WaferWafer--based silicon PV technologybased silicon PV … · 2017-09-29 · WaferWafer--based...
Transcript of WaferWafer--based silicon PV technologybased silicon PV … · 2017-09-29 · WaferWafer--based...
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WaferWafer--based silicon PV technologybased silicon PV technologyStatus, innovations and outlookStatus, innovations and outlook
Wim Sinke
ECN Solar Energy, Utrecht University & European PV Technology Platform
Contents
• Wafer-based silicon photovoltaics
- features
- market position
- history and state-of-the-art
• Cell and module efficiencies
- achievements so far
- limiting factors
- options for further improvement
• Towards integration of cell and module designs
• Cost reduction potential
• Outlook
Contents
• Wafer-based silicon photovoltaics
- features
- market position
- history and state-of-the-art
• Cell and module efficiencies
- achievements so far
- limiting factors
- options for further improvement
• Towards integration of cell and module designs
• Cost reduction potential
• Outlook
Wafer-based crystalline silicon
- ½ century of manufacturing experience
- huge technology base (materials, processes & device designs)
- extensive track record (performance, lifetime & reliability
- highest performance of flat-plate technologies
- further cost reduction (preserving efficiency) is main overall challenge
Bell
Cell & module technologies (“flat plate”)Commercial: wafer-basedcrystalline silicon- monocrystalline (cut)- multicrystalline (cut)- ribbons(80% of global market)
Commercial: thin films- silicon- copper-indium/gallium-diselenide (CIGS)- cadmium telluride (CdTe)(20% of global market)
Pilot production and laboratory:emerging and novel technologies- super-low-cost concepts
(printed organic & inorganic, etc.)- super-high-efficiency conceptsECN/Holst Centre
ECN
Nanosolar
Helianthos
Cell & module technologies (“flat plate”)
Commercial: wafer-basedcrystalline silicon
module efficiencies 13 ~ 19%
Commercial: thin films
module efficiencies 6 ~ 12%
Pilot production and laboratory:emerging and novel technologies
(various efficiencies;most not yet commercially available)ECN/Holst Centre
ECN
Nanosolar
Helianthos
The silicon PV value chain
Siliconfeedstock
Crystal WaferSolarcell
Solarmodule
PV-system
Solarelectricity
Typical current industrial silicon solar cell
• B-doped substrate (base)• P-doped front (emitter)• Al-doped rear (back surface field, BSF)
• SiN anti-reflection coating / passivation layer• Ag contacts
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Cell design options
Standard:front emitter
Rear emitter / frontsurface field
Heterojunction
Metallisation WrapThrough (MWT)
Emitter Wrap Through(EWT)
Back Junction BackContact (BJBC)
Carrier collection at front
Carrier collection at rear
Front and rear contacted
All rear contacted
SunPower
Sanyo
Passivated Emitter and Rear Locally diffused (PERL) cell
Zhao, Wang & Green, UNSW (1999)
World record monocrystalline silicon cell(efficiency 25.0%)
based on Interdigitated Back Junction, Back Contact cells
Courtesy SunPower Corp.
World record monocrystalline silicon large-areamodule (efficiency 21.4%)
ancestor (1986):Point Contact Solar Cell
(>28% under concentration)
Swanson, Sinton & King
based on HIT (Heterojunction with Intrinsic Thin layer) cells
Courtesy Sanyo Electric Co., Ltd.
Very high efficiency monocrystalline siliconlarge-area module (efficiency …%)
Contents
• Wafer-based silicon photovoltaics
- features
- market position
- history and state-of-the-art
• Cell and module efficiencies
- achievements so far
- limiting factors
- options for further improvement
• Towards integration of cell and module designs
• Cost reduction potential
• Outlook
Historic efficiency development crystallinesilicon cells and modules (rounded values)
0
5
10
15
20
25
301
95
0
19
55
19
60
19
65
19
70
19
75
19
80
19
85
19
90
19
95
20
00
20
05
20
10
20
15
Eff
icie
nc
y[%
]
Year
best laboratory cell(multicrystalline Si)
best laboratory cells(monocrystaline Si)
typical commercial modules
Photovoltaic conversion:basic process and losses
energy gap(Si: 1.12 eV)
generation
recombination
X
X
X
Solar spectrum and spectral losses
wavelength [nm]
1.6
1.2
0.8
0.4
400 800 1200 1600 2000 24000.0
available for conversion in crystalline Si
infraredvisibleUV
solar spectrum (Air Mass 1,5; 1000 W/m2)
po
we
r[W
/(m
2.n
m)]
1100 nm 1.1 eV = Si bandgap
courtesy John Schermer, KUNCourtesy John Schermer, RUN, NL
X
X
Solar cell electrical characteristic:voltage and curve factor losses
LkTqV
0 J1eJJ
cu
r re
nt
Pmax
Vmax
Imax
voltage
cu
r re
nt
Pmax
Vmax
Imax
voltage
gapL E
J
J
q
kT
1lnV
0
OC
1max
P
JVFF
scoc
light
scoc
P
FFJV
Jmax
Crystalline silicon solar cell conversionefficiencies: limits and losses (indicative)
From lab to fab
• Trade-off between cost & performance
• Small area large area
• Best average
• Lower Si material quality, highly doped regions, surfacesand contacts additional recombination: Jsc, Voc
• Additional optical losses (reflection & transmission): Jsc
• Additional resistive losses: FF
• Efficiency range multicrystalline Si cells: ~14-17%
• Efficiency range monocrystalline Si cells : ~16-22%
Selected options for further improvement
• Minimize recombination:
- improve material quality manage defects and impurities, usen-type Si
- reduce heavy doping effects local doping, selective emitters
- effective surface passivation SiNx, SiO2, Al2O3, aSi, etc.
- low-recombination contacts heterojunctions
• Minimize optical losses
- reduce reflection, apply light trapping coatings & textures,plasmonic structures?
- reduce shadow losses rear contact designs
• Minimize resistive losses
- increase conductance advanced electrode architectures andmaterials, rear contact designs
Example:understanding and managing impurities
Understanding and managing impurities:effects of Fe, Ni, Cr added to Si feedstock
Bottom Middle Top
8
10
12
14
16
0% 20% 40% 60% 80% 100%Position in the ingot [%]
Eff
icie
ncy
[%]
Ref
Fe 50 ppm wt
Cr 40 ppm wt
Ni 40 ppm wt
Fe 200 ppm wt
• Major metal impurities positively charged in p-type, neutral in n-type.
• p-type dopant B forms B-O recombination center
Understanding and managing impurities:replace p-type Si by n-type Si
n-type siliconsubstrate
(n+) Phosphorus BSF
(p+) Boron emitter
Feo/+
Tio/+
p-type siliconsubstrate
(n+) Phosphorous emitter
Fe+/o
Ti+/o
Back contact
B-O2i
Example: the importance of low-recombinationcontacts
• Well-passivated emitter: ~30 fA/cm2 or less
• Ohmic contacts: ~1000-2000 fA/cm2
• With only 5% contact coverage, 50-100 fA/cm2 from contacts
1lnV
00OC
be
L
JJ
J
q
kT
passcontconteconte JfJfJ ,0,00 )1(
25 12-10-2010
Low-recombination contacts
• Transfer majority carriers without (resistive) loss
• Reflect minority carriers without recombination loss
“minority carrier mirrors”
• Practical solution:
- silicon heterojunction contacts
Graph: Miro Zeman, DUT, NL, 2010
Example: apply light trapping
• Full absorption (even) in very thin substrates
low bulk recombination (high Voc) combined with high Jsc
allow the use of low-quality materials
plasmon pictures Amolf
27 12-10-2010
Example: The best of both worlds (SunPower &Sanyo) – the IBC-HIT cell
• No shadow losses on front
• No optical absorption losses on front
• Very low contact recombination at rear (beyond aSi)
Work incollaboration withUniv. Rome, ENEA,ECN, Univ. Utrecht,and othersM. Tucci et al., “BEHIND” cell concept
Contents
• Wafer-based silicon photovoltaics
- features
- market position
- history and state-of-the-art
• Cell and module efficiencies
- achievements so far
- limiting factors
- options for further improvement
• Towards integration of cell and module designs
• Cost reduction potential
• Outlook
Anatomy of a standard module
• Module consists of:
- glass superstrate
- encapsulant (EVA)
- interconnected solar cells
- encapsulant (EVA)
- rear-side foil
• Finishing:
- framing
- junction box
- cabling and wiring
Base: pn+
Base: pn+
Base: pn+
Base: pn+
Base: pn+
A A
Cross-section AA
Example: Metallisation Wrap-Through (MWT)cell
inspired by Surface-Mount Technology (SMT)
Photo: GEC, Inc.
MWT cells & module:“single-shot” module manufacturing
Section of conductive foil
Rear of cell
Design and manufacture of MWT module
Equipment by Eurotron (NL)
Technology- 120 µm (Deutsche Solar)
and 160 µm (REC) mc-Si wafers
- Conductive adhesive (alternative: low-T solder)
- Patterned rear-side foil
- Novel module line; zero cell breakage
Module results- Aperture area efficiency:
- 16.0 % (120 µm cells)
- 17.0 % (160 µm; 17.8% cells)
MWT cells and modules
Contents
• Wafer-based silicon photovoltaics
- features
- market position
- history and state-of-the-art
• Cell and module efficiencies
- achievements so far
- limiting factors
- options for further improvement
• Towards integration of cell and module designs
• Cost reduction potential
• Outlook
How far can wafer Si module cost go down?
• h
36 12-10-2010
Cost structure of wafer Si PV (2009)
From Peter Fath, Centrotherm, 2009
Contents
• Wafer-based silicon photovoltaics
- features
- market position
- history and state-of-the-art
• Cell and module efficiencies
- achievements so far
- limiting factors
- options for further improvement
• Towards integration of cell and module designs
• Cost reduction potential
• Outlook
Crystalline silicon: first generation PV?
• picture
Mariska de Wild-Scholten, Environmental Sustainability of Thin Film PV2nd EPIA International Thin Film Conference, 12 November 2009, Munich
Energy payEnergy pay--back time of turnback time of turn--key PV systemskey PV systems
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Carbon footprint of selected electricity generatingCarbon footprint of selected electricity generatingtechnologiestechnologies
Mariska de Wild-Scholten, Environmental Sustainability of Thin Film PV2nd EPIA International Thin Film Conference, 12 November 2009, Munich
9 March2010
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©Greenpeace