1. Solar PV Technologies Basics and Current Status
CMIA Energy Conclave, 2013
Solar PV Technologies Basics and Current Status
Chetan S. Solanki
Department of Energy Science and Engineering
IIT Bombay
Indian Institute of Technology Bombay
3/25/2017
National Center for Photovoltaic Research and Education (NCPRE)

2. Commonly used semiconductors for solar cellsII
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, InGaAlP
3/25/2017
National Center for Photovoltaic Research and Education (NCPRE)

3. P-N Jn –separation force
Solar Cell Operation
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
P-N Jn –separation force
Metal contact
Different solar cell technologies strives to maximize the efficiency of the above three operations in different way

4. C-Si solar cell technologies
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 available
3/25/ © IIT Bombay, C.S. Solanki
National Center for Photovoltaic Research and Education (NCPRE)

5. Thin film solar cell technologies
Thin film Solar Cells
Silicon Based
Non Silicon Based
Amorphous Silicon
Other thin film
CdTe
CIGS
Organic/DSC
Flexible
Rigid
Companies
Substrate
Absorber Layer
Material Type
Unisolar, Flexcell
Kaneka, Sharp, EPV
Innovalight
CSG Solar, Nanogram
First Solar, AVA Tech
Nanosolar, Global Solar, Miasole
Wuerth Solar, Honda, Showa Shell
G24i, Konarka
3/25/2017
National Center for Photovoltaic Research and Education (NCPRE)

6. Types of cell junction Eg: c-Si cell
Junction is required to facilitate charge separation for PV operation
Homo-junction
P-i-N junction
N-type
P-type
Eg: c-Si cell
N-type
P-type
Intrinsic, i, layer
Eg: a-Si:H cells
Multi-junction
Cell 1, Eg1
Cell 2, Eg2
Cell 3, Eg3
Eg1 > Eg2 > Eg3
Hetro-junction
N-type
P-type
Eg: CdTe, CIGS cell
3/25/ © IIT Bombay, C.S. Solanki
Eg: GaAs, a-Si cells
National Center for Photovoltaic Research and Education (NCPRE)

7. Production of Mono C-Si wafers
Metallurgical grade Si (MGS)
Initial
Reaction
Cholorosilanes
Separation and purification
Pure SiHCl3
Deposit solid Si H2
Pure poly -EGS
EGS ingot
Grow single crystal
Si wafers
HCl
Solid
Gas
Liquid
Quarzite
Coal +
Melting
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

8. Production Multi-cSi Wafers
Blocks can be manufactured easily in square shape  Fits well in modules
Low eff. of multi-crystalline material disappears at module level
3/25/ © IIT Bombay, C.S. Solanki

9. Difference in manufacturing
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
3/25/ © IIT Bombay, C.S. Solanki
National Center for Photovoltaic Research and Education (NCPRE)

10. Generic industrial mc-Si Cell Process
Wafer Cutting
Standard process
Wet Acidic Isotropic texturing
POCl3 Diffusion
Parasitic Junction Removal
PECVD SiNx:H ARC layer
Screen Printed Metallisation
Dry processes, plasma etching are used for front texturing, emitter formation, are being employed to avoide wet chemical disposal and to avoid the large use of DI water.
Co-firing
Solar cell performance: %

11. Generic process for thin film Cell
(a) Glass substrate with TCO
Glass substrate
(b) Laser cut in TCO layer
TCO
Monolithic interconnection of cells in modules
Laser cuts are used to define cell area
Absorber layer
(c) Deposition of absorber layer
Back metal
(d) Laser cut in absorber layer
EVA
(e) Deposition of back metal contact
(f) Laser cut through metal and absorber layer
(g) Encapsulation with EVA
EVA
3/25/ © IIT Bombay, C.S. Solanki
National Center for Photovoltaic Research and Education (NCPRE)

12. Efficiency and Cost I Isc Pm ImVm Im Pm X
Voc
Power
Efficiency is defined as the ratio of energy output from the solar cell to input energy from the sun.
Raw material cost, cell and module processing
Production cost
Efficiency
Quality of material, technology understanding, cell size
Chetan S Solanki, IIT Bombay ITM Expo, 7th March, 2009

13. PV module product and cost
The annual production in 2012 was over 30,000 MW
The cost per Watt has come down to almost 1 $/Wp level
© Education Park, 2012

14. Global Annual PV Installation by technology
C-Si solar cell technology is dominant since its inception
Thin film technologies likely to improve their share

15. MW range solutions 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 © Education Park, 2012

16. kW range solutions 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. Few W range solutions 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 © Education Park, 2012

18. 100s of mW range solutions 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 © Education Park, 2012

19. National Centre for Photovoltaic Research and Education (NCPRE)
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
Education
Research
Si Solar Cells
New Materials & Devices
Solar PV Systems & Modules
Characterization, Modeling & Simulation

20. Facilities at NCPRE 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

21. 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
India was 5th largest country with presentation IEEE PV conf.
Base line cell process is being developed

22. Thank you for your attention
Solar Photovoltaic Technology and Systems
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