Basics of energy conversion and solar cell working
- 1. Basics of Energy Conversion & Solar Cell Working Prepared By Miss. More Madhuri Mohan Ph. D Scholar Dept. of REE CTAE, MPUAT, Udaipur
- 2. Energy is all around you! You can hear energy You can see energy you can feel it
- 3. ENERGY is… the ability to do WORK or cause change WORK is… when a FORCE moves an object a FORCE is… a push or a pull
- 4. There are two main kinds of energy… POTENTIAL ENERGY STORED energy or Energy that is NOT being used KINETIC ENERGY Energy that IS being used or Energy in MOTION Examples: Examples:
- 5. Mechanical energy The sum of kinetic and potential energy in an object that is used to do work. Chemical Energy The energy stored in the bonds of chemical compounds (atoms and molecules). examples : Batteries, biomass, petroleum, natural gas, and coal. Radiant energy The energy of electromagnetic and gravitational radiation. The SI unit of radiant energy is the joule (J)
- 6. DIFFERENT FORMS OF ENERGY ELECTRICAL ENERGY Moving electrical charges ELECTROMAGNETIC ENERGY Light energy, X-rays, radio waves NUCLEAR ENERGY Stored in the nucleus of an atom & released when atoms are split or joined together, nuclear reactors, atomic bombs, stars, sun
- 7. A change from one form of energy to another is called energy conversion. Most forms of energy can be converted into any other form. Examples : a) Toaster converts electrical energy to thermal energy. b) Your body converts chemical energy in the food you eat into the mechanical energy you need to move your muscles. Heat energy is also formed in an energy conversion. Energy Transformations Conversions Between Forms of Energy Electrical Energy into Thermal Energy Chemical Energy into Mechanical Energy
- 8. Law of Conservation of Energy When one form of energy is converted to another, no energy is destroyed in the process. Energy cannot be created or destroyed, so the total amount of energy is the same before and after any process. All energy is accounted for. In 1905, Albert Einstein said that mass and energy can be converted into each other. He showed that if matter is destroyed, energy is created, and if energy is destroyed mass is created. E= 𝑚𝑐2 Where, E is Energy, m is unit Mass & c is Speed of light squared
- 9. source + import = export + variation of stock + use + loss Consider a primary energy balance. Sources are the local (or national) primary energy sources, like coal, hydro, biomass, animate, etc. Imports are energy sources which come from outside the region (or country). Exports go to other regions (or countries). Variations of stock are reductions of stocks (like of forests, coal, etc.), and storage. Use can be specified sectoral, or by energy form, or by end-use, etc., as required. Losses are technical losses and administrative losses: 1. Technical losses are due to conversions and transport or transmission 2. Administrative losses are due to non-registered consumptions. Energy Balance
- 10. How much heat is produced by a human body? A man doing no or very little physical work needs about 2,000 kcal (or less) of energy in his daily food. The body converts this energy almost entirely into heat. 1 day = 24 x 60 x 60 s = 86,400 s 1 cal = 4.2 J Hence We see that a human body doing no work is equivalent to a heat source of about 100 W - the equivalent of a good bulb. Examples of calculations of energy conversions
- 11. ENERGY SOURCES Biomass Biogas (Dung and animate) Hydro Resource Wind Energy Fossil Fuels Geothermal Energy Solar Radiation
- 12. Electricity from the sun
- 13. Energy from the Sun • About half the incoming solar energy reaches the Earth's surface. • The Earth receives 174 peta watts (PW) (1015 watts) of incoming solar radiation at the upper atmosphere. Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. • Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 °C. • By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.
- 14. • The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 3,850,000 exa joules (EJ) (1018 joules) per year. (70% of incoming sunlight) • Photosynthesis captures approximately 3,000 EJ per year in biomass. • The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth's non- renewable resources of coal, oil, natural gas, and mined uranium combined.
- 15. Breakdown of incoming solar energy
- 16. Solar Cells Background • 1839 - French physicist A. E. Becquerel first recognized the photovoltaic effect. • Photo+voltaic = convert light to electricity • 1883 - first solar cell built, by Charles Fritts, coated semiconductor selenium with an extremely thin layer of gold to form the junctions. • 1954 - Bell Laboratories, experimenting with semiconductors, accidentally found that silicon doped with certain impurities was very sensitive to light. Daryl Chapin, Calvin Fuller and Gerald Pearson, invented the first practical device for converting sunlight into useful electrical power. Resulted in the production of the first practical solar cells with a sunlight energy conversion efficiency of around 6%. • 1958 - First spacecraft to use solar panels was US satellite Vanguard 1
- 17. SEMICONDUCTOR • A material whose electrical conductivity is intermediate between that of an insulator and a conductor, behaves as an insulator at very low temperature. • It has appreciable electricity conductivity at room temperature lower than a conductor. • Commonly used semiconducting materials are Hydrogenated Silicon(a-Si/H), Germanium(G), Cadmium Telluride (Cd/Te), Cadmium Indium Gallium Selenide (CIGS), Gallium Arsenide(G/As), Indium Phosphate(In/P).
- 18. TYPES OF SEMICONDUCTORS • INTRINSIC SEMICONDUCTOR :- The conduction of a current in a semiconductor is only due to the electron excited from the valence band to the conduction band. • EXTRINSIC SEMICONDUCTORS :- The conduction of a current in a semiconductor is due to impurities. • DOPING :- The process of intentionally introducing impurities into an extremely pure semiconductor in order to change its electrical properties is called as doping. • DOPANTS :- The impurities that are added are called dopants.
- 19. How Solar Cells Work 1. Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon. 2. Electrons (negatively charged) are knocked loose from their atoms, allowing them to flow through the material to produce electricity. 3. An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.
- 20. Photo Voltaic cell Electrode P-Type Semiconductor N-Type Semiconductor Reflect-Proof Film Electrode Solar Energy Load ElectricCurrent Mechanism of generation The solar cell is composed of a P-type semiconductor and an N-type semiconductor. Solar light hitting the cell produces two types of electrons, negatively and positively charged electrons in the semiconductors. Negatively charged (-) electrons gather around the N-type semiconductor while positively charged (+) electrons gather around the P-type semiconductor. When you connect loads such as a light bulb, electric current flows between the two electrodes.
- 21. Direction of current inside PV cell P N Current appears to be in the reverse direction ? • Inside current of PV cell looks like “Reverse direction.” ? • By Solar Energy, current is pumped up from N-pole to P-pole. • In generation, current appears reverse. It is the same as for battery. P N Looks like reverse
- 23. Crystalline Non-crystalline Single crystal Poly crystalline Amorphous Gallium Arsenide (GaAs) Conversion Efficiency of Module 10 - 17% 10 - 13% 7 - 10% 18 - 30% Conversion Efficiency = Electric Energy Output Energy of Insolation on cell x 100% Dye-sensitized Type Organic Thin Layer Type 7 - 8% 2 - 3% Various type of PV cell • Types and Conversion Efficiency of Solar Cell Silicon Semiconductor Compound Semiconductor Solar Cell Organic Semiconductor
- 24. Where, Isc - Light generated current Imp - Current at maximum power point Vmp - Voltage at maximum power point Voc - Open circuit voltage Vmp Imp