ppt on photo voltaic effect

Q: What is photovoltaics (solar electricity) or "PV"?
A: What do we mean by photovoltaics? The word itself helps to explain how photovoltaic (PV) or solar
electric technologies work. First used in about 1890, the word has two parts: photo, a stem derived from
the Greek phos, which means light, and volt, a measurement unit named for Alessandro Volta
(1745-1827), a pioneer in the study of electricity. So, photovoltaics could literally be translated as
light-electricity. And that's just what photovoltaic materials and devices do; they convert light energy to
electricity, as Edmond Becquerel and others discovered in the 18th Century.
Q: How can we get electricity from the sun?
A: When certain semiconducting materials, such as certain kinds of silicon, are exposed to sunlight, they
release small amounts of electricity. This process is known as the photoelectric effect. The photoelectric
effect refers to the emission, or ejection, of electrons from the surface of a metal in response to light. It
is the basic physical process in which a solar electric or photovoltaic (PV) cell converts sunlight to
electricity.
Sunlight is made up of photons, or particles of solar energy. Photons contain various amounts of energy,
corresponding to the different wavelengths of the solar spectrum. When photons strike a PV cell, they
may be reflected or absorbed, or they may pass right through. Only the absorbed photons generate
electricity. When this happens, the energy of the photon is transferred to an electron in an atom of the
PV cell (which is actually a semiconductor).
With its newfound energy, the electron escapes from its normal position in an atom of the
semiconductor material and becomes part of the current in an electrical circuit. By leaving its position,
the electron causes a hole to form. Special electrical properties of the PV cell—a built-in electric
field—provide the voltage needed to drive the current through an external load (such as a light bulb).
Q: What are the components of a photovoltaic (PV) system?
A: A PV system is made up of different components. These include PV modules (groups of PV cells),
which are commonly called PV panels; one or more batteries; a charge regulator or controller for a
stand-alone system; an inverter for a utility-grid-connected system and when alternating current (ac)
rather than direct current (dc) is required; wiring; and mounting hardware or a framework.
Q: How long do photovoltaic (PV) systems last?
A: A PV system that is designed, installed, and maintained well will operate for more than 20 years. The
basic PV module (interconnected, enclosed panel of PV cells) has no moving parts and can last more than
30 years. The best way to ensure and extend the life and effectiveness of your PV system is by having it
installed and maintained properly. Experience has shown that most problems occur because of poor or
sloppy system installation.

1. Solid state deviceS Presented By- TOPIC : PHOTOVOLTAIC EFFECT ELECTRONICS AND TELECOMMUNICATION ENGINEERING SECOND YEAR 1. Arpita Banerjee 2. Rohan Hore 3. Soumya Ghosh Chowdhury 3. Ranik Ahamed

2. index DEFINATION OF PHOTOVOLTAIC EFFECT INVENTED BY DESCRIPTION HOW DO PHOTOVOLTAICS WORK? USES OF PHOTOVOLTAIC EFFECT HOW CAN WE GET ELECTRICITY FROM THE SUN? WHAT'S THE DIFFERENCE BETWEEN PV AND OTHER SOLAR ENERGY TECHNOLOGIES? WHY SHOULD WE PURCHASE A PV SYSTEM? ADVANTAGES DISADVANTAGES ENQUERIES ??? THANK YOU

3. The photovotaic effect can be defined as being the appearance of a potential difference (voltage) between two layers of a semiconductor slice in which the conductivities are opposite , or between a semiconductor and a metal, under the effect of a light stream. DEFINATION OF PHOTOVOLTAIC EFFECT

4. INVENTED BY- The photovoltaic effect was first discovered in 1839 by Edmond Becquerel.When doing experiments involving weight cells, he noted that the voltage of the cell increased when its silver plates where exposed to the sunlight.

5. When photons are absorbed by photo sensitizer a voltage difference across a junction is produced. The voltage difference is caused by the internal drift of electrons which accepted the light energy and leaved the normal position. Photovoltaic effect is the basic physical process through which a solar cell convert sunlight into electricity . DESCRIPTION

6. How do Photovoltaics Work? Top layer is made up of silicon and n type(phosphorous) doping. First layer become negative type due to excess of negative electrons. Middle layer has low margin of p type material.. The bottom layer is doped p type(boron) along with silicon.

7. USES OF PHOTOVOLTAIC EFFECT

8. How can we get electricity from the sun? When certain semiconducting materials, such as certain kinds of silicon, are exposed to sunlight, they release small amounts of electricity. This process is known as the photoelectric effect. The photoelectric effect refers to the emission, of electrons from the surface of a metal in response to light. It is the basic physical process in which a solar electric or photovoltaic (PV) cell converts sunlight to electricity . Sunlight is made up of photons, or particles of solar energy. Photons contain various amounts of energy, corresponding to the different wavelengths of the solar spectrum. When photons strike a PV cell, they may be reflected or absorbed, or they may pass right through. Only the absorbed photons generate electricity . When this happens , the energy of the photon is transferred to an electron in an atom of the PV cell (which is actually a semiconductor).

9. What's the difference between PV and other solar energy technologies? Photovoltaic (PV) systems, which convert sunlight directly to electricity by means of PV cells made of semiconductor materials. Concentrating solar power (CSP) systems, which concentrate the sun's energy using reflective devices such as troughs or mirror panels to produce heat that is then used to generate electricity. Solar water heating systems, which contain a solar collector that faces the sun and either heats water directly or heats a "working fluid" that, in turn, is used to heat water. Transpired solar collectors, or "solar walls," which use solar energy to preheat ventilation air for a building.

10. Why should WE purchase a PV system? People decide to buy solar products to preserve the Earth's finite fossil-fuel resources and to reduce air pollution . Others would rather spend their money on an energy-producing improvement to their property than send their money to a utility . Some people like the security of reducing the amount of electricity they buy from their utility . If it's designed correctly, a solar system might be able to provide power during a utility power outage , thereby adding power reliability to your home.

11. ADVANTAGES ELECTRICITY PRODUCED BY SOLAR CELLS IS CLEAN AND SILENT . PV SYSTEMS ARE QUIET AND VISUALLY UNOBTRUSIVE . SMALL- SCALE SOLAR PLANT S CAN TAKE ADVANTAGE OF UNUSED SPACE ON ROOF TOPS OF EXISTING BUILDINGS. SOLAR ENERGY IS A LOCALLY AVAILABLE RENEWABLE RESOURCE. IT DOESN`T NEED TO BE IMPORTED FROM OTHER REGIONS OF THE COUNTRY OR ACROSS THE WORLD.

12. DISADVANTAGES Some toxic chemicals, like Cadmium( Cd ) and Arsenic(A s), are used in the pv production process . Solar energy is somewhat more expensive to produce than conventional sources of energy due in part to the cost of manufacturing pv devices and in part to conversion efficiencies of the equipment. Solar power is a variable energy source, with energy production dependent on the sun .

13. ENQUERIES ??? WHAT IS PHOTOVOLTAICS ? WHAT ARE THE COMPONENTS OF PV SYSTEM ? CAN WE USE PHOTOVOLTAICS TO POWER OUR HOME ?

14. THANK YOU