved February 02, 2009 from World Wide Web: http://www.renewableenergyfair.com/history.htm
Replete Energy (P) Ltd.(n.d.). Retrieved February 02, 2009 from World Wide Web: http://repleteenergy.com/p.v.info.html
Shih,W. (1998). Retrieved January 02, 2009 from World Wide Web: http://www.winstonsolar.org/info/intro.html
Solar Energy Profits. (n.d.). Solar Energy Advantages Disadvantages Retrived January 13, 2009 from World Wide Web: http://www.solarenergyprofits.com/
Sun Products. (n.d.). Advantages of Solar Energy Retrived January 13, 2009 from World Wide Web: http://www.solarhome.org/infoadvantagesofsolarenergy.html
SunWind Solar Industries, Inc. (2003.). Retrieved February 03, 2009 from World Wide Web: http://www.web.net/~sunwind/solar/solar_energy_uses.html
University of Bristol. (n.d.) Adcantages of Solar Energy Retrived January 13, 2009 from World Wide Web: http://www.chm.bris.ac.uk/webprojects2003/ledlie/advantages_of_solar_energy.htm
Van Wyk, A. (2005, July 10). Solar Energy Advantages Disadvantages. Retrieved January 14, 2009, from http://ezinearticles.com/?Solar-Energy-Advantages-Disadvantages&id=50178
Wright, G.(2005). Technology of Solar Energy Cooling System with Solar Energy. The Journal of Engineering of System, 87, 80-82.

References: Big Frog Mountain Corporation. (n.d.). Mobile Solar Power - even while camping. Retrived January 13, 2009 from World Wide Web:http://www.bigfrogmountain.com/campers.cfm CBS Energy.(n.d.) Sun Products. (n.d.). Advantages of Solar Energy Retrived January 13, 2009 from World Wide Web: http://www.solarhome.org/infoadvantagesofsolarenergy.html SunWind Solar Industries, Inc Van Wyk, A. (2005, July 10). Solar Energy Advantages Disadvantages. Retrieved January 14, 2009, from http://ezinearticles.com/?Solar-Energy-Advantages-Disadvantages&id=50178 Wright, G.(2005)