CMIA Energy Conclave, 2013
Indian Institute of Technology Bombay
4/9/2015
National Center for Photovoltaic Research and Education (NCPRE)1
II
III
B
IV
C(6)
V
VI
Al
Si(14)
P
S
Zn
Ga
Ge(32)
As
Se
Cd
In
Sb
Te
Elemental semiconductors: Si, Ge
Compound semiconductors: GaAs, InP, CdTe
 Ternary semiconductors: AlGaAs, HgCdTe, CIS
 Quaternary semiconductors: CIGS, InGaAsP, InGaAlP
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4/9/2015
National Center for Photovoltaic Research and Education (NCPRE)
2
 A solar cell should convert light into electricity with high efficiency
Metal contact
It requires
- Absorption of a photon
- Separation of a electron-hole pair
P-N Jn –separation force
Metal contact
- Collection of the charges at electrodes
 Different solar cell technologies strives to maximize the efficiency of the
above three operations in different way
3
Material Type
Monocrystalline
c-Si Solar
Cells
Multi
Crystalline
Companies
Sanyo,
SunPower,
SunTech, Trina,
Sharp, Kyocera
Csun, Qcells,
Trina,
Canadian
Solar, Sharp,
Kyocera
Ribbon Si
EverGreen
All these technologies are commercially available
4/9/2015
© IIT Bombay, C.S. Solanki
National Center for Photovoltaic Research and Education (NCPRE)
4
Material Type
Absorber Layer
Amorphous
Silicon
Substrate
Companies
Flexible
Unisolar,
Flexcell
Rigid
Kaneka, Sharp,
EPV
Flexible
Innovalight
Rigid
CSG Solar,
Nanogram
Rigid
First Solar, AVA
Tech
Flexible
Nanosolar,
Global Solar,
Miasole
Rigid
Wuerth Solar,
Honda, Showa
Shell
Silicon Based
Other thin film
Thin film
Solar Cells
CdTe
Non Silicon
Based
4/9/2015
CIGS
Organic/DSC
Flexible
G24i, Konarka
National Center for Photovoltaic Research and Education (NCPRE)
5
Junction is required to facilitate charge separation for PV operation
 Homo-junction
P-type
N-type
 P-i-N junction
P-type
Intrinsic, i, layer
N-type
Eg: c-Si cell
Eg: a-Si:H cells
 Multi-junction
 Hetro-junction
Eg1 > Eg2 > Eg3
Cell 1, Eg1
P-type
Cell 2, Eg2
N-type
Cell 3, Eg3
Eg: CdTe, CIGS cell
4/9/2015
© IIT Bombay, C.S. Solanki
Eg: GaAs, a-Si cells
6
Solid
Solid
Liquid
Metallurgic
al grade Si
(MGS)
Melting
Coal
+
Quarzite
H2
Cholorosilanes
Separation
and
purification
Gas
Pure SiHCl3
Grow
single
crystal
EGS ingot
Solid
Liquid
Si wafers
Size of the c-Si cell is determined by the size of the ingot
 Shape of the c-Si is determined
by the shape of ingot
7
Deposi
t solid
Si
Solid
poly-EGS
Purepoly
-EGS
Pure
Gas
HCl
Initial
Reaction
4/9/2015
 Blocks can be manufactured easily in square shape  Fits well in modules
 Low eff. of multi-crystalline material disappears at module level
© IIT Bombay, C.S. Solanki
8
 Mono-crystalline and Multi-crystalline Si substrates are grown
 The substrate acts as absorber (of light) material
 In thin film solar cells, the absorber layer is deposited
 Since the films are thin, a supporting substrate is required
Starting Wafer
c-Si process
4/9/2015
© IIT Bombay, C.S. Solanki
Supporting substrate
Thin film process
National Center for Photovoltaic Research and Education (NCPRE)
9
Wafer Cutting
Standard process
Wet Acidic Isotropic texturing
POCl3 Diffusion
Parasitic Junction Removal
PECVD SiNx:H ARC layer
Screen Printed Metallisation
Co-firing
Solar cell performance:
12 - 16%
(a) Glass substrate with TCO
Glass
substrate
(b) Laser cut in TCO layer
TCO
Absorber
layer
Back
metal
EVA
(c) Deposition of absorber layer
(d) Laser cut in absorber
layer
Monolithic interconnection of
cells in modules
Laser cuts are used to define
cell area
(e) Deposition of back metal
contact
(f) Laser cut through metal and
absorber layer
(g) Encapsulation with EVA
EVA
4/9/2015
© IIT Bombay, C.S. Solanki
National Center for Photovoltaic Research and Education (NCPRE)
11
I
Isc
Pm
Im
X
Vm Voc
$
2
$
m
Cost 


Watt Watt 2
m
Chetan S Solanki, IIT Bombay
• Efficiency is defined as the ratio of
energy output from the solar cell to
input energy from the sun.
Voc I sc FF
Efficiency  
Pin
Raw material cost, cell
and module processing
Production cost
Efficiency
Quality of material, technology
understanding, cell size
ITM Expo, 7th March, 2009
12
35000
4.44
30000
4.4
31518.4
3.79
3.39
3.8
25000
PV Production
(MWp)
3.82
3.25
2.75
20000
2.65
15000
23579.3
3.5
2.9
3.03
17402.3
2.65
2.18
1.48
10000
1.37
7913.3
5491.8
5000
82.6
134.8
252
504.9
1407.7
1049.8
1984.6
0.98
3073
0
1994 1996 1998 2000 2002 2004 2006 2008 2010
2012
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Average Selling
Price (US$)
PV module product and cost
2014
Year
The annual production in 2012 was over 30,000 MW
The cost per Watt has come down to almost 1 $/Wp level
Chetan
S Solanki
© Education
Park, 2012
13
C-Si solar cell technology is dominant since its inception
 Thin film technologies likely to improve their share
Typical PV Wattage
1 MW to 100 MW
Electricity generated
4000 kWh to 40,000 kWh per day
1.5 Million units to 150 Million unit per year
Where it can be used?
Powering the grid, captive power plants,
supplying peak load
Barrier for large scale
implementation
Initial high cost, lack of bank funding
Suitability of grid, appropriate arrangement to
sell electricity to govt.
Chetan S Solanki
15
Typical PV Wattage
1 kW to 100 kW
Electricity generated
4 kWh to 400 kWh per day
1500 unit to 150,000 unit per year
Where it can be used?
Household electricity needs, industrial electricity,
water pumping, academic campuses
Barrier for large scale
implementation
Initial high cost, lack of awareness about Govt.
policies, Bankers lack of awareness,
Availability of product, local services
Chetan S Solanki
16
Typical PV Wattage
1 W to 10 W
Electricity generated
4 Wh to 40 Wh per day
1.5 unit to 15 unit per year
Where it can be used?
Solar lamps, home lighting system, mobile
charger
Barrier for large scale
implementation
Initial high cost, lack of awareness
Availability of product, local services
Chetan S Solanki
17
Typical PV Wattage
10mW to 1000 mW
Electricity generated
40 mWh to 4 Wh per day
0.01 unit to 1.5 unit per year
Where it can be used?
Calculators, toys, mobile charger A study solar
lamp
Barrier for large scale
implementation
No issue with calculators, toys
Solar study lamp - Availability of product, local
services
Chetan S Solanki
18
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

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JNNSM launched in January 2010
NCPRE set up in October 2010 by MNRE as part of JNNSM
5 year Project
Strong Education + Research thrust
NCPRE
www.ncpre.iitb.in
Education
Si Solar Cells
Research
New
Materials &
Devices
Characterization,
Modeling &
Simulation
Solar PV
Systems &
Modules
C-Si Lab Facilities
Plasma Enhanced CVD (PECVD)
Edge Isolation Tool
Diffusion Furnace
Quantum Efficiency Measurement System
Screen Printer
UV-Vis-NIR spectrometer
Corescan
 Laser Doping System
Four Probe System
Carrier Lifetime Tester
RTP system
Solar IV characterization System
c-Si Solar Cell Fab Lab
 Full fledged crystalline silicon solar cell fab pilot line of area
1800 sq feet was commissioned as part of NCPRE
Base line cell process
is being developed
Solar
Photovoltaics
Fundamentals,
Technologies
and Applications
Second Edition
Chetan Singh
Solanki
SOLAR
PHOTOVOLTAICS
A LAB TRAINING
MANUAL
Chetan S Solanki
Brij M Arora
Juzer Vasi
Mahesh B Patil
Solar Photovoltaic
Technology and
Systems
A manual for
Techicians, Trainers and
Engineers
Chetan Singh Solanki