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8/2/2019 Dr RK Bhogra Draft 2 Pres Solar 2010 Conf 21-22 Sep'10 DLI
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Solar Photovoltaics
by
OP Bhutani, Director (E, R&D), BHEL
Dr RK Bhogra, Consultant (Solar Energy), BHEL([email protected]; [email protected])
A talk on
SILICON TECHNOLOGIES: GIANT STRIDES
at the
Solar 2010
Conference
(21-22 Sep., 2010, New Delhi)
Organised byRenewable Energy India Forum (REIF)
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Solar Photovoltaics
04/26/12 BHEL ASSCP 2
Brief Business Scenario
PV industry experiencing an average annual growth rate of more than
45% during the last 5 years
Global Production-2001:0.4 GW, 2006:2.5 GW, 2009:12.3GW
Accelerated Growth Projected in future
Projected production plan-2010:21 GW (Earlier Proj was 15 GW)
Current share of Crystalline silicon solar cells: >80%
Mono crystalline ~ 34%
Multi crystalline ~ 47%
Global shortage of silicon feedstock being addressed by capacity additions
Thin film PV technologies(CdTe, CIGS, a-Si)
experiencing rapid development in view of possible technology break-
through leading to order-of-magnitude cost reduction, having current
average annual growth of thin film solar cells: over 80%
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Solar Photovoltaics
Source:Phot
onIntl.Mar10
155
202
287
401
560
750
1256
1815
2536 4
279 79
00
12300
21000
0
5000
10000
15000
20000
25000
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
MW
Year
Solar Cells Global ShipmentsActual & Projected
1998-2010
Actual
Projection
Year : 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010E
Growth %: -- 30 42 40 39 34 68 45 40 69 85 56 70E
+ 56%
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Solar Photovoltaics
04/26/12 BHEL ASSCP 4
PHOTOVOLTAICS MARKET GROWTH & FORECAST
Source:Photon International
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Solar Photovoltaics
Source: Photon International March10
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Solar Photovoltaics
04/26/12 BHEL ASSCP 6
PV TECHNOLOGY SHARE FORECAST
Forecast of PV Technology - Share
8576
31
1318
34
2 6
35
0
20
40
60
80
100
2010 2020 2030
Year
%ofShare
Crystalline
Thin FilmNew Technology
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Source:EPIA Solar Technology Roadmap 2008
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Source: Photon International Mar10
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Source: Photon International Feb10
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Global Strategy to tap PV businessTo maintain
the current
high growthrateof PV shipments &
to addressscarcity of siliconfeedstock,following three different pathways are beingpursued simultaneously:
1.Substantial increase in production of solar grade silicon
2.Reduction of material consumption through:-development of higher efficiency solar cells
-technology development for use of thinner wafers
3.Accelerated development and introduction of thin filmsolar cell technologies into the market.
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Photovoltaics (PV) is the science of direct conversion of light toD.C. electricity, based on the fundamental principle of
photovoltaic effect. This phenomenon is exhibited insemiconductor materials.
PV benefits from a number of attractive features:
Abundance of free fuel in the form of sunlight
No moving parts low maintenance
Totally noiseless, pollution free, benign source of energy
However, it also suffers from a few limitations:
Low energy density
Requires storage in batteries
Produces D.C. electricity that needs to be converted toA.C.
for many applications
Photovoltaics ?
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Solar spectral distribution
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Solar Photovoltaics04/26/12 BHEL ASSCP 13
Various materials(wrt electrical conductivity)
Conductors
Aluminium Al (13) (2,8,3)
Copper Cu (29) (2,8,18,1)
Silver Ag (47) (2,8,18,18,1)
Gold Au (79)(2,8,18,32,18,1)
Insulators
(Normally compounds like SF6,SiO2 and other ceramics, etc.)
Sulphur S (16) (2,8,6)
Selenium Se (34) (2,8,18,6)
Semiconductors
Silicon Si (14) (2,8,4)
Germanium Ge (32) (2,8,18,4)
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Solar Photovoltaics04/26/12 BHEL ASSCP 14
Crystalline structure
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Micro Crystalline structure
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Amorphous structure
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Solar Photovoltaics04/26/12 BHEL ASSCP 17
ConductionBand
BandGap
FreeElectron
e
Photon
~1.1eV
ValanceBand
Fig: BandGap- Energy levels ina crystal
What is band gap in a semiconductor?
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Solar Photovoltaics04/26/12 BHEL ASSCP 18
Theoretical efficiency limits of single junction solar cellsmade out of various semiconductors
Energy Band Gaps in solar cell materials
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Solar cells, the heart of a PV system, are meant to absorb
sunlight and convert it directly to electricity. These are madefrom a wide range of semiconductor materials.
For best solar energy conversion the optimum band gap is ~1.4 - 1.5 eV.
Some of the best solar cell materials are: Silicon (1.12 eV),InP (1.40 eV), GaAs (1.42 eV), CdTe (~1.44 eV) and CuInSe2(~1.0 eV).
Energy of the incident photons produce electron-hole pairs
that are separated by the electric field and give rise tounidirectional electric current.
These are collected by the external contacts at the two facesof the semiconductor and produce usable DC power.
Physics of solar cells
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Solar Photovoltaics04/26/12 BHEL ASSCP 20
Types of silicon used for making solar cells
Type of Silicon Abbreviation Crystal Size Range Method for
Production
Single-crystalsilicon
c-Si >10cm Crystal growth byCzochralski (CZ),Float zone (FZ)
Multicrystallinesilicon mc-Si 1mm-10cm Cast : Sheet &ribbon
Micro crystallinesilicon
c-Si 0.1 m 1 m Plasma EnhancedChemical-vapordeposition (PECVD)
Nano crystallinesilicon
nc-Si
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Solar Photovoltaics04/26/12 BHEL ASSCP 21
n-type semiconductors
(doping with Phosphorous)
p-type semiconductors
(doping with Boron)
Silicon Doping (n-type & p-type)
Physics of solar cells
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Basic principle of operation of a solar cell
Physics of solar cells
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Ways to maximize solar cell efficiency
Maximize absorption of light andconduction of photo carriers
Minimize reflection of light andrecombination of photo carriers
Physics of solar cells
Types of solar cells
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Crystalline silicon solar cells: mono crystalline silicon (c-
Si) and multicrystalline silicon (mc-Si)
Surface barrier solar cells (a-Si on c-Si) PassivatedInterface (PI) at hetero junction
Thin film solar cells:
amorphous silicon (a-Si)
polycrystalline copper indium diselenide (CIS) or
copper-indium-gallium - selenide / sulphide (CIGS)
cadmium telluride (CdTe)
thin-film crystalline silicon
Gallium arsenide (GaAs) and multi junction cells (GaInP /GaAs / Ge ) with super-high efficiency
Nano crystalline Dye-sensitized TiO2 based and other nano-structured solar cells
Organic (Polymer) solar cells
Types of solar cells based on choice of semiconductormaterial and device structure
Types of solar cells
M lti j ti l ll
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Multi junction solar cell structures based on crystallinethin films of compound semiconductors
Multi junction solar cells
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Comparison of cell and module efficiencies for various PV technologies
Efficiency comparision of various types solar cells
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Of all semiconductors materials, silicon has beenthe most popular choice for solar cells because ofits
-Availability in abundance
- Strong technological backup from electronics
industry
- Non-toxic and stable nature
- Less complex process for solar cell production
Silicon the most preferred PV material
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Sand to silicon wafers
Silane (used for a-Si)
(Poly Si Nuggets)
Poly silicon Manufacturing and supply chain
PV Technology
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Solar Photovoltaics04/26/12 BHEL ASSCP 29
Poly silicon Manufacturing and supply chainPV Technology
M /M l i lli ili f / ll
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Solar Photovoltaics04/26/12 BHEL ASSCP 30
Mono/Multi crystalline silicon wafers/cells
Mono crystalline Si wafer
Multi crystalline (mc-Si) ingot
Mono crystalline Si solar cell
Multi crystalline Si wafer Multi crystalline Si solar cell
~ 2x2x1 Si block
Mono crystalline Si Ingot
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Process flow chart
Silicon wafer
Wafercleaning
Texturisation Diffusion
Printing ofcontacts
Firing ofcontacts
Modulingand framing
Cell testing
AR coating Edgeisolation
Solar Cell
PV Technology
National Solar Mission R&D targets
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Solar Photovoltaics
National Solar Mission R&D targets
Crystalline Si (laboratory) (small area)
Mono Si (Production)
Multi Si (Production)
a-Si single/multi jn.(laboratory)
a-Si single/multi jn.(Productio Stabilizeda-Si/mc or nc Si tandem (laboratory)
a-Si/mc or nc Si tandem (production)
CIGS (laboratory)
CIGS (production)
CdTe (laboratory)
CdTe (production)
New materials (Dyes/Organic cells) labNew materials (Dyes/Organic cells) prodn.
Concentrator cells
GaAs (laboratory)
GaAs (production)
Silicon (laboratory)
Silicon (production)
Module life (years)Inverter
Efficiency
Life
Storage Battery
Efficiency (Wh)
Cycle life
Module cost (Rs./W)
22% 23.50% 25%
16-18 % 17-19 % 18-21 %
17-19 % 18-22 % 20-24 %
13.5% 14.5% 14.5%
7- 8 % 8-9.5 % 9-11 %12% 16% 20%
9% 12-14% 15-18%
15% 20% 25%
8-10% 12-15% 17-20%
15% 20% 25%
8-10% 12-15% 17-20%
5-10% 15% 25%8-10% 12-17%
27% 40% 45%
35% 40%
25% 28% 30%
30
>10 yrs.
2200-2800
>25 >30 >35
97%
1500-1800 1800-2200
25%
88% 90%
98% 98%
28%
100 60
>15 yrs. >20 yrs.
87%
Ph 1 (2010-13) Ph 2 (2013-17) Ph 3 (2017-22)
Indian PV scenario general facts
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Solar Photovoltaics
Indian PV scenario general facts
Total installed power generation capacity: 162 GW
RE power generation capacity:16.8 GW ^ (~ 10 % of total)
Cumulative PV installation: ~ 800 MW * (till 2009)
Total grid connected PV installation (power plants): ~ 6 MW *
Total off-grid PV installation (power plants & street lights):100 MW **
11th five-year plan target (PV+CSP): 1000 MW by 2011-12 as per NSM
guidelines announced on July 25, 2010; cumulative target of ~10,000 MW by 2022)
No. of cell manufacturers: 14(Annual capacity ~ 500 MW) &
No. of module manufacturers: 20 (Annual capacity ~ 1000 MW) *
No. of system integrators: ~ 50 *
Source: ^ Power Min. Website ; * ISA report on solar PV industry in India, May 2010 &
** EAI Solar PV Report, July 2010;&
CMG / BHEL, Aug 2010
Indian PV scenario cell & module production
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Solar Photovoltaics
n an V sc nar o c & mo u pro uct on
Production for the year 2009-10: Cell: ~ 240 MW &Module: ~ 300 MW&
Expected production capacity by the end of 2010:Cell ~ 750 MW *Module ~ 1250 MW *
& Verbal communication with MNRE, 19 Aug 2010* ISA report on solar PV industry in India, May 2010
Indian PV scenario cost projections for solar PV
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Solar Photovoltaics
p j f
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Solar Photovoltaics04/26/12 BHEL ASSCP 36
Extensive R&D being pursued globally to enhanceefficiencies (Target of 22-26%) of Crystalline Silicon solar cells:
-Hetero Junction Solar Cells (Sanyo)
- Rear Contact Solar cells (Sun Power)
- Laser Fired Contact Solar Cells
- Plasma based Reactive Ion Etching for Texturisation of
Multi-Crystalline Silicon (m-cSi) Solar Cells
- Selective Emitter Technology
- Silicon Ribbon Solar Cells
New Technologies under development
(Silicon based)
High efficiency Passivated Interface Hetero Junction solar cells
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Solar Photovoltaics
High efficiency Passivated Interface Hetero Junction solar cells
High Efficiency c-Si Solar Cell Passivated Interface Hetero-junction/ HIT Solar Cell
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Solar Photovoltaics
Passivated Interface Hetero-junction Solar Cell
Front Rear
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Solar Photovoltaics
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Solar Photovoltaics
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Solar Photovoltaics
Major issues in Solar Photovoltaics
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Major issues in Solar Photovoltaics
Availability & Price Stability of solar gradepoly silicon / wafers
High initial capital cost of Solar PV power
plants Fluctuating global political commitment &government support
Lack of Qualified/ trained manpower
Lack of service after sales infrastructure Lack of serious concern towardsenvironment
Solar Photovoltaics
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