1. Guided by Mr. G.K. Pal DEPARTMENT OF MECH ENGG A SEMINAR REPORT Submitted by:- Subir Kumar Pramanik

3. CONTENTS Introduction. How much solar energy is useful? Photovoltaic system. Concentrating solar power plant. Solar panels in use. Advantage and disadvantage. Energy storage method. Efficiency. Final thought.

4. Introduction: The sun is the greatest and prime source of energy resulting from nuclear reaction within the plant mass. It radiates energy about 3.5×10^23kw into the space of which only 2×10^14kw comes to Earth. If a small % of this can be converted into useful power, this would solve the major energy crisis facing humanity.

5. What is Solar Energy? The sun radiates an enormous amount of energy called solar energy. Represents the entire electromagnetic radiation (visible light, infrared, ultraviolet, x-rays, and radio waves).

6. how much solar energy is useful? The surface receives about 47% of the total solar energy that reaches the Earth. Only this amount is usable.

7. Types of producing electricity from solar energy: SOLAR POWER is the generation of electricity from sunlight. This can be direct as with PHOTOVOLTAIES(PV) or indirect as with concentrating SOLAR POWER SYSTEM(CPS). SOLAR POWER is form of electromagnetic radiation emitted from sun, but especially that the part of there energy that is converted into THERMAL energy on the earth.

8. PHOTOVOLTAIC SYSTEM: PHOTOVOLTAICS are arrays of cells containing a solar photovoltaics material that convert solar radiation into direct current electricity. Materials present used for photovoltaics include monocrystalline silicon, polycrystalline sillicon, cadmium telluride

9. PHOTOVOLTAIC CELL: Photovoltaic cells are capable of directly converting sunlight into electricity. A simple wafer of silicon with wires attached to the layers. Current is produced based on types of silicon (n- and p- types) used for the layers. Each cell=0.5 volts. Battery needed as storage No moving parts  do no wear out, but because they are exposed to the weather, their lifespan is about 20 years.

10. CONCENTRATING SOLAR POWER PLANT CONCETRATING SOLAR POWER Concentrating Solar Power (CSP) systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. The concentrated heat is then used as a heat source for a conventional power plant. A wide range of concentrating technologies exists; the most developed are the parabolic trough the concentrating linear fresnel reflector, the Stirling dish and the solar power tower. Various techniques are used to track the Sun and focus light. In all of these systems a working fluid is heated by the concentrated sunlight, and is then used for power generation or energy storageworking fluid

12. Solar Panels in Use: Because of their current costs, only rural and other customers far away from power lines use solar panels because it is more cost effective than extending power lines. Note that utility companies are already purchasing, installing, and maintaining PV-home systems (Idaho Power Co.). Largest solar plant in US, sponsored by the DOE, served the Sacramento area, producing 2195 MWh of electric energy, making it cost competitive with fossil fuel plants.

13. Heating Living Spaces A passively heated home uses about 60-75% of the solar energy that hits its walls and windows. The Center for Renewable Resources estimates that in almost any climate, a well-designed passive solar home can reduce energy bills by 75% with an added construction cost of only 5-10%. About 25% of energy is used for water and space heating. Major factor discouraging solar heating is low energy prices.

14. Heating Living Spaces Passive Solar Trombe Wall Passively heated home in Colorado

15. Advantages and Disadvantages Advantages All chemical and radioactive polluting byproducts of the thermonuclear reactions remain behind on the sun, while only pure radiant energy reaches the Earth. Energy reaching the earth is incredible. By one calculation, 30 days of sunshine striking the Earth have the energy equivalent of the total of all the planet’s fossil fuels, both used and unused! Disadvantages Sun does not shine consistently. Solar energy is a diffuse source. To harness it, we must concentrate it into an amount and form that we can use, such as heat and electricity. Addressed by approaching the problem through: 1) collection, 2) conversion, 3) storage.

16. Energy storage method: Solar energy is not available at night, and energy storage is an important issue because modern energy systems usually assume continuous availability of energy. Solar energy can be stored at high temperatures using molten salts. Salts are an effective storage medium because they are low-cost, have a high specific heat capacity and can deliver heat at temperatures compatible with conventional power systems.molten salts

17. Efficiency Efficiency is far lass than the 77% of solar spectrum with usable wavelengths. 43% of photon energy is used to warm the crystal. Efficiency drops as temperature increases (from 24% at 0°C to 14% at 100°C.) Light is reflected off the front face and internal electrical resistance are other factors. Overall, the efficiency is about 10-14%.

18. Final Thought Argument that sun provides power only during the day is countered by the fact that 70% of energy demand is during daytime hours. At night, traditional methods can be used to generate the electricity. Goal is to decrease our dependence on fossil fuels. Currently, 75% of our electrical power is generated by coal-burning and nuclear power plants. Mitigates the effects of acid rain, carbon dioxide, and other impacts of burning coal and counters risks associated with nuclear energy. pollution free, indefinitely sustainable.

19. Thank You