1

xSi PV technologies roadmap

Overall coordination - TKI: Wim Sinke and Wijnand van Hooff

ECN: Ingrid Romijn, Jan Kroon, Bonna Newman and Arthur Weeber

2

Crystalline silicon learning curve

2004

2006 c-Si price increase

due to poly-Si shortage

2012 overproduction

in Asia

2016: 0.6 USD/Wp

Bell labs

PV-magazine / Active Solar

3

Why composing a roadmap?

• to steer and focus research and development activities

• to measure progress of the overall innovation program

• to benchmark status and progress to the international PV sector

in the end to facilitate the process of achieving the goals and ambitions of

the Dutch PV sector (NL PV sector)

4

Contents

• General goals of the Dutch PV sector

• Considerations for the roadmap

– Efficiency, costs, energy yield

Roadmap

• Innovation goals

• Research topics

• Examples of ongoing research

5

General goals and ambitions for NL PV sector

Sector goals and ambitions

(NB: indicative numbers still to be verified) Unit

Achieved Ambition for Potential

2015 2020 2030 2050

Total installed capacity of solar PV

systems in NLGWp 1,5 6 20 >100

Annual solar energy generated by PV

systems in NL

(total annual consumption is ≈100 TWh)

TWh 1,2 5 16 >80

Annual turnover of the Dutch PV sector Billion € 2 3 4 6

Annual export of the Dutch PV sector Billion € 0,2 1 2 3

Total employment in het Dutch PV sector FTE 10.000 15.000 20.000 30.000

6

Innovation is essential to achieve sector goals

NL PV sector goals and ambitions can be achieved through:

• Social innovations – make it easy and attractive for people to buy solar PV

• Business innovations – new business models to earn money with solar PV

• Technology innovations – cheaper, more efficient PV systems that look

great!

Technology innovations

• Wafer based crystalline silicon PV technologies (xSi PV)

• Thin films PV technologies (TF PV technologies)

• Hybrid tandem PV technologies (combines the first two technology fields)

• Balance of System components & application development

7

Installed capacity in 2015• World: 242 GWp (~90% is xSi)

• NL: 1.5 GWp (~1.3% of Dutch electricity use)

• TKI general target: 100 GWp in 2050

FhG ISE, PV report 20 October 2016

8

Considerations for the roadmapThis part of the roadmap focuses on xSi MODULES

• Types of modules that are considered:

• Low cost

• High power

• Ready for integration (BIPV, shade, …)

Goals are defined for

• Module costs : €• Extrapolate from historical data

• Module power : Wp

• cell efficiency - limits

• cell to module changes

• Module energy yield : kWh

• Irradiation (front/rear, direct/diffuse, …)

• Temperature dependence

• Module lifetime : years

• # years with >80% performance

Goal: reduce LCOE (€/kWh)

LCOE ~ 𝒄𝒐𝒔𝒕𝒔 (

€

𝑾𝒑)

𝒖𝒕𝒊𝒍𝒊𝒔𝒂𝒕𝒊𝒐𝒏𝒌𝑾𝒉

𝒌𝑾𝒑,𝒍𝒊𝒇𝒆𝒕𝒊𝒎𝒆(𝒚𝒓)

9

Price and Costs trends:

Expectations 2030:

• World: 250 GWp1 TWp

• Price 0.3 USD/Wp

What about costs?

• Healthy industry: margin!

Around 2030??

2004 2012

2016

Reduce costs in €/Wp

10

Efficiency limits of crystalline silicon

October 2016: 26.3%

achieved by Kaneka Corp using

IBC-HJ technology

Average in industry: 18 – 22%

Cell efficiency: 21% 29%

Module efficiency: ~1% lower

Typical cell efficiencies:

“black body” limit for c-Si: ~32%

“practical limit”: ~ 29%

Albert Polman, Mark Knight, Erik C. Garnett, Bruno Ehrler, Wim C. Sinke

Science 15 Apr 2016: Vol. 352, Issue 6283, DOI: 10.1126/science.aad4424

Increase energy in Wp

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Energy yield: irradiation

After Duffie & Beckman: Solar Engineering of Thermal Processes

• Also use rear side of the module

• Improve light capture from low angles

Increase energy yield in kWh/kWp

Will increase generated energy for

the same module

12

Summary:

Innovation goals for different solar PV product groupsLowest cost solar PV products 2016 2020 2030 2050

Power output/ surface (efficiency) Wp/m2 (%) 192 (19.2%) 206 (20.6%) 220 (22%) 242 (24.2%)

Power output / 60 cells module Wp 308 330 350 390

Costs/ unit surface area EUR/m2 100 82.4 <66 <50

Costs / max. power output EUR/Wp 0.52 <0.4 <0.3 <<0.2

Lifetime at >80% performance Years 25 30 35 35

Yield 1. improved T-coefficient

2. bifacial applicationkWh/ kWp

900

954

910

1200

920

1350

930

1430

Highest power output solar PV products 2016 2020 2030 2050

Power output/ surface (efficiency) Wp/m2 (%) 200 (20%) 238 (23,8%) 270 (27%) 280 (28%)

Power output / 60 cells module Wp 320 380 430 450

Costs/ unit surface area * EUR/m2 120 119 108 <112

Costs / max. power output EUR/Wp 0.6 – 0.8 0.5 – 0.6 0.4 <0.4

Lifetime at >80% performance Years 25 30 35 35

Yield improved T-coefficient by HJ kWh/ kWp 900 920 950 950

Best fit for integration solar PV products 2016 2020 2030 2050

Recycling – craddle – to - craddle Not yet LCA should be part of all cell/module research. Actual

implementation will depend a lot on government regulations

Form freedom – applicable on % of rooftops / facades 20% 30% 50% 60%

Shade tolerance – gain over standard PV modules 2% 10% 20% … %

Color flexibility – adaptable without efficiency losses Blue, black + green, yellow + red All colors

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Focus on:Lowest cost solar PV products 2016 2020 2030 2050

Costs / max. power output EUR/Wp 0.52 <0.4 <0.3 <<0.2

Lifetime at >80% performance Years 25 30 35 35

Yield 1. improved T-coefficient

2. bifacial applicationkWh/ kWp

900

954910

1200920

1350930

1430

Highest power output solar PV products 2016 2020 2030 2050

Power output/ surface

(efficiency) Wp/m2

%

200

20%

238

23,8%

270

27%

280

28%

Power output / 60 cells

moduleWp 320 380

430 450

Best fit for integration solar PV products 2016 2020 2030 2050

Form freedom – applicable on % of rooftops /

facades

20% 30% 50% 60%

Shade tolerance – gain over standard PV

modules

2% 10% 20% 50%

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Crystalline silicon cell and module

or

p-type

n-type

From goals to research topics: loss analysis

15

Losses in crystalline silicon cells

• Metallization grid: shading

• Other optical losses: absorption in cell layers, internal (back) reflection

• Recombination losses: at contacts, surfaces, p-n junction, in the emitter

and in the bulk

• Ohmic losses: lateral and contact resistances

29.3% maximal efficiency 21% n-Pasha cell

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Losses in modules

Optics: Absorption and

reflection in glass,

encapsulant

Resistive losses at the

interconnections

Optics: Absorption, reflection

in encapsulant and rear foil

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Research topics in 4 main R&D areas

1. Materials p- and n-type silicon, encapsulation materials, glass, ….

2. Junction formation and passivationhomo- and hetero- junctions, carrier selective, dielectric layers

3. Metallization and interconnectioncurrent collection on cell level, electrical interaction cell module

4. Light managementoptical properties on cell and module level, interaction cell module

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The research playing field

TRL 1:basic

principle

observed

TRL 2: technology

concept

TRL 3: experimental

Proof of

Concept

TRL 4: validation

in

laboratory

TRL 5: validation in

relevant

environment

TRL 6: demonstrate

technology

TRL 7: prototype at

pilot

scale

TRL 8: system

completed

and qualified

TRL 9: system

proven in

operation

Invention Concept validation Prototype bring concept towards industrialization

demonstration operation

Institutes:

Universities: laboratory

pilot

Industry: equipment factory

TRL = technology readiness level

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The Roadmap

• Goals in 4 main platforms

• Low cost xSi PV

• High power xSi PV

• Sustainable & reliable PV

• Integration of xSi PV

• Topics in 4 main R&D area’s

• Materials

• Junction / passivation

• Metallization

• Optics

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Under construction

< 0.3 €/Wp

27% module

> 35 years

Goals 2030:

1150 kWh/kWp

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R&D topics for lowest cost xSi PV products

Materials p-type silicon

Module materials

Materials in general

Junction /

passivation

n++ and p++ doping

Al2O3/SiNx stacks

Carrier select. Contacts

Light

management

Texture on multi

Bifacial operation

Annual Energy Yield

Metallisation

/interconnect

Printed metallization

Interconnection

Bifacial modules

Hydrogenation & gettering of impurities

glass-glass concepts, desert proof PV

High ohmic and selective diffusions

Black silicon / combined with selective emitter

Light trapping strips, light scattering busbars

Simulation and validation of AEY models

Stencil print, n,p-contacting pastes

Multiple busbars, low T soldering or glueing, shingled modules

White bifacial module

LPCVD polysilicon

1 2 3 4 5 6 7 8 9

Less material usage, recycling of materials, NO more silver sage

Bifacial modules, tracking of module s and / or systems

Copper metallization

Lowest cost solar PV products 2016 2020 2030 2050

Costs / max. power output EUR/Wp 0.52 <0.4 <0.3 <<0.2

Lifetime at >80% performance Years 25 30 35 35

Yield 1. improved T-coefficient

2. bifacial applicationkWh/ kWp

900

954

910

1200

920

1350

930

1430

PECVD / ALD deposition of (graded) dielectrics

21

Research on low cost modules

Ready for industrial implementation: TRL6-8

Bifacial n- or p-type, using polysilicon passivating contacts and printed

metallization

Implement cells into bifacial modules for 30% more kWh/kWp

TKI projects Nexpas and

Antilope

EU project Solar highways

22

R&D topics for highest power output xSi PV

products

Materials n-type silicon

Module materials

Junction /

passivation

p-n-junctions

Carrier select. Contacts

Beyond the limits of ‘simple’

silicon

Light

management

dv. optics cell level

Adv. optics module level

Beyond the limits of ‘simple’

silicon

Metallisation

/interconnect

Printed metallization

Alternative metallization

Foil interconnection

Hydrogenation, oxigen stacking faults, ingot yield

Encapsulant, foil interconnection

p/n junction formation and passivation

Nanostructures, nanowires, black silicon combined with selective emitter

Light trapping foils, light scattering structures

Low T / non firing through pastes

Cu/Ag plating, evaporated contacts

Bifacial IBC, glued shingled modules

1 2 3 4 5 6 7 8 9

Quantum dots, nanowire solar cells, bandgap manipulation, tandems…..

Up / down conversion, multiple exitons, tandems, ……..

Highest power output solar PV products 2016 2020 2030 2050

Power output/ surface

(efficiency) Wp/m2

%

200

20%

238

23,8%

270

27%

280

28%

Power output / 60 cells

moduleWp 320 380

430 450

High band gap passivating contacts,ALD Metal-oxides,

PECVD a-Si, Hetero Junctions

23

Research on high power modulesNovel topics, going from lab to institute: TRL3-5

Transparent carrier selective contacts and nanowire metallization

Back contact modules with IBC cellsUsing Metal oxides or poly-Si passivating contacts

TKI project Compass

TKI project IBChampion

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Generic R&D topics for sustainability & reliability2016 2020 2030 2050

Recycling – craddle – to - craddle- Not yet

LCA should be part of all cell/module research. Actual

implementation will depend a lot on government regulations

Lifetime at >80% performance Years 25 30 35 35

Yield 1)improved T-coefficient by

introducing Heterojunctions

2) bifacial application

kWh/ kWp900

954

920

1046

950

1150

950

1209

Materials Silicon

Module materials

characterization

Junction /

passivation

Stability of junction and (field)

passivation

characterization

Light

management

Soiling stability

Light trapping

characterization

Metallisation

/interconnect

Reliability

Stability

Characterization

Oxigen in Cz: PID, LeTID

(photo)chemical stability, delamination after stress

UV-ID and LID on module level

Anti-soiling (foil, structured glass), combination with LTF

Soldered and glued contacts w/o FF losses

IEC stability tests for all new materials

Leakage current behavior and control

Desert proof applications

PID on cell level, influence of charges

1 2 3 4 5 6 7 8 9

Fast (inline) characterization of bulk lifetime, defects and impurities

Separate surface, contact and bulk recombination

Fast (inline) optical measurements on cells and modules

Accurate inline measurements of resistive losses on cell and modules

25

Research on lifetime and reliability

Potential induced degradation

understanding of underlying

physics

Stability tests on rooftop

Fundamental study of failure

mechanisms

0%

2%

4%

6%

8%

10%

12%

0 20 40 60 80 100

Eta

lo

ss (

Jsc*

Vo

c l

oss

)

PID time (h) @ -1000V, 60°C, 85% RH

optimized B-emitter/optimized dielectric

non-optimized B-emitter/optimized dielectric

non-optimized B-emitter/improved dielectric

optimized B-emitter/non-optimized dielectric

non-optimized B-emitter/non-optimized dielectric

0%

1%

2%

3%

4%

5%

0 50 100 150 200 250 300 350

Eta

lo

ss (

Jsc*

Vo

c l

oss

)

UV time (h) @ 351 nm, 1.55W/m2/nm; total UV 62 W/m2BA

2007 – 2016

Various projects

26

R&D topics for integration of xSi productsBest fit for integration solar PV products 2016 2020 2030 2050

Form freedom – applicable on % of rooftops / facades 20% 30% 50% 60%

Shade tolerance – gain over standard PV modules 2% 10% 20% … %

Color flexibility – adaptable without efficiency losses Blue, black + green, yellow + red All colors

Materials Module materials

Light

management

Location / position

color

Metallisation

/interconnect

Different sized / freeform shade

tolerant modules

Low cost or high power (mini) modules serve as building blocks

Parallel / series mini-module in module

Smart modules, power optimizers

1 2 3 4 5 6 7 8 9

Tracking of modules / racks of modules

Large scale modules

Other topics for applications will be added in a next update of the

crystalline silicon roadmap

Colored modules, thermal management by IR

interference filters

Remote system modelling on energy yield

Smart cell power management in modules

27

Research on implementationsShade tolerant / smart modules

TESSERA module

Building applied or integrated

Low-current

diode

Exasun

Tesla

Various TKI projects

28

TKI Urban Energy roadmap

• Steer and focus research

• Measure progress

• Benchmark internationally

Research platforms and areas

defined

xSi goals for 2030:

• Cost < 0.3 €/Wp

• Module efficiency 27%

• Lifetime > 35 years

• Energy yield 1150 kWh/kWp

Summary

< 0.3 €/Wp

27% module

> 35 years

Goals 2030:

1150 kWh/kWp

29

Thank you for your attention!

For questions:romijn@ecn.nl

wijnand@tki-urbanenergy.nl

Sunfloat, ECN and Tempress technology