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04/10/23 1
National Center for Photovoltaic Research and Education (NCPRE)
Indian Institute of Technology Bombay
CMIA Energy Conclave, 2013
2
II III IV V VI
B C(6)
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,
InGaAlP04/10/23National Center for Photovoltaic Research and Education (NCPRE)
3
A solar cell should convert light into electricity with high efficiency
It requires
- Absorption of a photon
- Separation of a electron-hole pair
- Collection of the charges at electrodes
Different solar cell technologies strives to maximize the efficiency of the above three operations in different way
P-N Jn –separation force
Metal contact
Metal contact
c-Si Solar Cells
Mono-crystalline
Multi Crystalline
Companies
Material Type
Sanyo, SunPower, SunTech, Trina, Sharp, Kyocera
EverGreen
Csun, Qcells, Trina, Canadian Solar, Sharp, Kyocera
Ribbon Si
All these technologies are commercially available04/10/23 © IIT Bombay, C.S. Solanki 4National Center for Photovoltaic Research and Education (NCPRE)
Thin film Solar Cells
Silicon Based
Non Silicon Based
Amorphous Silicon
Other thin film
CdTe
CIGS
Organic/DSC
Flexible
Rigid
Flexible
Rigid
Rigid
Flexible
Rigid
Flexible
Companies
SubstrateAbsorber Layer
Material Type
Unisolar, Flexcell
Kaneka, Sharp, EPV
Innovalight
CSG Solar, Nanogram
First Solar, AVA Tech
Nanosolar, Global Solar, MiasoleWuerth Solar, Honda, Showa ShellG24i, Konarka04/10/23 5National Center for Photovoltaic Research and Education (NCPRE)
N-type
P-type
Eg: c-Si cell
N-type
P-type
Eg: CdTe, CIGS cell
Cell 1, Eg1
Cell 2, Eg2
Cell 3, Eg3
Eg1 > Eg2 > Eg3
N-type
P-type
Intrinsic, i, layer
Eg: a-Si:H cells
04/10/23 © IIT Bombay, C.S. Solanki 6
National Center for Photovoltaic Research and Education (NCPRE)
Homo-junction
Hetro-junction
P-i-N junction
Multi-junction
Junction is required to facilitate charge separation for PV operation
Eg: GaAs, a-Si cells
7
Metallurgical grade Si (MGS)
InitialReaction Cholorosilan
es
Separation and
purification
Pure SiHCl3
Deposit solid Si
H2
Pu
re p
oly
-EG
S
EGS ingot
Grow single crystal
Si wafers
HC
l
Solid
Gas Gas
Solid
Liquid
Solid
QuarziteCoal +Liquid
Melting
Solid
Pu
re p
oly
-EG
S
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
04/10/23 © IIT Bombay, C.S. Solanki 8
Blocks can be manufactured easily in square shape Fits well in modules Low eff. of multi-crystalline material disappears at module level
04/10/23 © IIT Bombay, C.S. Solanki National Center for Photovoltaic Research and Education (NCPRE) 9
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
Supporting substrate
Thin film process
Wafer Cutting
Wet Acidic Isotropic texturing
POCl3 Diffusion
Parasitic Junction Removal
PECVD SiNx:H ARC layer
Co-firing
Screen Printed Metallisation
Standard process
Solar cell performance: 12 - 16%
04/10/23 © IIT Bombay, C.S. Solanki National Center for Photovoltaic Research and Education (NCPRE) 11
EVA
Glass substrate
TCO
Absorber layer
Back metal
EVA
(a) Glass substrate with TCO
(b) Laser cut in TCO layer
(c) Deposition of absorber layer
(d) Laser cut in absorber layer
(e) Deposition of back metal contact
(f) Laser cut through metal and absorber layer
(g) Encapsulation with EVA
Monolithic interconnection of cells in modules
Laser cuts are used to define cell area
Chetan S Solanki, IIT Bombay ITM Expo, 7th March, 2009 12
in
scoc
P
FFIVEfficiency
• Efficiency is defined as the ratio of energy output from the solar cell to input energy from the sun.
IscI
Vm
Im
Pm
X
Voc
Power
2
2$
$
mWattm
WattCost
Production cost
Efficiency
Raw material cost, cell and module processing
Quality of material, technology understanding, cell size
Chetan S Solanki © Education Park, 2012 13
The annual production in 2012 was over 30,000 MWThe cost per Watt has come down to almost 1 $/Wp level
PV module product and cost
C-Si solar cell technology is dominant since its inception Thin film technologies likely to improve their share
Chetan S Solanki ©
Education Park, 2012
15
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 fundingSuitability of grid, appropriate arrangement to sell electricity to govt.
Chetan S Solanki ©
Education Park, 2012
16
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 ©
Education Park, 2012
17
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 awarenessAvailability of product, local services
Chetan S Solanki ©
Education Park, 2012
18
Typical PV Wattage 10mW to 1000 mW
Electricity generated 40 mWh to 4 Wh per day0.01 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, toysSolar study lamp - Availability of product, local services
JNNSM launched in January 2010 NCPRE set up in October 2010 by MNRE as part of JNNSM 5 year Project Strong Education + Research thrust
www.ncpre.iitb.in
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
ApplicationsSecond Edition
Chetan Singh Solanki
Solar Photovoltaic Technology and SystemsA manual for Techicians, Trainers and Engineers
Chetan Singh Solanki
SOLAR PHOTOVOLTAICSA LAB TRAINING MANUAL
Chetan S SolankiBrij M AroraJuzer VasiMahesh B Patil