Sun: Energy source of the future
Dr Adil Sarwar
Layout of the Presentation
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Need for sustainable source of energy
Solar energy: direct and indirect
Main features of terrestrial solar radiation
Solar radiation spectrum
Insolation
Solar data
Resource estimation and measurement
Overview of thermal and PV applications, solar heat collectors
Need for sustainable source of energy
World Energy Consumption
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World Energy Consumption by Source, Based on Vaclav Smil estimates from Energy Transitions: History, Requirements and Prospects together with BP Statistical Data for 1965 and subsequent
Our Dependence on fossil fuels.
Adverse effects of indiscriminate
use of fossil fuels
Pollution
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Global warming, rise in Sea Level Oil spill, destruction
of marine life
Depletion of Ozone Layer Environmental Impact
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Global distribution of coal
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Coal deposit in India
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Historical Incidents
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First Oil Crisis ( October 1973) and Second Oil Crisis(1979).
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Chernobyl Accident: Nuclear Disaster(26 April 1986)
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Fukushima Nuclear Disaster (11 March 2011)
Moving to Renewable
Sources of Energy
Renewable Sources of Energy
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1. Wind 2. Solar 3. Tidal 4. Geothermal
Free
Inexhaustible
Availability in a large part of the world
No or Low Pollution
Low Maintenance (Especially in Solar PV-there is no moving part)
Solar energy: Direct and
Indirect
Solar Radiation
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The sun is sending us radiation over a wide range of wavelengths at varying intensities. The electro- magnetic solar radiation impinging on the upper edge of the atmosphere is called extra-terrestrial radiation. The mean integral for the complete
spectrum is 1,367 W/m² (the Solar Constant).
The complete spectrum comprises the ultraviolet (UV), visible (Vis) and infrared (IR) wavelengths
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Solar radiation is the driver for many chemical, biological and physical phenomena in the
atmosphere, on the ground and in the seas.
A major effect of solar radiation reaching the earth’s surface is that it is warming it up, which is vital for our existence. 30% of the extra-terrestrial radiation solar radiation is reflected back into
space but approximately 51% is absorbed by land and water and another 19% is absorbed by the
clouds and atmosphere.
Earths energy budget
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Solar Radiation attenuation
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The attenuation of solar radiation passing through our atmosphere is due to the following processes:
ultraviolet range
Scattering by molecules and aerosol particles and
absorption by Ozone, Sulphur Dioxide, Nitrogen Dioxide and trace gases.
visible range
Scattering by molecules and aerosol particles, little
absorption by aerosol particles, Ozone and other trace gases.
infrared range
Absorption by water vapour and aerosol particles but little scattering.
Advantages of analyzing solar radiation
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Nowadays, measuring solar radiation is extremely important in many different fields of application, such as climatology, meteorology, hydrology,
pollution forecasting, solar energy, agriculture and material testing.
Solar Spectra
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Air Mass(AM)
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The air mass coefficient defines the direct optical path length through the Earth's atmosphere, expressed as a ratio
relative to the path length vertically upwards, i.e. at the zenith.
The air mass coefficient can be used to help characterize the solar spectrum after solar radiation has traveled through the atmosphere.
The air mass coefficient is commonly used to characterize the performance of solar cells under standardized
conditions, and is often referred to using the syntax "AM"
Contd..
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For a path length “L” through the atmosphere, for solar radiation incident at angle “z” relative to the normal to the Earth's surface, the air mass coefficient is
AM=L/Lo=1/sin z,
where Lo is the zenith path length (i.e. normal to the
Earth's surface) at sea level and z is the zenith angle in degrees.
The air mass number is thus dependent on the Sun's
elevation path through the sky and therefore varies with time of day and with the passing seasons of the year, and with the latitude of the observer.
Terms associated with solar spectrum
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AM0
The spectrum outside the atmosphere, approximated by the 5,800 K black body, is referred to as "AM0", meaning "zero atmospheres". Solar cells used for
space power applications, like those on communication satellites are generally characterized using AM0.
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AM1
The spectrum after travelling through the atmosphere to sea level with the sun directly overhead is referred to, by definition, as "AM1". This means "one
atmosphere". AM1 (z=0°) to AM1.1 (z=25°) is a
useful range for estimating performance of solar cells in equatorial and tropical regions.
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AM1.5
Solar panels do not generally operate under exactly one atmosphere's thickness: if the sun is at an angle to the Earth's surface the effective thickness will be greater.
Many of the world's major population centres, and hence solar installations and industry, across Europe, China, Japan, the United States of America and elsewhere (including northern India, southern Africa and Australia) lie in temperate latitudes. An AM number
representing the spectrum at mid-latitudes is therefore much more common.
"AM1.5", 1.5 atmosphere thickness, corresponds to a solar zenith angle of z=48.2°. While the summertime AM number for mid-latitudes during the middle parts of the day is less than 1.5, higher figures apply in the
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Air Mass definition
Solar Energy Distribution
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Solar Irradiance vs Solar Insolation
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Solar Irradiance (power density) refers to the rate of energy received by a surface per unit area. It is the flux of solar energy. Unit is W/m2.
Solar Insolation (Energy density) refers to the amount of energy received by a surface over a
given period of time. It is the integrated irradiance over a time. Unit is WHr/m2.
Solar Constant
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The average amount of solar radiation received by the Earth's atmosphere,per unit area, when the Earth is at its mean distance from the Sun. It isequal to 13 67 watts per square meter. Solar radiation varies w ith theEarth's distance from the Sun and with the ap pearance or decay ofsunspots.
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Solar Energy
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Solar Thermal
Solar Photovoltaic
Grid
Application Street Lighting and Traffic
Agriculture
Residential and health Transportation
Solar PV Application
Space
Application
Solar Potential in India
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Solar Potential (GWp)
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38.44
8.65 13.76 11.2
18.27 2.05
0.88
35.77
4.56
33.84
111.05
18.18 24.7
5.86 9.09 7.29
25.78 2.81
142.31 4.94
17.67
20.41 2.08
22.83 16.8
6.26 0.79
Andhra Pradesh Arunachal Pradesh Assam
Bihar
Chhattisgarh Delhi
Goa Gujrat Haryana
Himachal Pradesh Jammu & Kashmir Jharkhand
Karnataka Kerela
Madhya Pradesh Maharashtra Manipur Meghalaya Mizoram Nagaland Orissa Punjab Rajasthan Sikkim Tamil Nadu Telangana
Uttar Pradesh 22.83 GWp
Initiatives by Indian Government
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Ministry of new and renewable energy under government of India is dedicated to planning,
development, research and implementation in the area of renewable energy
National Solar Mission is an ambitious project to generate 100 GW of electricity from solar energy.
70% of it through Solar PV alone both by grid and off grid applications by 2021.
Solar PV-Indian Scenario
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Charanka Solar Park ( Gujrat)
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Recently Madhya Pradesh Cabinet has approved construction of 750MW solar PV plant in Rewa
Global PV market
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5000 10000 15000 20000 25000
MW
CHINA US JAPAN INDIA
Global Solar PV installed
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Observation by Global data
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The global cumulative installed capacity for solar Photovoltaic (PV) power will rise from 178 Gigawatts (GW) in 2014 to an estimated 223.2 GW in 2015
China will remain the world’s largest market for annual solar PV installations in 2015, adding around 17.6 GW this year.
The US will follow with almost 8.2 GW of additions.
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Solar PV- Challenges
1. Efficiency
Solar Cell Technology Options
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Crystalline Silicon solar cells - Single, Multi, Ribbon
Thin Film solar cells
- Silicon, a-Si, m-Si, CdTe,
CIGS
Solar Cell Technology Options
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Concentrating solar cells - Si, GaAs
Dye, Organic, Nano-materials & other emerging solar cells
Best Research Cell Efficiency
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Solar PV- Challenges
2. Cost
Swanson Effect-Price of Solar PV
Solar PV- Indian Market
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0 10 20 30 40 50 60
Rs Per Watt
Parameters
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Solar PV- Challenges
3. Intermittent nature
I-V and P-V characteristics of a PV cell
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5 10 15 20 25
Power (Watts)
I-V Characteristic P-V Characteristic
Maximum Power Point
P-V characteristics (Uniformly Shaded Panels)
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0 5 10 15 20 25
0 10 20 30 40 50 60 70
Voltage(volts)
Power(watts)
1000W/m2,30C 1000W/m2,40C 1000W/m2,50C 800W/m2,50C 800W/m2,40C 800W/m2,30C 400W/m2,30C 400W/m2,50C 800W/m2,40C
Insolation Increasing
Temperature
Increasing MPP
Partial Shading
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Uneven illumination of PV panels connected in series and parallel.
1. Cloud
Solar PV panels are connected in series and parallel to enhance the power
handling capability
P-V characteristics (Partial Shading)
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0 2 4 6 8 10 12 14
0 5 10 15 20 25 30
Voltage (Volts)
Power(Watts)
1000,200 1000, 350 1000,400 1000, 600 1000,300
Insolation level on two Panels in Watts/m2
Maximum Power Points
Local Maxima
Global Maxima
With Complex shading pattern no. of Peaks increases
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10 20 30 40 50 60 70
Power (W)
Ir1=1000,Ir2=800,Ir3=200 Ir1=1000,Ir2=800,Ir3=400 Ir1=1000,Ir2=800,Ir3=600
Three Local Maxima
Maximum Power Point Trackers
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Mechanical Tracker: 1. Single Axis Tracking
2. Dual Axis Tracking
Mechanical movement of panel to keep it facing the sun.
Electronic Tracker: A DC/DC converter with MPPT enabled control algorithms for switching
Stand alone application
PV Panel
Hybrid output Converter for Micro grid Applications
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AC Load
S1 S3
S4 S2
DC-DC Buck Converter with
MPPT
PV Array DC Load
Digital Signal Controller
From load and PV
L C
Maximum Power Point Tracking
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Conventional MPPT algorithms
MPPT technique
Convergence speed
Implementation complexity
Periodic tuning
Sensed parameters
Perturb &
observe
Varies Low No Voltage
Incremental conductance
Varies Medium No Voltage,
current
Fractional Voc Medium Low Yes Voltage
Fractional Isc Medium Medium Yes Current
MPPT Algorithms for Partial Shading
Methods Advantages Disadvantages
System
characteristic curve method
Good tracking speed
Requirement of open or short circuits can cause power loss
or safety concerns, method fails in some cases
Two stage searching method
Its implementation is easy and it can be integrated into
traditional PGS
It can fail to track GMPP in some cases
Direct method
Based on a solid mathematical foundation and good tracking
speed
Cannot be directly integrated into traditional PGS
Fibonacci methods Based on a solid mathematical foundation
Fail to track GMPP in some cases and cannot be directly
integrated into traditional PGS
No need of precise
MPPT Algorithms for Partial Shading
Genetic Algorithm Can optimize parameters of other algorithms such as FLC
Its implementation is complex and difficult to achieve using
low cost microcontroller Current sweeping
method Fast tracking speed Requires periodical tracking of the MPP
Ant colony optimization
Fast convergence and convergence independent of the
initial condition
Implementation is difficult
Differential Evolution
Fast convergence and convergence independent of the
initial condition, easy to use
Some parameters may not guarantee optimal solution
Particle swarm optimization
Simpler structure than other EA techniques
Optimization performance depends on parameter
selection Chaos search
method
Improved search efficiency,
precision, and system robustness High complexity
Electrical PV array Reconfiguration
Compensate the power losses caused by PSC
Expensive and the controller design is also complex, fail to
track GMPP in some shading patterns
Solar PV- Challenges
4. Integration with Grid
Grid application
Many Issues with Grid integration.
1. Poor THD
2. Synchronization 3. Islanding Problem Hot areas of Research
Solar PV for Happy and Safe Future
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With a lot of investment in solar PV area by the world governments, it is going to be one of the major player in power industry.
As People are becoming more Conscious and
Concerned about environmental degradation, they are turning towards neat and cost effective solution to power requirement. In Germany, one can find
THANK YOU
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