The Solar
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SOLAR ENERGY The development of renewable energy has been an increasingly critical topic, due to the tremendous growth in energy demand that is expected to climb 35% by 2030 in comparison with current energy consumption. As a result of that an enormous pressure on existing conventional energy resources, in particular, fossil fuels such as oil and natural gas. Where they are currently providing more than 98% of the energy consumed worldwide. Dependence on fossil fuels presents a number of challenges, including: high cost, environmental damage, and lack of sustainability. Thus, looking for sustainable energy is a vital priority to address the world’s energy, environmental and economic challenges. One way to maintain sustainability is to rely on Renewable Energy sources. The most obvious source of renewable energy is the solar energy, therefore, a huge number of projects and researches have been adopted worldwide to utilize the indispensable sunlight as a sustainable source of energy. A typical solar energy system uses a photovoltaic (PV) solar panel or PV cell to convert the incident sunlight to electrical energy. The density of power radiated from the sun at the outer atmosphere is 1.373kW/m 2 . Part of this energy is absorbed and scattered by the earth’s atmosphere. The final incident sunlight on earth’s surface has a peak density of 1kW/m2 at noon in the tropics. The technology of PV is essentially concerned with the conversion of this energy into usable electrical form. The basic element of a PV system is the solar cell. Solar cells can convert the energy of sunlight directly into electricity. Consumer appliances used to provide services such as lighting, water pumping, refrigeration, telecommunications, and television can be run from photovoltaic electricity. Solar cells rely on a quantum-mechanical process known as the ‘‘photovoltaic effect’’ to produce electricity. A typical solar cell consists of a p-n junction formed in a semiconductor material similar to a diode. Fig.1 shows a schematic diagram of the cross section through a crystalline solar cell. It consists of a 0.2–0.3mm thick monocrystalline or polycrystalline silicon wafer having two layers with different electrical properties formed by ‘‘doping’’ it with other impurities (e.g., boron and phosphorus). An electric field is established at the junction between the negatively doped (using phosphorus atoms) and the positively doped (using boron atoms) silicon layers. If light is incident on the solar cell, the energy from the light (photons) creates free charge carriers, which are separated by the electrical field. An electrical voltage is generated at the external contacts, so that current can flow when a load is connected. The photocurrent (Iph), which is internally generated in the solar cell, is proportional to the radiation intensity.
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the solar energy
Transcript of The Solar
SOLAR ENERGY The development of renewable energy has been an increasingly critical topic d!e to the tremendo!s growth in energy demand that is e"pected to climb #$% by &'#' in comparison with c!rrent energy cons!mption( As a res!lt of that an enormo!s press!re on e"isting conventional energy reso!rces in partic!lar fossil f!els s!ch as oil and nat!ral gas( )here they are c!rrently providing more than *+% of the energy cons!med worldwide( ,ependence on fossil f!els presents a n!mber of challenges incl!ding- high cost environmental damage and lac. of s!stainability( Th!s loo.ing for s!stainable energy is a vital priority to address the world/s energy environmental and economic challenges( One way to maintain s!stainability is to rely on Renewable Energy so!rces( The most obvio!s so!rce of renewable energy is the solar energy therefore a h!ge n!mber of pro0ects and researches have been adopted worldwide to !tili1e the indispensables!nlight as a s!stainable so!rce of energy( A typical solar energy system !ses a photovoltaic2345 solar panel or 34 cell to convert the incident s!nlight to electrical energy(The density of power radiated from the s!n at the o!ter atmosphere is 6(#7#.)8m&( 3art of this energy is absorbed and scattered by the earth/s atmosphere( The 9nal incident s!nlight on earth/s s!rface has a pea. density of 6.)8m& at noon in the tropics( The technology of 34is essentially concerned with the conversion of this energy into !sable electrical form( The basic element of a 34 system is the solar cell( Solar cells can convert theenergy of s!nlight directly into electricity( :ons!mer appliances !sed to provide services s!ch as lighting water p!mping refrigeration telecomm!nications and television can be r!n from photovoltaic electricity( Solar cells rely on a ;!ant!mect// to prod!ce electricity( A typical solar cell consists of a perent electrical properties formed by ==doping// it withother imp!rities2e(g( boron and phosphor!s5( An electric 9eld is established at the 0!nction between the negatively doped 2!sing phosphor!s atoms5 and the positively doped 2!sing boron atoms5 silicon layers( @f light is incident on the solar cell the energy from the light 2photons5 creates free charge carriers which are separated by the electrical 9eld( An electrical voltage is generated at the e"ternal contacts so that c!rrent can Bow when a load is connected( The photoc!rrent 2@ph5 which is internally generated in the solar cell is proportional to the radiation intensity( ?ig(6-cross sectional view of solar cell ?ig(&-@4 and 34 c!rves of solar cell A simpli9ed e;!ivalent circ!it of a solar cell consists of a c!rrent so!rce in parallel with a diode( A variable resistor is connected to the solar cell generator as a load( )hen the terminals are short
