eco-solar factory - 40%plus eco-efficiency gains in the...

Workshop: How to create value from PV waste? 10.04. 2018 Munich Germany.

Eco-Solar Factory - 40%plus eco-efficiency gains in the photovoltaic value chain with minimised resource and energy consumption by closed loop systems

Outline

• Background

• Eco-Solar roadmap

• Recent results and highlights

• Environmental impact

2

3

Consortium

Partner Country Category

SINTEF NO Research

Norsun NO Industry

SoliTek LT SME

ISC Konstanz DE Research

Apollon Solar FR Industry

Garbo IT SME

BCC NL SME

bifa DE SME

Aimen ES Research

Steuler NO SME

Ingesea ES SME

Start date: 1. October 2015 Duration: 36 months Total budget = 5,642,707.50 € Total EU funding = 5,642,707.50 € Type of action: Research and Innovation Actions (RIA)

Work programme topics addressed: FoF-13-2015: Re-use and remanufacturing technologies and equipment for sustainable product lifecycle management

Importance of Eco-manufacturing

4

Market outlook for the next decades: cumulative installed capacity worldwide based on different scenarios

Importance of Eco-manufacturing

5

*Assumptions: high-ren scenario (1800 GW in 2030), market 100% c-Si, business as usual

Expected resource consumption and savings by 2030 (in Mega tonnes). (Note: worldwide silver resources in 2014 belong to 0.52 Mt.)

*The evolution of PV waste in Europe, May 2013, Sandt Consulting and European Centre for the Recycling of Solar Energy (CERES). Photo: [PVCYCLE]

End-of-life PV module waste

• Maximising resource and process efficiency

• Introducing design for repair, reuse and

recycling

6

General approach – Circular Economy

Eco-Solar roadmap

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Argon purge gas recycling

• 4 million nm3 of argon are used per 1GWp of

silicon wafer output

• The exhaust argon is vented to atmosphere after

passing through the crystal growing process

• Argon costs vary geographically but are in the

range of $0.5 to $1.5 per nm3

• Can account for up to 10% of the wafer cost

8

Recovery & reuse during Si-ingot crystallisation

• System uses a unique solid state Chemical Looping

Combustion reactor

• Reactor combusts CO, H2, CH4 and trace vacuum pump

oil to CO2 and H2O

• Combustion products adsorbed onto molecular sieve

• ≥95% purge gas recovery rate

• Typical gas purity of ~99.9998% pure excluding N2

Recovery & reuse during Si-ingot crystallisation Argon purge gas recycling

• Cells fabricated from ingots produced using recycled argon are indistinguishable from cells fabricated

from normal ingots(ref: Konstanz test)

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• 2 N-type bifacial modules with cells from ISC-Konstanz (n-type Norsun Si material with Ar recycling)

• Fully functional modules with comparable performance as standard modules

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Module ID

Isc [A]

Imp [A]

Voc [V]

Vmp [V]

Pmp [W]

Norsun Ar recycling #1

Sunny side 9.74 9.40 39.33 29.06 273.00

Back side 7.96 7.66 38.58 30.15 230.95

Norsun Ar recycling #2

Sunny side 9.72 9.40 39.31 29.27 275.15

Back side 8.00 7.69 38.60 30.11 231.66



• The gas purity analysis, excluding N2, is better than 99,99999%.

• There are no detectable adverse effects from using the Argon recycling system.

• Recycling rate > 95%

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From July 2016 to August 2017

Year 2016 2017

Ref. (kg) 1 520 810 1 257 351

Recycled Ar (kg) 166 855 156 430

Saved Argon 11% 12%



Reusable crucibles based on advanced Si3N4 ceramics

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• Silica crucibles can be only used once (cracks after usage (a))

• Up to ~30% of the conversion cost from poly-Si to the as-grown ingot

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After crystallisation Ingot release from crucible 1st mc-Si ingot (~15kg)

Si3N4 crucible was used in 5 subsequent runs



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• The best solar cells (17.7% – 17.9%) were sorted and carefully selected for a glass/glass module production giving a module output comparable to industrial type solar modules.

Module Isc (A)

Imp (A) Voc (V)

Vmp (V)

Pmp (W)

A: Si3N4 8.95 8.45 38.53 30.90 260.93

B: commercial (17.5%-17.7%) 9.14 8.54 38.21 30.16 257.63



Anode material in Lithium Ion batteries 17

Recovery & reuse of Si-kerf-loss

• Only the coolant is recycled by

today

• Separated Si-kerf-loss is landfilled

or used as low grade alloying

compound in foundry applications

• No value at the moment is

extracted from this material

• Objective: reduction of Si-waste

by 80% due to reutilization as Si-

feedstock or other high end

markets

Si-powder

Si-granules Si-pellets

mc-Si ingot

Secondary raw material in Si3N4 crucibles

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• Silicon as anodes in Li ion batteries

• Silicon has 10x higher capacity than graphite

• Voltage * capacity = Energy

• Not stable during (de)lithiation due to volume changes

• Material cost very important

Lithium Ion Batteries


• Used Garbo cleaned Si kerf.

• Irregular shaped particles

• Monodisperse particle size distribution

(probably agglomerates)

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0.1 1 10 1000

2

4

6

8

10

12

14

Pa

rtic

le s

ize

dis

trib

utio

n (

%)

Particle size (µm)

D10

: 0.584 µm

D50

: 0.995 µm

D90

: 2.071 µm

Si-kerf

0

20

40

60

80

100

Cu

mu

lativ

e c

urv

eRecovery & reuse of Si-kerf-loss

Lithium Ion Batteries

• Used Garbo cleaned Si kerf.

• Added Super C 65 carbon black as conducting agent

and Na CMC (carboxymethylcellulose) as binder

• Coin cells with Li as counter electrode

with different loading

• FEC (fluoroethylene carbonate ) as

electrolyte additive to stabilize the SEI

(Solid electrolyte interface )

• Up to 300 cycles at a limited capacity of

1000 mAh/g reached

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50 100 150 200 250 300 3500

200

400

600

800

1000

1200

1400

Sp

ecific

ca

pa

city (

mA

hg

-1)

Cycle number

80 wt. % kerf 1 mg (Si) /cm2

70 wt. % kerf 1 mg (Si) /cm2

70 wt. % kerf 0.7 mg (Si) /cm2

C/5Lithiation capacity limited to 1000 mAhg-1

50 100 150 200 250 300 350

0.1

0.2

0.3

0.4

0.5

end potential

end potential

end potential

Lithia

tion e

nd p

ote

ntial vs. Li/Li+

(V

)

Cycle number

95

96

97

98

99

100

101 CE

CE

CE

Coulo

mbic

effic

iency (%

)

0 20 40 60 800

500

1000

1500

2000

2500

3000 70 wt. % kerf 1 mg (Si) /cm

2

70 wt. % kerf 0.7 mg (Si) /cm2

Q d

isch

arg

e (

mA

hg

-1)

Cycle number

Cycling between 0.05-1V at C/5

0 500 1000 1500 2000 25000.0

0.2

0.4

0.6

0.8

1.0

Po

ten

tia

l vs L

i/L

i+ (

V)

Specific capacity (mAhg-1)

Cycle 10

Recovery & reuse of Si-kerf-loss Lithium Ion Batteries

Si3N4 crucibles

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10% Si-kerf-loss

20% Si-kerf-loss

G1 crucible made from x% Si-kerf-loss before (right image) and after (right image) nitridation.


Silver

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Remanufacturing & resource efficiency in cell processing

Wet chemical processes

• Solar cell architectures

• Interconnection schemes

• Metallization pastes that contain less silver

• Objective: 66% savings of silver

• de-ionised water is used in several

cleaning steps

• Reducing wet chemical consumption

and process steps

Current solar cell design

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Remanufacturing & resource efficiency in cell processing Repair and recycling of solar cells

• Shunts, certain types of cracks

• Recovering badly damaged cells by

laser cutting-out critical damages

• Repair of recycled solar cells

Cell-doctor

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Eco-Solar printing layout tested on mc and BiSoN cells

Silver


Best known

method

Eco-Solar

approach

Relative savings

/ change in

performance

Finger screen opening width 35 µm 20 µm

Finger width 47 µm 45 µm

Fingers (1st print) 83 mg 57 mg

Fingers (2nd print) - 21 mg

Busbars 34 mg -

Rear side pads (assumed) 35 mg -

Total paste 152 mg 78 mg - 49 %

Total silver (contact paste 85% silver,

pad paste 50%) [per 60 cell module]

117 mg

[7 g]

66 mg

[3,9 g]

- 36 %

Eta (measured with extra BB) 17,6 % 17,5 % - 0,6%

FF (measured with extra BB) 79,0 % 78,8 % - 0,2%

Voc (measured with extra BB) 626 mV 626 mV 0 %

Jsc (measured with extra BB) 35,6 mA/cm² 35,6 mA/cm² 0 %

Leave out busbars.


Wet chemical processing steps required to process mc-solar cells

por-Si removal por-Si removal PSG

HF HNO3 KOH HCl HF HF HNO3 KOH HCl HF HF

7,00% 26,0% 3,00% 9,40% 4,70% 2,00% 42,00% 3,00% 9,40% 4,70% 5,00%

KOH H2O2 Additive HF O3 HCl HF

2,0% 2,0% 0,1% 0,1% 20 - 25 ppm 2,0% 1,8%

KOH Additive O3 HCl dHF

2,0% 0,1% 20 - 25 ppm 2,0% 0,2%0,1%

Ecosolar 1

cleaningindustrial process

cleaning edge isolation

pre-clean cleaning 1 cleaning 2

CH3COOH

8,6%

texturing

texturing

Ecosolar 2texturing cleaning 2

KOH

2,0%

cleaning 1

HCl

• Wet chemical edge isolation replaced by novel laser process that lasers on the actual edge of the wafer.

• Alkaline processing (texturing) of diamond sawn mc-wafers.

• Development of a diffusion process that does not require PSG removal

• Reduction of HF content in cleaning baths to the minimum.

• Recovery of rinsing water to a large extend.

Wet chemicals


Cell doctor:

• First approach on defect

identification issues in mc solar

cells multicrystalline

• A first methodology (based on k-

means binary tree) is actually

under test.

• A first selection for industrial PC

for integration has been done.

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Module design for remanufacturing (NICE) Disassembly "end-of-life" modules for recovery of module components

Organics

• EVA for encapsulation

• PVF in backsheets

• 90% less organics

• frameless module

• 60% less aluminium

Aluminium

Module design for remanufacturing (NICE)

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Copper Tabs

• Recovery of front glass as entire piece for re-use

• Recovery of copper wires

for re-use

Disassembly "end-of-life" modules for recovery of module components

Module design for remanufacturing (NICE)

Module ID Isc [A] Imp [A]

Voc [V]

Vmp [W]

Pmp [W]

Eco-Solar old glass #1

8.87 8.29 38.26 30.27 250.88

Eco-Solar old glass #2

8.92 8.33 38.35 30.30 252.53

(No ARC on front glass)

• Reuse of recovered front glass

• 60 cells laminated glass/backsheet module by Solitek

• Standard lamination process

• Fully functional new module

Disassembly "end-of-life" modules for recovery of module components

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2.55 0.43 6.47 279 1,73 1.86 1.99

0.460.06

2.90

14

1,00

0.20

0.88

0.230.6

2.55

62

0.08

0.8

1.83

Argon[kg]

Ceramics[kg]

Silver[g]

DI-water[kg]

Aluminium[kg]

Organics[kg]

Silicon[kg]

Baseline Project proposal target value Midterm LCA "all project developments"

Figure 1: All project developments: reduction of waste and resource consumption per production of 1 mono-Si based PV-module (60 6-inch solar cells) envisaged at the beginning of the project and the current degrees of achievement after implementing of all project developments from the project partners

Preliminary LCI baseline of the module production

Environmental impact

eco-solar factory - 40%plus eco-efficiency gains in the...

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