The document provides information about solar cells and photovoltaic technology. It discusses how solar cells work using the photovoltaic effect to convert sunlight into electricity. It describes the basic components of solar cells including semiconductor materials like silicon, the p-n junction, and how sunlight generates electron-hole pairs that create voltage. It also outlines the characteristics and efficiency of solar cells as well as common types of solar cells used in photovoltaic modules and systems.

1. Presented By
Malik Sameeullah
NATIONAL INSTITUTE OF TECHNOLOGY,
KURUKSHETRA
1

2. Solar Cell
Photovoltaic (PV) Effect:
Electricity can be produced from sunlight through a
process called the PV effect, where “photo” refers to light
and “voltaic” to voltage.
Solar Cell
Solar cell is a device that converts the light energy into
electrical energy based on the principles of photovoltaic
effect.
2

3. Type of material: Based on
electrical conductivity
Electron energy
CB
CB
CB
overlap
Bandgap
VB
VB
metal
semiconductor
VB
insulator
Conduction band
Valance band
3

4. Choice of material
• Solar cell is composed of semiconductor material
• A typical silicon PV cell is composed of a thin
wafer consisting of an ultra-thin layer of
phosphorus-doped (N-type) silicon on top of a
thicker layer of boron-doped (P-type) silicon.
4

5. Solar Radiation: photon energy
 Solar energy is primarily transmitted to the Earth by
electromagnetic waves
 It can also be represented by particles (photons)
 Solar radiation consist of range of particles, classified
based on wavelength (frequency)
5

6. Region Of EM wave
Frequency
Energy
ultraviolet
100nm
1.2 keV
visible(blue)
400 nm
3.1 eV
visible(red)
700 nm
1.8 eV
infrared
10000 nm
0.12 eV
 Ultraviolet radiation is absorbed by ozone layer.
 So, solar radiation available to us have a photon energy
in between 0.1 eV to 4.4 eV
 That’s why semiconductor is used, whose band gap
energy is in between the range
 Insulator require photon of above 4.4 eV energy, so
solar radiation is not sufficient to knock electron from
valence band to conduction band
6

7. Fundamental of semiconductor
 Silicon and germanium are 4 group element use for





semiconductor device
Ideal semiconductor with no lattice defect and no
impurity is called an intrinsic semiconductor
Electron and holes are created in a semiconductor due
to the thermal excitation
For using it at particular temperature, impurities is
added
The process of impurity addition is called doping
The semiconductor in which impurity are added is
called extrinsic semiconductor
7

8.  P-type: A P-type material is one in which holes are
majority carriers i.e. they are positively charged
materials (++++)
 N-type: A N-type material is one in which electrons are
majority charge carriers i.e. they are negatively charged
materials (-----)
Fermi Level
It is the energy position within the band gap from where greater no of carriers
(holes in p type and electron in n type) get excited to become charge carrier.
For an intrinsic semiconductor , the fermi levels exists at the mid point of the
energy band.
8

9. P type semiconductor
Co-Valent
bonds
Si
N type semiconductor
Co-Valent
bonds
Hole
Si
In
B
Si
Si
electron
Si
Si
Si
Si
Impure atom
(donor)
Impure atom
(acceptor)
Conduction band
Electron
energy
E
Ec
Ec
Acceptor levels
Ev
Valence band
E
Eg
Ea
Electron
energy
Conduction band
Ec
Donor levels
Ec
Ed
Eg
Ev
Valence band
9

10. P-N Junction: building block for
solar cell
 To convert photon energy into electrical energy, there is
two basic requirement:
1. Increase in the potential energy of carriers (generation of
electron-hole pair)
2. Separation of carriers
 Semiconductor have energy band separated from each
other and may fulfill first requirement
 Separation of charge require asymmetry, so p-n diode
structure require.
 So, basic solar cell is a p-n diode with slightly variation in
design
10

11. P-N Junction I-V Relation
P-N junction under forward bias:
• The potential energy difference between the conduction
band at p-side and at n-side is reduced
• Majority electron diffusion current increases exponentially
with applied potential
• Minority electron drift current remain unaffected
P-N junction under reverse bias:
• Potential energy barrier height increase
• Diffusion current due to majority carrier becomes negligible
• Drift current magnitude remain as it is.
11

12. 12

13. P-N Junction as a solar cell:
Illumination condition
 When solar radiation absorbed in P-N diode,
electron hole pair generated.
 Minority carrier cross the junction as they move
from high energy to low energy side
 Minority electron from p side come to n side
 Minority hole from n side come to p side
 There is net increase in potential difference
 This generation of photovoltage is known as
photovoltaic effect.
 Minority carrier after generation travel average
length L (diffusion length) before die
 Minority charge generated within the distance L
from junction help in photovoltaic effect
radiation
Carrier
recombine
electron
P- type
N- type
hole
W
13

14. I-V equation of solar cell

I
Dark condition
V
Illumination
14

15. Solar Cell Characteristics

I
V
I-V curve of solar cell and its parameter
15

16. Short circuit current

Band gap (eV)
Short circuit current as a function of
band gap of semiconductor materials
16

17. Open Circuit Voltage

17

18. Fill Factor

18

19. Efficiency
 Short circuit current decreases with increase in band




gap
Open circuit voltage increases with increase in band
gap
There is optimum band gap for maximum efficiency
The maximum solar cell efficiency of about 31% is
obtained for the optimum band gap of about 1.45 Ev
The efficiency calculate at AM1.5 and for single
junction cell
19

20. Losses in Solar Cell
Losses in solar
cell
Fundamental
loss
Low energy
photon
Technical loss
Electrical
Optical
Excess energy
of photon
Voltage loss
Fill Factor loss
Reflection
shadowing
Non absorbed
Ohmic
recombination
20

21. Spectrum Loss
 Photon having energy less than band gap energy do not
absorbed
 There is a heat loss when photon having energy higher
than band gap energy
Loss of low energy photon=23%
Loss due to excess energy of photon=33%
Maximum efficiency possible if other loss neglected=46%
21

22. Voltage and Fill Factor Loss
 Actual open circuit voltage is less than band gap
voltage
 Voltage loss is due to unavoidable intrinsic Auger
recombination
 For ideal solar cell FF=1
 But in actual it value is equal to 0.89
 This type of loss arises from the parasitic resistance
(series and shunt) of the cell
22

23. Reflection and incomplete absorption loss
 A part of radiation reflected from the cell surface
 This loss is minimized by using anti-reflective coating
and surface texturing
 Some photon have enough energy to knock carriers
 But they are not absorbed because of limited thickness
of cell
23

24. Top metal coverage loss
 To collect current there is metal contact network on
top
 Loss due to contact shadow is about 8%
 This loss is reduce by using transparent contact
24

25. Minimization of Optical Loss
 Putting anti-reflection coating on the surface
 Texturing front surface
 Minimize the front metal contact coverage area
 Making solar cell thicker to increase absorption
Anti reflection
coating
Textured
surface
25

26. Elementary material used in solar cell
Groups of periodic table
2nd
3rd
4th
5th
6th
B
C
Al
Si
P
S
Zn
Ga
Ge
As
Se
Cd
In
Sb
Te
Typical semiconductor used in PV cell
Elemental
• Germanium
• Silicon
Binary Compound
•
•
•
•
Ternary Compound
Gallium arsenide
Indium arsenide
Cadmium sulfide
Cadmium telluride
• Aluminium gallium arsenide
26

27. Commercial Silicon solar cell

27

28. Photovoltaic generations
Solar cell divided into three main categories called
generations:
• 1st generation: Si wafer based technology
High cost and efficient
• 2nd generation: Amorphous silicon, CdTe etc.
Low cost and less efficient
• 3rd generation: Solar Paint, bio cells
Low cost and very efficient
28

29. 1st generation: Silicon wafer technology
2nd generation: Thin film based technology
3rd generation: Advanced nanostructure technology
29

30. ?
1st generation
2nd generation
Silicon module
Thin film module
3rd generation
Still in research
30

31. Various Type of silicon cell
 Monocrystalline silicon cell
1.
Silicon is grown in into a single crystal ingot
2.
Single crystal is in the form of cylindrical block
3.
Wafer of silicon is cut and used for solar cell
4.
So cell is of circular or Pseudo square type
• Polycrystalline silicon cell
1.
Grown in ribbon form
2.
There is no of crystal surface
3.
Chemical vapour deposition technique used
 Amorphous silicon cell
1.
There is no crystal property
2.
Less energy photon wasted as heat
3.
Multi junction of different band gap energy also used
31

32. Monocrystalline silicon cell
Polycrystalline silicon cell
Symmetry in
structure
Circular wafer
Pseudo wafer
Square wafer
Patches in the
structure
32

33. Commercial solar PV system
PV Module
PV Array
Cell
• No of cell in series
and parallel
combination
• Watt from 0- 1 kW
• No of module in series and
parallel
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34. Parameter of PV module

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35. Test condition of module

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36. PV solar panel specifications
Flexible Versions
•A variety of wiring and framing options
• are available upon request.
315 watt, 300 watt and 285
watt modules. Prices start are
$4.03/watt for cases of (20)
modules.
Independently Certified
* The ASE-270/DGF-50 is
independently certified to
meet IEEE 1262, IEC 61215
and UL 1703 standards
* It is also the only panel in
the industry to receive a UL
(Underwriters Laboratories)
Class A fire rating
Electrical Data
Power (max): 270 Watts
Voltage: 49.5 Volts
Current: 5.45 Amps
Open-circuit voltage: 60.0 Volts
Short-circuit Current: 6.1 Amps
Dimensions and Weights
Length: 74.5"/1892.3 mm
Width: 50.5"/1282.7 mm
Weight: 107 (+/- 5) lbs/46.6 (+/- 2) kg
Area: 26.13 ft sq/ 2.43 sq meters
Characteristic Data
Solar cells per panel: 216
Type of solar cell: Semi-crystalline solar cells (EFG process)
Connections: 10 AWG single conductor, stranded copper with MultiContact connector. Junction box comes with 6 built-in bypass
diodes.
Certifications and Warranty
The ASE-270-DGF/50 has been independently certified to IEC 1215
and IEEE 1262, UL 1703 (Class A Fire rating)
The ASE-270-DGF-50 comes with a 20 year power warranty.
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37. PV manufacturers

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Suntech Power
BP Solar
Tata BP
Moserbaer Solar
Mitbhushi Electric
GE Energy
First Solar
Sungen Solar
Bharat Electronics Limited
Kotak Urja
Sharp Solar
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38. Thank
You
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