||The Ultimate Renewable Resource
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What is solar energy..?
Solar energy is radiant energy that is produced by the sun. Every day the sun radiates, or sends out, an enormous amount of energy. The sun radiates more energy in one second than people have used since the beginning of time!
Where does the energy come from that constantly radiate from the sun?
It comes from within the sun itself. Like other stars, the sun is a big ball of gases mostly hydrogen and helium atoms. The hydrogen atoms in the sun’s core combine to form helium and generate energy in a process called nuclear fusion.
During nuclear fusion, the sun’s extremely high pressure and temperature cause hydrogen atoms to come apart and their nuclei (the central cores of the atoms) to fuse or combine. Four hydrogen nuclei fuse to become one helium atom. But the helium atom contains less mass than the four hydrogen atoms that fused. Some matter is lost during nuclear fusion. The lost matter is emitted into space as Radiant Energy.
It takes millions of years for the energy in the sun’s core to make its way to the solar surface, and then just a little over eight minutes to travel the 93 million miles to earth. The solar energy travels to the earth at a speed of 186,000 miles per second, the speed of light. Only a small portion of the energy radiated by the sun into space strikes the earth, one part in two billion. Yet this amount of energy is enormous. Every day enough energy strikes the United States to supply the nation’s energy needs for one and a half years!
Where does all this energy go?
About 15 percent of the sun’s energy that hits the earth is reflected back into space. Another 30 percent is used to evaporate water, which, lifted into the atmosphere, produces rainfall. Solar energy also is absorbed by plants, the land, and the oceans. The rest could be used to supply our energy needs.
Concept of project
The unique feature of the system is that it is an online solar powered operating system. The project mainly consists of four sections namely a capacitor bank, a microcontroller, a solar panel and a load.
The main feature and also one of the greatest advantages of this system is that it does not use battery to supply power to the load; instead of battery it uses capacitor banks to supply the load. There are four different capacitor banks used in this system, where the banks are switched one by one using the high frequency switching through the microcontroller. The load will directly run on the solar energy, one capacitor is switched on to supply the load, when it discharges the other bank is switched on to supply the load, and this cycle is continued. The solar energy from the sun is converted into a dc supply by the photo-voltaic cells which indirectly supply the load.
Thus the load is supplied continuously without any interruption and therefore the goal of efficient, cheap and reliable use of energy is achieved.
People have harnessed solar energy for centuries. As early as in the 7th century B.C people used simple magnifying glasses to concentrate the light of the sun into beams, so hot they would cause wood to catch fire. More than 100 years ago in France a scientist used heat from a solar collector to make steam to drive a steam engine. In the beginning of this century scientists and engineers began researching ways to use solar energy in earnest. One important development was a remarkably efficient solar boiler invented by Charles Greeley Abbott an American astrophysicist in 1936.
The solar water heater gained popularity at this time in Florida, California and the Southwest. The industry started in the early 1920s and was in full swing just before World War II. This growth lasted until the mid 1950s when low-cost natural gas became the primary fuel for heating American homes. The public and world governments remained largely indifferent to the possibilities of solar energy until the oil shortages of the 1970s. Today people use solar energy to heat buildings and water and to generate electricity. To perform this study it was necessary to understand solar energy collection and its conversion into electricity evaluation of electrical performance and the current efforts being made to improve conversion efficiency. It was also important to examine the actual effect of the color filters on the light input into the panel. The primary material used in the modern collection of solar energy is silicon. Even though it takes 100 times more surface area of silicon than that of other solid-state materials to collect the same amount of energy silicon was already developed and in mass production when solar energy collection technology was developed and so it was the practical choice (Goetzberger, Luther, & Willeke, 2002). However any semiconductor is acceptable.
The semiconductor is part of a panel called a photovoltaic or solar cell. This cell absorbs sunlight and transfers it into electricity typically with 15-20% efficiency (Kribus, 2002). The true principle of this study (the factor observed) centers not on the inner processes involved in the energy transfer but rather on the efficiency of the solar cell. The purpose of solar panels and solar energy collection is for the output of power measured in Watts (P=V x I, V=voltage, I=current). However in order to study how factors affect this output it is crucial to understand how this performance is evaluated. A study was conducted by the Florida Solar Energy Center (1999) observing the performance of two separate solar setups for homes in Kissimmee, Florida. Analyses were done on the long-term performance and efficiency of the two systems measuring power over time in Watt-hours. This study examines similar parameters on a smaller scale but does not look at many of the extra angles examined by this study. For example, the standard requirements of Electrical Codes had to be considered, which does not apply in this study.
In essence, the Florida study was designed to incorporate all the elements necessary to practically supply a fully functional family home with all its electrical needs, whereas this study is more concerned with the general principles of solar energy collection. However, the most basic analyses are the same. The Florida study determined photovoltaic’s to be an adequate and acceptable alternative to standard electrical power. Kivalov, Salikhov, Tadzhiev, and Avezov’s study (2001) is another excellent look at evaluation of output. It examined thermal efficiency of solar panels a factor not being considered in this study but still present sound examples of useful graphics aptly demonstrated analysis equations and a good explanation of what it all means. A scatter plot with a linear regression was displayed and used to determine the thermal efficiency coefficient which was then compared to calculated values of the same. These are sound statistical techniques that can be applied to a variety of situations.
Efficiency is the ratio of total energy input into a machine or other system to the total energy output (e = useful energy output/energy input). Solar energy collection efficiency has improved as the general technology has improved growing from the first passive collection methods (efficiency approx. 1%) to the current applicable methods (efficiency approx. 15-20%) (Kribus, 2002). Studies have been done toward the next advance for increased output and efficiency. The issue has been examined from several angles both from that of maximum possible efficiency and from that of highest possible efficiency while remaining industrially feasible. Kribus’s study (2002) delivered an examination of a new process with efficiencies approaching 70% although it would be difficult and extremely expensive probably too much so to be economically feasible.
In the conversion within the panel from sunlight to electricity efficiency will rise if the panel can operate at higher temperatures. Normal panels use a double cycle conversion process; Kribus (2002 introduces a triple cycle the first of which operates at extremely high temperatures. It is called a magneto-hydro-dynamic (MHD) cycle and can operate at temperatures in the range of 2000° - 2500° up from the current limit of about 1300°). Hezel’s (2002) study presented a panel with increased efficiency possibly approaching 30% that is still feasible for mass production. His design uses a different kind of silicon called Czochralski silicon with oblique evaporated contacts (OECO). The contact points are metallized using low-cost aluminum and obliquely evaporated using a very simple four-step process that may prove to be feasible for mass production. These improvements being made in the technology are wonderful, but worthless unless they can be put to good use. Why should scientists bother with all the effort of improving alternative energy collection methods when the world is already quite happy with its current energy supply? Obviously fossil fuels will only last so long, and solar energy is emerging as the heir-apparent to the oil dynasty as the best choice economically and ecologically (Hamakawa, 2002). There are a number of emerging new applications as well.