Photovoltaic Power Generation and Application

7/30/2019 Photovoltaic Power Generation and Application

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Contents:

Introduction.

Types of Photo Voltaic cells.

PV Parameters & Standard Test Conditions.

Classification Of PV Applications.

PV Cell & Module Manufacturers.

Area & Cost of PV Power Generation.

Conclusion.

References.


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Introduction:

The basic components ofa photovoltaic power system are- the photovoltaic cells (sometimes also called solar cells) interconnected to form aphotovoltaic module (the commercial product),

- the mounting structure for the module or array,

- the inverter (essential for grid-connected systems and required for most off-gridsystems),

- the storage battery and charge controller (for off-grid systems only).


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Photovoltaic cells represent the smallest unit in a photovoltaic power producing device,typically available in 12.5 cm, 15 cm and up to 20 cm square sizes

In general, cells can be classified as either wafer-based crystalline (single crystal or multicrystalline) or thin film.

Currently wafer-based crystalline silicon technologies account for most of the overall cellproduction in the IEA PVPS countries.

(IEA PVPS International Energy Agency Photo Voltaic Power System)

Types of Photovoltaic cells:


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Types of Photovoltaic cells:

Single crystal silicon (sc-Si) PV cells:

- manufactured using a single crystal growth method.- commercial efficiencies between 15 % to 18 %.

Multi-crystalline silicon (mc-Si) cells,:- manufactured from melting and solidification process.- less expensive to produce but are marginally less efficient,

- average conversion efficiency around 14 %.

Thin film cells :- manufactured by depositing extremely thin layers of photovoltaic semi-conductormaterials onto a backing material such as glass, stainless steel or plastic.- module conversion efficiencies ranging from 7 % to 13 %.

- cheaper to manufacture than crystalline cells.


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Photovoltaic Module: Photovoltaic modules are typically rated between 50W to 300W with specialized

products for building integrated PV systems at even larger sizes. Crystalline silicon modules consist of individual PV cells connected together and

encapsulated between a transparent front, usually glass, and a backing material, usuallyplastic or glass.

Thin film modules are constructed from single sheets of thin film material and can beencapsulated in the form of a flexible or fixed module, with transparent plastic or glass as

front material. Quality PV modules are typically guaranteed for up to 20 years by manufacturers.

Mono Crystalline

Module

Multi Crystalline

Module

Thin Film

Module
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Module Inter-Connections:

A PV array consists of a number of modules connected in series (strings), then coupled inparallel to produce the required output power.


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PV Mounting Structures:

A wide range of mounting structures has been developed especially for buildingintegrated PV systems (BIPV), including PV facades, sloped and flat roof mountings,integrated (opaque or semi-transparent) glass-glass modules and PVrooftiles.

Building Integrated Building Facades Opaque Modules

PV Roof Tiles PV Terracotta Roof Tiles PV Roof Tiles
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Solar Tracking Systems:

Single or dual-axis tracking systems have recently becomemore and more attractive, particularly for PV applications incountries with a high share of direct irradiation.

By using such systems, the energy yield can be typicallyincreased by about 30 % compared with non-tracking systems.

Single Axis Trackers:

Dual Axis Trackers:


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Inverters: In grid-connected PV-systems, an inverter is used to convert electricity from direct

current (d.c.) as produced by the PV array to alternating current (a.c.) that is thensupplied to the electricity network.

The conversion Efficiency of inverters is in the range of95 % to 98 %.

Inverters connected directly to the PV array incorporate a Maximum Power Point Tracker(MPPT), which continuously adjusts the load impedance to provide the maximum powerfrom the PV array.

One inverter can be used for the whole array or separate inverters may be used for eachstring of modules.

PV modules with integrated inverters, usually referred to as AC modules, can be directly

connected to the electricity network (where approved by network operators) but still playa very limited role.


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Battery:

For off-grid systems a storage battery is required to provide energy during low-lightperiods.

Nearly all batteries used for PV systems are of the deep discharge lead-acid type.

Other types of batteries (e.g. NiCad) are also suitable and have the advantage that theycannot be overcharged or deep-discharged, but are considerably more expensive.

The lifetime of a battery varies depending on the operating regime and conditions but is

typically between 5 and 10 years.

Nickel Cadmium

BatteryNickel Metal Hydride

Battery

Lead Acid

Battery
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PV Parameters & Standard Test Conditions :

The electrical generation capacity of PV modules is given in watts (W). It depends on short circuit current (Isc) , open circuit voltage (Voc) of the module and

the temperature.

This represents the rated power of a PV device under standard test conditions of -

1000W/m2irradiance,

25C cell junction temperature and solar reference spectrum AM 1.5.


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Classification of PV Applications:

Off-grid domestic systems. Off-grid non-domestic systems.

Grid-connected distributed systems.

Grid-connected centralized systems.


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Off-grid domestic systems:

Off-grid domestic systems provide electricity to households and villages that are notconnected to the utility electricity network (grid).

They provide electricity for lighting, refrigeration and other low power loads.

Typically around 1 kW in load.

Offer an economic alternative to extending the electricity distribution network atdistances of more than 1 or 2 km from existing power lines.


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Off-grid non-domestic systems:

Off-grid non-domestic installations were the first commercial application for terrestrial PVsystems.

They provide power for a wide range of applications, such as telecommunication, waterpumping, vaccine refrigeration and navigational aids.

These are applications where small amounts of electricity have a high value, thus makingPV commercially cost competitive with other small generating sources.


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Grid-connected distributed systems:

Grid-connected distributed PV systems are installed to provide power to a grid-connectedcustomer or directly to the electricity network.

Such systems may be on or integrated into the customers premises often on

the demand side of the electricity meter, on public and commercial buildings, or simplyin the built environment etc.

Size is not a determining feature .

while a 1-20KW PV system on a roof-top may be large by PV standards, this is not thecase for other forms of distributed generation.


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Grid-connected centralized system:

Grid-connected centralized systems perform the functions of centralized power stations. The power supplied by such a system is not associated with a particular electricity

customer, and the system is not located to specifically perform functions on theelectricity network other than the supply of bulk power.

These systems are typically ground-mounted and functioning independently of anynearby development.


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Conclusion:

Solar photovoltaic based power and energy systems is gaining recognition due to the

availability and high solar insolation in most parts of India and its inherent advantage of

direct conversion to power unlike a solar thermal system.

Solar Photovoltaic technology, its application in the remote areas, its advantage as a stand

alone system, environment friendly and tireless source are some of the positive features

of this wonderful source of nature.


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References:

Trends in photovoltaic applications, Report IEA-PVPS T 1-18:2009

Solar photovoltaic as an energy source for India, Anantha, A.

India Solar PV Advisor , Energy Alternatives India.

www.mnre.gov.in

www.google.com


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Thank You

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Photovoltaic Power Generation and Application