SOLAR ENERGY
Learning Objective
This module explains you how solar energy is useful to us and converting solar energy into electricity using solar cells.
Introduction/Overview
Solar energy is a completely renewable energy source derived from the energy derived from the radiations of the sun. this energy can be used for heating, generating electricity and drying of agricultural crops. Solar energy is necessary for maintaining life sustaining processes in trees and plants for processes such as photosynthesis. Without this energy many of the life processes will not take place which will prove devastating to the planet. Due to this important part it plays as an alternative source of energy, solar energy has been of great interest to our society.
There is more than adequate amount of energy from solar radiation reaching the earth for the world’s energy needs. The amount of solar energy that strikes Earth's surface per year is about 29,000 times greater than all of the energy used in the United States. Although the amount of solar energy reaching Earth's surface is immense, it is spread out over a large area. There are also limits to how efficiently it can be collected and converted into electricity and stored. The amount of solar energy recieved varies with the time of the day,Season weather and geographic location.
Solar energy is used for many application:
1)Photosynthesis
2)Heat (hot water,building heating,cooking)
3)Electricity Generation
Terminology:
PhotoVoltaics (PV) are solar cells or solar photovoltaic arrays that convert light from the sun into electricity, directly.
ATP:During Photosynthesis the energy derived from the light reaction is stored in a chemical form , ATP (adenosine triphosphate) , plant cells use this compound for energy storage.
Irradiance: Some of the radiometry terms used for expressing the power of electromagnetic radiation at a surface, per unit area are irradiance, radiant emittance, and radiant existence. “Irradiance is used when the electromagnetic radiation is incident on the surface. The other two terms are used for radiation emerging from the surface. These quantitites are expressed in SI system by watts per square meter ( W / m2 ).
Diode:Diode is an electronic device that restricts the directional flow of charge carriers. Simply speaking , a diode allows the passage of current in one direction whereas it blocks the carrier flow in the opposite direction.
Watt: One watt is one joule (the SI unit of energy) per second, that is 1 newton metre per second. It may be visualized simply as the amount of energy expended by a single candle.
In electrical terms, it follows that
1W =1V.1A
That is, if 1 volt of potential difference is applied to a resistive load, and a current of 1 ampere flows, then 1 watt of power is dissipated.