Ncer Presentation on Photovoltaics

7/30/2019 Ncer Presentation on Photovoltaics

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Submitted by:

1.Ayush Anagh 100106098

2.Arvind Vikram Singh Kandari-100106078

3. Ashish Sharma-100106087

4.Abhijeet Anand Giri-1001060045.Ayan Chakravarty-100106097

Branch : Mechanical

Section: ME-A Term-05 3rd Year

PHOTOVOLTAICS


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Introduction Photovoltaics (PV) is a method of generating

electrical power by converting solar radiation intodirect current electricity using semiconductors thatexhibit the photovoltaic effect.

Photovoltaic power generation employs solar panelscomposed of a number of solar cells containing aphotovoltaic material.

Materials presently used for photovoltaics include

monocrystalline silicon, polycrystalline silicon,amorphous silicon, cadmium telluride, and copperindium gallium selenide/sulfide.

Due to the growing demand for renewable energy

sources, the manufacturing of solar cells andphotovoltaic arrays has advanced considerably in


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Solar Cells Photovoltaics are best known as a method for

generating electric power by using solar cells toconvert energy from the sun into a flow ofelectrons. The photovoltaic effect refers to

photons of light exciting electrons into a higherstate of energy, allowing them to act as chargecarriers for an electric current. The photovoltaiceffect was first observed by Alexandre-Edmond

Becquerel in 1839. The term photovoltaic denotes the unbiased

operating mode of a photodiode in which currentthrough the device is entirely due to the

transduced light energy. Virtually all photovoltaic


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The operation of a photovoltaic (PV) cell requires 3basic attributes:

1. The absorption of light, generating eitherelectron-hole pairs orexcitons.

2. The separation of charge carriers of opposite types.

3. The separate extraction of those carriers to an

external circuit. Assemblies of photovoltaic cells are used to make

solar modules which generate electrical power fromsunlight. Multiple cells in an integrated group, all

oriented in one plane, constitute a solar photovoltaicpanelor "solar photovoltaic module," as distinguishedfrom a "solar thermal module" or "solar hot waterpanel." The electrical energy generated from solarmodules, referred to as solar power, is an example ofsolar energy. A group of connected solar modules
http://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Electron_holehttp://en.wikipedia.org/wiki/Excitonshttp://en.wikipedia.org/wiki/Solar_modulehttp://en.wikipedia.org/wiki/Sunlighthttp://en.wikipedia.org/wiki/Solar_powerhttp://en.wikipedia.org/wiki/Solar_energyhttp://en.wikipedia.org/wiki/Solar_energyhttp://en.wikipedia.org/wiki/Solar_powerhttp://en.wikipedia.org/wiki/Sunlighthttp://en.wikipedia.org/wiki/Solar_modulehttp://en.wikipedia.org/wiki/Excitonshttp://en.wikipedia.org/wiki/Electron_holehttp://en.wikipedia.org/wiki/Electron


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The solar cell works in three steps:

1. Photons in sunlight hit the solar panel and are

absorbed by semiconducting materials, such assilicon.

2. Electrons (negatively charged) are knockedloose from their atoms, causing an electric

potential difference. Current starts flowingthrough the material to cancel the potential andthis electricity is captured. Due to the specialcomposition of solar cells, the electrons are onlyallowed to move in a single direction.

3. An array of solar cells converts solar energy intoa usable amount of direct current (DC)electricity.


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Applications of photovoltaics

Photovoltaics find their application in followingfields:

In buildings

In transport Standalone devices

Rural electrification

Solar roadways

Plug in solar


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1. PV in buildings Photovoltaic arrays are often

associated with buildings: eitherintegrated into them, mounted onthem or mounted nearby on theground.

Arrays are most often retrofittedinto existing buildings, usuallymounted on top of the existing roofstructure or on the existing walls.

Alternatively, an array can belocated separately from thebuilding but connected by cable tosupply power for the building. In2010, more than four-fifths of the9,000 MW of solar PV operating inGermany were installed on

rooftops


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Building-integrated photovoltaics (BIPV) areincreasingly incorporated into new domestic andindustrial buildings as a principal or ancillarysource of electrical powerTypically, an array is

incorporated into the roof or walls of a building.Roof tiles with integrated PV cells are alsocommon. A 2011 study using thermal imaging hasshown that solar panels, provided there is anopen gap in which air can circulate between them

and the roof, provide a passive cooling effect onbuildings during the day and also keepaccumulated heat in at night.The power output ofphotovoltaic systems for installation in buildings is

usually described in kilowatt-peak units (kWp)
http://en.wikipedia.org/wiki/Kilowatt-peakhttp://en.wikipedia.org/wiki/Kilowatt-peakhttp://en.wikipedia.org/wiki/Kilowatt-peakhttp://en.wikipedia.org/wiki/Kilowatt-peak


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Solar vehicles are not sold as practical day-to-daytransportation devices at present, but are primarily

demonstration vehicles and engineering exercises, oftensponsored by government agencies. However, indirectlysolar-charged vehicles are widespread and solar boatsare available commercially

Solar energy is often used to supply power for satellites

and spacecraft operating in the inner solar system sinceit can supply energy for a long time without excess fuelmass. A Communications satellite contains multiple radiotransmitters which operate continually during its life. Itwould be uneconomic to operate such a vehicle (which

may be on-orbit for years) from primary batteries or fuelcells, and refuelling in orbit is not practical. Solar poweris not generally used to adjust the satellite's position,however, and the useful life of a communicationssatellite will be limited by the on-board station-keeping

fuel supply.
http://en.wikipedia.org/wiki/Electric_boathttp://en.wikipedia.org/wiki/Electric_boat


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3.Standalone devices Until a decade or so ago, PV was used frequently

to power calculators and novelty devices.Improvements in integrated circuits and lowpower liquid crystal displays make it possible to

power such devices for several years betweenbattery changes, making PV use less common. Incontrast, solar powered remote fixed deviceshave seen increasing use recently in locations

where significant connection cost makes gridpower prohibitively expensive. Such applicationsinclude water pumps, parking meters,emergencytelephones, trash compactors, temporary traffic

signs, and remote guard posts and signals.


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Solar water pump


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4. Rural electrification Unlike the past decade, which saw solar solutions

purchased mainly by international donors, it is nowthe locals who are increasingly opening their walletsto make the switch from their traditional energymeans. That is because solar products prices in

recent years have declined to become cheaper thankerosene and batteries.

In Cambodia, for example, villagers can buy a solarlantern at US$25 and use it for years without any

extra costs, where their previous spending onkerosene for lighting was about $2.5 per month, or$30 per year. In Kenya a solar kit that provides brightlight or powers a radio or cell phone costs under $30at retail stores. By switching to this kit Kenyans can

save $120 per year on kerosene lighting, radiobatteries and cell phone recharging fees.


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Developing countries where many villages areoften more than five kilometers away from gridpower are increasingly using photovoltaics. Inremote locations in India a rural lighting program

has been providing solar powered LED lighting toreplace kerosene lamps. The solar poweredlamps were sold at about the cost of a fewmonths' supply of kerosene. Cuba is working to

provide solar power for areas that are off grid.These are areas where the social costs andbenefits offer an excellent case for going solarthough the lack of profitability could relegate such

endeavors to humanitarian goals.


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5. Solar Highways A solar roadway is a road surface that generates

electricity by solar power photovoltaics. One currentproposal is for 12 ft x 12 ft (3.658 m x 3.658 m) panelsincluding solar panels and LED signage, that can bedriven on. The concept involves replacing highways,

roads, parking lots, driveways, and sidewalks withsuch a systemA solar roadway is a series ofstructurally engineered solar panels that are drivenupon. The idea is to replace current petroleum-basedasphalt roads, parking lots, and driveways with solarroad panels that collect energy to be used by homesand businesses, and ultimately to be able to storeexcess energy in or alongside the solar roadways.Thus renewable energy replaces the need for thecurrent fossil fuels used for the generation ofelectricity, which cuts greenhouse gases.


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Parking lots, driveways, and eventually highwaysare all targets for the panels. If the entire United

States Interstate Highway system were surfacedwith Solar Roadways panels, it would producemore than three times the amount of electricitycurrently used nationwide.


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Advantages

1. The 89 PW of sunlight reaching the Earth's surface is plentiful

almost 6,000 times more than the 15 TW equivalent of averagepower consumed by humansAdditionally, solar electric generationhas the highest power density (global mean of 170 W/m2) amongrenewable energies

2. Solar power is pollution-free during use. Production end-wastes andemissions are manageable using existing pollution controls. End-of-use recycling technologies are under development and policies arebeing produced that encourage recycling from producers

3. PV installations can operate for many years with little maintenance orintervention after their initial set-up, so after the initial capital cost ofbuilding any solar power plant, operating costs are extremely lowcompared to existing power technologies.

4. Grid-connected solar electricity can be used locally thus reducingtransmission/distribution losses (transmission losses in the US wereapproximately 7.2% in 1995).Compared to fossil and nuclear energysources, very little research money has been invested in thedevelopment of solar cells, so there is considerable room forimprovement. Nevertheless, experimental high efficiency solar cells

already have efficiencies of over 40% in case of concentratingphotovoltaic cells and efficiencies are rapidly rising while mass-


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Economic Aspects The output of a photovoltaic array is a product of thearea, the efficiency, and the insolation. The capacity

factor, or duty cycle, of photovoltaics is relatively low,typically from 0.10 to 0.30, as insolation ranges, bylatitude and prevailing weather, and is locationspecific from about 2.5 to 7.5 sun hours/day. Panelsare rated under standard conditions by their outputpower. The DC output is a product of the rated outputtimes the number of panels times the insolation timesthe number of days. The sunlight received by thearray is affected by a combination of tilt, tracking and

shading. Tracking increases the yield but also thecost, both installation and maintenance. A dual axistracker can increase the effective insolation byroughly 3540%, while temperature effects canreduce efficiency by 10%. The AC output is roughly

25% lower due to various losses including theefficiency of the inverter.


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Financial incentives for photovoltaics,such as feed-in tariffs, have often

been offered to electricity consumersto install and operate solar-electricgenerating systems. Government hassometimes also offered incentives inorder to encourage the PV industry toachieve the economies of scale

needed to compete where the cost ofPV-generated electricity is above thecost from the existing grid. Suchpolicies are implemented to promotenational or territorial energyindependence, high tech job creationand reduction of carbon dioxide

emissions which cause globalwarming. Due to economies of scalesolar panels get less costly as peopleuse and buy more asmanufacturers increase production tomeet demand, the cost and price isexpected to drop in the years to come


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Solar cell efficiencies vary from 6% for amorphoussilicon-based solar cells to 43.5% with multiple-

junction concentrated photovoltaics.Solar cell energy

conversion efficiencies for commercially availablephotovoltaics are around 14-22%.

There has been fierce competition in the supply chain,and further improvements in the levelised cost of

energy for solar lie ahead, posing a growing threat tothe dominance of fossil fuel generation sources in thenext few years.As time progresses, renewable energytechnologies generally get cheaper,while fossil fuelsgenerally get more expensive


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References www.wikipedia.com www.google.com

Non-conventional Energy Resources G.D. Rai,Khanna publishers
http://www.wikipedia.com/http://www.google.com/http://www.google.com/http://www.wikipedia.com/


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Ncer Presentation on Photovoltaics

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