CHAPTER 5 RENEWABLE ENERGY SYSTEMS. SOLAR ENERGYsite.iugaza.edu.ps/aabuzarifa/files/ES20152_Ch5.pdf · Arnedo Solar Plant Spain 34 Completed October 2008 Merida/Don Alvaro Solar Park

CHAPTER 5RENEWABLE ENERGY SYSTEMS.SOLAR ENERGY

Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering

Introduction Renewable energy is generally defined as energy that comes from

resources which are naturally replenished on a human timescale suchas sunlight, wind, rain, waves and geothermal heat.

Wind, solar, and biomass are three emerging renewable sources ofenergy.

Renewable energy can basically be classified in three categories:renewables for transport, renewables for electricity and renewablesfor heat.

In international public opinion surveys there is strong support forpromoting renewable sources such as solar power and wind power.

At the national level, at least 30 nations around the world alreadyhave renewable energy contributing more than 20 percent of energysupply.*

*REN21, the Renewable Energy Policy Network for the 21st Century: "Renewables global futures report2013“

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Dr. Anwar Abu-Zarifa . Islamic University Gaza . Department of Industrial Engineering 3


Solar Energy Solar power has a longhistory as energy source forhumans. For example, solarpower was used for heatingof water in the Romanempire.

A steam engine based onsolar power was constructedby Auguste Mouchout in1861, but was found to be fartoo expensive to have acommercial value.

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The Earth receives 174 petawatts (PW) of incoming solarradiation (insolation) at the upper atmosphere.Approximately 30% is reflected back to space while therest is absorbed by clouds, oceans and land masses.

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The Sun and Radiation• The sun

1.4 million km in diameter 3.8 x 1020 MW of radiated electromagnetic energy

Energy from the sun in the form of ultra‐violet, visible and infra‐redelectromagnetic radiation is known as solar radiation.

Insolation (from Latin insolare, to expose to the sun) is the totalamount of solar radiation energy received on a given surface areaduring a given time. It is also called solar irradiation and expressed as"hourly irradiation" if recorded during an hour or "daily irradiation" ifrecorded during a day.

Practitioners in the business of solar energy may use the unit watt‐hour per square meter (Wh/m2). If this energy is divided by therecording time in hours, it is then a density of power calledirradiance, expressed in watts per square meter (W/m2).

The intensity of energy arriving from the sun in space just outside theearth’s atmosphere is approximately 1367 W/m2, called the solarconstant. Although it is termed a “constant,” it varies over time.

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Average insolation, or solar energy reaching a givenlocation on earth, will be lower than the amount availableoutside the atmosphere due to absorption and diffractionof sunlight in the atmosphere, changing weather, loss ofsunlight at night, and so on.

Worldwide average values for some representative cities,taking all these factors into account, range between 100W/m2 for Glasgow, Scotland, and 280 W/m2 for Cairo,Egypt.

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Solar Insolation I0 I0 depends on distance between earth and sun and onintensity of the sun.

Ignoring sunspots, I0 can be written as

SC = solar constant = 1.377 kW/m2 n = day number (January 1 is day 1; December 31 is day 365).n is also called the “Julian date,” from the Julian calendar

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360SC 1 0.034cos (W/m ) 365

nI



Solar Declination Solar declination δ – the angle formed between the planeof the equator and the line from the center of the sun tothe center of the earth

δ varies between +/‐ 23.45˚ Assuming a sinusoidal relationship,a 365 day year, and n=81 is thespring equinox, the approximationof δ for any day n can be found from:

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36023.45sin 81365

n


Altitude Angle and Azimuth Angle

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Azimuth Angle

Altitude Angle

http://www.pveducation.org/pvcdrom/properties‐of‐sunlight/azimuth‐angle


Solar Basic Processes Three processes have been implemented in practice to transform the

solar radiations into energy: Solar photovoltaics (PV), passive solarpower (PSP) and concentrated solar power (CSP).

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Solar photovoltaics (PV) Solar Cells Background

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1839 ‐ French physicist A. E. Becquerel first recognized the photovoltaiceffect.

Photo+voltaic = convert light to electricity

1883 ‐ first solar cell built, by Charles Fritts, coated semiconductor seleniumwith an extremely thin layer of gold.

1956 ‐ Bell Laboratories, experimenting with semiconductors, accidentallyfound that silicon doped with certain impurities was very sensitive to light.

Daryl Chapin, Calvin Fuller and Gerald Pearson, invented the first practicaldevice for converting sunlight into useful electrical power. Resulted in theproduction of the first practical solar cells with a sunlight energyconversion efficiency of around 6%.

1958 ‐ First spacecraft to use solar panels was US satellite Vanguard


“Bell System Solar Battery Converts Sun’s Rays into Electricity”, Advertisement from Look Magazine, 1956.


The solar cells in the early 1950s were about 0.5 %efficient. Today amodule is about 20 % efficient.

A 1 kW system:

In 1950 = 2,400 square feet

In 2005 = 80 Square feet


Annual output of world PV manufacturing and average cost per rated watt of panels, 1975 to 2003.


Global Cumulative PV Power

http://www.epia.org/fileadmin/EPIA_docs/publications/epia/Global_Market_Outlook_Until_2013.pdf


Cumulative installed solar electric power by 2007

1st Germany 3.8 GW2nd Japan 1.9 GW3rd US 814 MW4th Spain 632 MW

World's largest photovoltaic (PV) power plants (12 MW or larger)Name of PV power plant Country DC

PeakPower(MW)

GW·h/year

Notes

Olmedilla Photovoltaic Park Spain 60 85 Completed September 2008

Puertollano Photovoltaic Park Spain 50 2008

Moura photovoltaic power station Portugal 46 93 Completed December 2008

Waldpolenz Solar Park Germany 40 40 550,000 First Solar thin-film CdTe modules. Completed Dec 2008

Arnedo Solar Plant Spain 34 Completed October 2008

Merida/Don Alvaro Solar Park Spain 30 Completed September 2008

17 more 2 more

SpainKorea

Avg 20Avg 20

Koethen Germany 14.75 13 200,000 First Solar thin-film CdTe modules. Completed Dec 2008

Nellis Solar Power Plant USA 14.02 30 70,000 solar panels

Planta Solar de Salamanca6 more Spain, 1 US, 1 Germany

Spain 13.8Avg 12

n.a. 70,000 Kyocera panels

http://en.wikipedia.org/wiki/Photovoltaic_power_stations


Germany 10,000 companies, including installers work in solar PV

80 companies are cell and module makers

42,000 employees

Sales were $5.7 B including $2.5 B in exports

The ‘feed‐in’ tariff 2008 German utilities pay $0.47 to $0.68/kWh depending on type and size of

system for new solar systems

www.epia.org Solar Generation V Report Sep 2008


Waldpolenz Solar Park The Waldpolenz Solar Park is built on a surface areaequivalent to 200 soccer fields, the solar park will becapable of feeding 40 megawatts into the power gridwhen fully operational in 2009.

http://www.dw-world.de/dw/article/0,2144,3430319,00.html


Waldpolenz Solar Park

http://lumbergusa.com/main/Bild/sp_pv_07/Brandis-Waldpolenz-Fotomont.jpg


The Major PV Cell/Module Manufacturers


Photovoltaic (PV) Hierarchy Cell < Module < Panel < Array


Overview of PV Function

How PV cells work: A photovoltaic cell can convert sunlight into DC current. The working principle of photovoltaic cell is largely depending on the characteristic of a semiconductor.

A semiconductor consists of two types of materials which are p‐type silicon and n‐type silicon these two made up the internal circuit.

Due to this characteristic, light of specific wavelength will be able to ionize the atom in the silicon. This causes the electron to move freely and is pulled towards the n‐type semiconductor and the holes produced will move to the p‐type semiconductor this is called photovoltaic effect.

The electricity will flow normally when the outside circuit is closed.


Overview of PV Function

Available Cell Technologies Single‐crystal or Mono‐crystalline Silicon

Polycrystalline or Multi‐crystalline Silicon

Thin film Ex. Amorphous silicon or Cadmium Telluride


Effect of Material Choice on EfficiencyBasic Si Types Monocrystalline: <25% (but expensive) Multicrystalline: <20% (lower cost offsets lower efficiency) Amorphous: <13% (increased from 4% in 1978)Other emerging materials: Gallium Arsenide, Cadmium Telluride, Copper IndiumDiselenide

Monocrystalline Silicon Modules

Most efficient commercially available module (11% ‐ 14%)

Most expensive to produce

Circular (square‐round) cell creates wasted space on module

Polycrystalline Silicon Modules

Less expensive to make than single crystalline modules

Cells slightly less efficient than a single crystalline (10% ‐ 12%)

Square shape cells fit into module efficiently using the entire space

Amorphous Thin Film Most inexpensive technology to produce

Metal grid replaced with transparent oxides

Efficiency = 6 – 8 % Can be deposited on flexible substrates

Less susceptible to shading problems

Better performance in low light conditions that with crystalline modules

Selecting the Correct Module Practical Criteria

Size Voltage Availability Warranty Mounting Characteristics Cost (per watt)


Problems by solar cellsEffects of Temperature

Effects of Temperature As the PV cell temperature increases above 25º C, themodule Vmpdecreases by approximately 0.5% per degree C.

Shading onModules Depends on orientation ofinternal module circuitry relativeto the orientation of the shading. SHADING can halfor even completelyeliminate the outputof a solar array!


PV System

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A photovoltaic system, also photovoltaic power system,solar PV system, PV system or casually solar array, is apower system designed to supply usable solar power bymeans of photovoltaics.

It consists of an arrangement of several components,including solar panels to absorb and directly convertsunlight into electricity, a solar inverter to change theelectrical current from DC to AC, as well as mounting,cabling and other electrical accessories to set‐up a workingsystem.

It may also use a solar tracking system to improve thesystem's overall performance or include an integratedbattery solution.

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PV System


Off‐Grid

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Grid‐off solar energy power generating

Main used in the area where is no electricity supply or thetelecommunication station which is faraway from theelectricity net or the wireless places.

Key components: solar panel、battery、intelligentcontroller、inverter、and electricity distribution.(electricity distribution is close to the active load).

Advantages: offer the independent electricity net whichwill not restricted by the local public electricity net.

Disadvantages：much waste of the energy resources orcan controller the use of the solar energy resources. theelectricity use is high restricted by the weather condition,the low efficiency of use and high investment( large solarbatteries and a battery bank).

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On‐Grid

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On‐Grid PV System

Main use in the place where the city electricity distributionnet. It is the lead direction of New energy from home andall over the world.

Key components: solar panel、grid‐on inverter、electricity distribution.

Advantages：high efficient use of the system，long lifespan；the investment cost is some lower

Disadvantages: Homes must be located close to powerlines, as grid‐tied power systems require connection withthe local utility. Grid‐tied system installations requirelarge roof surface areas in sunny locations.

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Solar Power Plants There are two ways we can produce electricity from thesun:

Photovoltaic Electricity – This method uses photovoltaiccells that absorb the direct.

Solar‐Thermal Electricity – This also uses a solar collector:it has a mirrored surface that reflects the sunlight onto areceiver that heats up a liquid. This heated liquid is used tomake steam that produces electricity.

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Photovoltaic Electricity: PV Power Plants (station) A photovoltaic power station, also known as a solar park, is alarge‐scale photovoltaic system (PV system) designed for thesupply of merchant power into the electricity grid.

They are differentiated from most building‐mounted and othersolar power applications because they supply power at theutility level, rather than to a local user or users.

The power conversion source is via photovoltaic modules thatconvert light directly to electricity.

should not be confused with concentrated solar power, theother large‐scale solar generation technology, which uses heatto drive a variety of conventional generator systems. Bothapproaches have their own advantages and disadvantages, butto date, for a variety of reasons, photovoltaic technology hasseen much wider use in the field. As of 2013, PV systemsoutnumber concentrators by about 40 to 1.

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Technology: Most Solar parks are ground mounted PV systems, also known asfree‐field solar power plants.

They can either be fixed tilt or use a single axis or dual axis solartracker

While tracking improves the overall performance, it also increasesthe system's installation and maintenance cost.

A solar inverter converts the array's power output from DC to AC,and connection to the utility grid is made through a high voltage,three phase step up transformer of typically 10 kV and above.

Solar panels produce direct current (DC) electricity, so solar parksneed conversion equipment.

to convert this to alternating current (AC), which is the formtransmitted by the electricity grid. This conversion is done byinverters.

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Construction of on‐grid PV power plants

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Topaz Solar Farm from space. Earth Observatory image, 2015.

Topaz Solar Farm is a 550‐megawatt (MW) photovoltaic power station in San Luis, California. Construction on the project began in November 2011 and ended in November 2014. It is the world’s largest solar farm.


Solar thermal electricity: Concentrated Solar Power (CSP) CSP is a technique to increase the conversion efficiency by increasing

the incoming flux to the medium to be heated. By constructing mirrors which focus all the incoming radiation towards

a small concentrated spot containing the fluid, the conversionefficiency per mirror area can be made almost proportional to theconstant c1 in Eq. (4.2).

The radiation energy, often of the order of 50 % is lost in the mirrorsystem.

The temperature of the working fluid is nevertheless easily brought tomany hundred degrees. This much higher fluid temperature can becombined with a turbine or engine system to produce electricity.

By assuming 100 % efficiency of the fluid to absorb the radiation, theefficiency of the electricity production process then depends in generalon two factors: The efficiency of the mirrors and the efficiency of theengine which converts heat to electricity.

The three main types of concentrating solar power systems are: linearconcentrator, power tower systems and dish/engine.

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Linear concentrator systems*

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Linear concentrator systems capture thesun's energy with large mirrors that reflectand focus the sunlight onto a linear receivertube. The receiver contains a fluid that isheated by the sunlight and then used tocreate steam that spins a turbine generatorto produce electricity. Alternatively, steamcan be generated directly in the solar field,eliminating the need for costly heatexchangers. Currently, individual systemscan generate about 80 megawatts ofelectricity.

*Source: The U.S. Energy Information Administration (EIA)


Power Tower System

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Power tower systems consist ofnumerous large, flat, sun-tracking mirrors,known as heliostats that focus sunlightonto a receiver at the top of a tower. Theheated fluid in the receiver is used togenerate steam, which powers a turbineand a generator to produce electricity.Some power towers use water/steam asthe heat-transfer fluid. Individualcommercial plants can be sized toproduce up to 200 megawatts ofelectricity.


Dish/engine systems

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Dish/engine systems use parabolic dishesof mirrors to direct and concentrate sunlightonto a central engine (Stirling engine) thatproduces electricity. The dish/engine systemproduces relatively small amounts ofelectricity compared to other CSPtechnologies‐typically in the range of 3 to 25kilowatts.


Media

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https://www.youtube.com/watch?v=BXnNIaWiykU https://www.youtube.com/watch?v=O_QKxk9coKE


Presentation 8: PV solar economic analysis Presentation 9: Solar Energy in Palestine

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Documents

CHAPTER 5 RENEWABLE ENERGY SYSTEMS. SOLAR ENERGYsite.iugaza.edu.ps/aabuzarifa/files/ES20152_Ch5.pdf · Arnedo Solar Plant Spain 34 Completed October 2008 Merida/Don Alvaro Solar Park