dr rk bhogra draft 2 pres solar 2010 conf 21-22 sep'10 dli

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

([email protected])&

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


PHOTOVOLTAICS MARKET GROWTH & FORECAST

Source:Photon International


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Solar Photovoltaics

Source: Photon International March10


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Solar Photovoltaics


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



Source: Photon International Mar10



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.



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 ?



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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Crystalline structure


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Micro Crystalline structure


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Amorphous structure


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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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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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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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n-type semiconductors

(doping with Phosphorous)

p-type semiconductors

(doping with Boron)

Silicon Doping (n-type & p-type)



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Basic principle of operation of a solar cell



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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


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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Poly silicon Manufacturing and supply chainPV Technology

M /M l i lli ili f / ll


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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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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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dr rk bhogra draft 2 pres solar 2010 conf 21-22 sep'10 dli

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