EcoSolar Factory – 40% plus eco-efficiency gains in the photovoltaic value chain

with minimised resource and energy consumption by closed loop systems

ECOSOLAR FACTORY

Silver

Argon purge gas

crucibles

Si ingot

DI water

process chemicals

process organics

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low process efficiency

difficult disassembly

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

re-use Argon purge gas

use Si-kerfloss in Li-ion batteries

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

IMPACT

innovative module design

module assembly

re-use DI water

easy disassembly

sealing modules

process efficiency

no material degradation

energy efficiency

repair

diagnostics

European Union reduced resource component This project received support from consumption re-distribution the European Union in the Horizon 2020 programme

reduced energy consumption

Aluminium

installation

copper recycling

end of life

re-use of glass

ECOSOLAR Eco-Solar Factory – 40% plus eco-efficiency gains in the photovoltaic value chain with minimised resource and energy consumption by closed loop systems Duration: 2015-2018 H2020 project Grant agreement no: 679692 H2020-FoF-2015 FoF-13-2015 Re-use and remanufacturing technologies and equipment for sustainable product lifecycle management Document date: January 2023

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

CONTENTS ABSTRACT

1

9

MULTIPLE PROBLEMS, INTEGRATED SOLUTIONS

10-11

BACKGROUND

14-15

THE “PHOTOVOLTAIC WASTE” ISSUE

ECOSOLAR

16-19

THE HOLISTIC APPROACH

FIVE DOMAINS

20-21

INPUTS, PROBLEMS, PRODUCTION, STRATEGIES, IMPACT

FOCUS

22-23

INTERVENING IN THE PRODUCTION PROCESS

ACHIEVEMENTS

24-25

PROJECTED AND REDUCED RESOURCE CONSUMPTION

ACHIEVEMENTS CARBON FOOTRPINT AND GLOBAL WARMING

26-27

2

CHAINS OF EFFECTS: APPROACHES IN DETAIL

28-29

I

CRYSTALLIZATION

30-37

RECOVERING ARGON, RE-USING CRUCIBLES

II

WAFERING

38-41

UTILIZING KERF LOSS

III

CELL PROCESSING

42-47

REDUCING SILVER CONSUMPTION, RE-USING DI WATER, EFFICIENT CHEMICAL PROCESSING

IV

MODULE ASSEMBLY

48-51

INNOVATIVE MODULE DESIGN FOR DISASSEMBLY AND RECYLING

V

CELL REPARATION

52-55

ECOLOGICAL AND ECONOMIC ASSET

VI

LIFE CYCLE ASSESSMENT

56-59

PROCESS ANALYSIS AND ENVIRONMENTAL IMPACT

IMPRINT PROJECT PARTNERS

62-63

8

9

ABSTRACT

EcoSolar envisions an integrated value chain to manufacture and implement solar panels in the most ecologic way by maximising resource efficiency, taking into account reuse of materials during production and repurposing solar panel components at end of life stage. EcoSolar demonstrated that during the lifetime of a solar electricity producing field, individual panels can be monitored, allowing to identify defaulting panels at an early stage, replacing or repairing them and thus to increase the overall energy yield.

In WP1, SINTEF and Norsun worked on recovery & reuse during silicon ingot crystallisation, addressing recovery of argon purge gas and work with Steuler on reusable crucibles. In WP2 Garbo recovered Si-kerf-loss during wafering, and worked with SINTEF on potential reuse applications, like Si-feedstock in crystallization processes, or as resource in crucible manufacturing or lithium ion battery production. In WP3, ISC and SoliTek looked into potential for re-using process water; reducing material resources, like chemicals and silver, by smarter solar cell design, more efficient processes and recovery and reuse of chemicals; AIMEN developed solar cell monitoring and repair for inline processing, to enable remanufacturing.

In WP4, Apollon used a module design that results in reduced bill of materials, enables remanufacturing and reuse of components from modules that showed failures after assembly or have been identified as malfunctioning in operating PV installations, based on integrated diagnosis techniques for the detection of failure modes. will collected data from all previous WPs to assess environmental impact of the intended innovations (WP5). bifa identified waste streams that are costly and hard to recycle and find opportunities to repurpose those waste products. BCC disseminated results and supported the partners with the exploitation and replication potential of the results (WP6).

10

11

ABSTRACT (continued)

At the end of the Eco-Solar project, the consortium wishes to demonstrate economic viable PV-modules that have been designed and manufactured for re-manufacturing.

Following the different lines of research we will demonstrate Eco-Solar PV-modules that have been produced with optimised recovery, reuse and resource efficient production methods. These demonstrator modules will: > be industrial size (60 cells) PV-modules > show less than 2% degradation of module performance after IEC 61215 degradation tests > have a mono-facial STC power of 260 Wp for multi-crystalline silicon (mc-Si) cells and 285 Wp for mono (solo)-crystalline silicon (sc-Si) cells > show that individual panels within a solar electricity producing field, can be monitored, so that defaulting panels can easily be spotted and repaired or replaced > be cost-competitive aiming for 5-8 ct/kWh

1 MULTIPLE PROBLEMS, INTEGRATED SOLUTIONS

30

29

28

27

20

20

20

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

0.25

20

20

20

20

20

20

20

10

11

20

20

20

20

20

20

20

20

20

20

20

14

3.00

2.75

2.50

2.25

2.00

1.75

1.50

1.25

1.00

0.75

0.50

EC OS OL AR

15

BACKGROUND THE “PHOTOVOLTAIC WASTE” ISSUE As a result of global efforts to reduce CO2 emissions and dependence on fossil fuels, the photovoltaic industry is focused on creating products that generate solar electricity.

As such, it is one of the fastest growing economic sectors, following an exponential growth curve since 1992 until now. Projections for photovoltaic growth are difficult and burdened with many uncertainties, and official agencies, such as the International Energy Agency, consistently increased their estimates over the years, still falling short of actual deployment.

The drawback of this fast deployment of photovoltaic products (like solar modules) is, that even though solar power is pollution-free during use, production of PV-modules consumes considerable energy and natural resources. The fast growth of the PVindustry entails similar fast growth in resource consumption with growing production capacity: currently modest amounts of use can become very high.

Moreover, recycling is hardly considered during module production, and therefore still cumbersome and inefficient. Therefore, it is necessary to design modules for end-of-life recycling to allow recovery and recycling of glass, wafers/cells in whole pieces, which will result in a much more (energy-) efficient method for harvesting and especially reusing the secondary raw material, in addition to sustainable improvements in each process step.

16

Silver

Si feedstock

Argon purge gas

crucibles

Si ingot

DI water

process chemicals

process organics

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low process efficiency

difficult disassembly

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

Aluminium

PROCESS INPUTS

PROBLEMS

innovative module design

module assembly

re-use DI water

easy disassembly

sealing modules

use Si-kerfloss in Li-ion batteries

process efficiency

no material degradation

energy efficiency

testing

repair

diagnostics

installation

end of life

enhanced disassembly

PRODUCTION CHAIN recycling

ECOSOLAR STRATEGIES re-use Argon purge gas

IMPACT

reduced resource consumption

component re-distribution

reduced energy consumption

copper recycling

re-use of glass

external use

17

ECOSOLAR THE HOLISTIC APPROACH The EcoSolar project aims to maximise resource productivity and reduce pollution in PV, through minimising use of critical resources like energy, water, chemicals, aluminium, silver and lead, while simultaneously maximising recycling possibilities, by introducing design for recovery, reuse and recycling in this sector. To realise this, collaborating over the value chain is imperative.

EcoSolar’s concept for improvements in waste reduction is to increase remanufacturing potential, including repair of PV-modules, while simultaneously improving reuse of resources and components and increasing resource efficiency, over the whole value chain. EcoSolar focused on multiple processing steps, where ecologic impact and economic gain are expected to be realised through the intended innovations. As shown in the figure, the project includes the monitoring of PV-modules after installation and their reuse and recycling potential within the PV-value chain and beyond.

A pan-industrial approach has been chosen to identify by-products, recycled and recovered wastes. With this information, the best possible ecological and efficient utilisation of raw materials and solutions for poorly recovered and reused materials can be presented. The results for the individual process steps, and their impact over the integrated value chain have been assessed with a LCA and eco-efficiency analysis methods to provide proof of their success in reducing the environmental footprint.

18

P RO J E CT O V E RV I E W Si feedstock

Silver

Argon purge gas

crucibles

Si ingot

DI water

process chemica

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low proc efficienc

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

re-use DI water

easy dis

use Si-kerfloss in Li-ion batteries

process efficiency

no mate degrada

testing

repair

diagnos

PROCESS INPUTS

PROBLEMS

innovat module

PRODUCTION CHAIN

ECOSOLAR STRATEGIES re-use Argon purge gas

s als

19

process organics

cess cy

difficult disassembly

tive e design

module assembly

sassembly

sealing modules

erial ation

energy efficiency

stics

Aluminium

installation

end of life

recycling

copper recycling

re-use of glass

reduced resource consumption

enhanced disassembly

external use

component re-distribution

reduced energy consumption

20

Silver

Si feedstock

Argon purge gas

crucibles

Si ingot

DI water

process chemicals

process organics

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low process efficiency

difficult disassembly

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

Aluminium

PROCESS INPUTS

PROBLEMS

innovative module design

module assembly

re-use DI water

easy disassembly

sealing modules

use Si-kerfloss in Li-ion batteries

process efficiency

no material degradation

energy efficiency

testing

repair

diagnostics

installation

end of life

enhanced disassembly

PRODUCTION CHAIN recycling

ECOSOLAR STRATEGIES re-use Argon purge gas

IMPACT

reduced resource consumption

component re-distribution

reduced energy consumption

copper recycling

re-use of glass

external use

21

FIVE DOMAINS INPUTS, PROBLEMS, PRODUCTION, STRATEGIES, IMPACT Improvements in waste reduction have been assessed over the whole value chain, by looking at the major process inputs: in terms of (near) scarcity, in terms of easy recyclability and in terms of large volumes of waste.

Based on this assessment, the major problems have been identified: the reasons why industry has not adapted remanufacturing, re-use or recycling options in their production process, which have led to strategies to solve these problems. By adapting the production processes, the impact will be created: > Reduced resource consumption > Component redistribution > Reduced energy consumptoin

22

I

II

III

crystallization

wafering

cell processing

VI

life cycle assessment

IV

module disassembly

V

recycling/ re-use

23

FOCUS INTERVENING IN THE PRODUCTION PROCESS The most important bottleneck for eco-friendly solar panels is the PV-module design.

Current modules encapsulate the solar cells using EVA (Ethyl Vinyl Acetate) which, due to the high temperatures involved, acquires a dense cross-linked structure, and becomes hard and chemically resistant, complicating recycling of PV modules. Modules must be destroyed and treated under extreme conditions such as extended treatment at high temperatures to recover the component pieces as impure fragments. Without a design where the module can be reopened after assembly, repair, recovery of components and hence remanufacturing will be impossible. Therefore, the project will use Apollon Solar’s design of PV-modules that can easily be disassembled and separated into their different components. From this starting point, the whole value chain, from silicon feedstock to modules has been assessed for improvements without losing competitive edge.

The process from Si feedstock to wafering should ideally recover and reuse an maximum amount of consumables, such as crucibles and argon. Moreover, it should recover a maximum amount of resource materials (like Si-kerf) to be reused within the feedstock process or within another market, leading to the consumption of minal energy, but resulting in a high yield.

Solar cell processing should ideally use a minimum of (near) critical materials such as silver. Moreover, it should Avoid using of chemicals in cell processing steps, such as during texturisation and cleaning, emitter formation and etch isolation. In addition, it should recover and reuse a maximum amount of water and chemicals within the production process. It should also enable an option for automated repair of defective silicon cells and wafers, within the manufacturing line, combined with a high yield and throughput.

Solar modules should ideally be easy to open after sealing, so that they can be repaired if rejected at failure control or when sent back from PV-fields. Moreover, this would also allow salvaging of glass, solar cells and copper tabs, and allow for avoid using aluminium frames.

24

18

Ar

Ceramics (kg)

Argon gas (kg)

3,0

0,5

2,5

0,4

2,0

0,3

1,5

0,2

1,0

0,1

0,5 0,0

0,0

47

Ag

2.55

0.46

0.23

baseline

p ro j e c t t a rg e t value

p ro j e c t re s u l t value

0.06

0.06

DI water (kg)

Silver (g)

300

8 7 6 5 4 3 2 1 0

250 200 150 100 50 0 6.47

13

Al

2.90

3.34

279

14

7.08a

Organics (kg)

Aluminium (kg)

2,5

2,0

2,0

1,5

1,5

1,0

1,0

0,5

0,5

0,0

0,0 1.73

1.00

0.08

Silicon (kg)

2,0 1,5 1,0 0,5 0,0

0.43

1.99

0.88

1.6

2.44

0.20

0.32

25

ACHIEVEMENTS PROJECTED AND REDUCED RESOURCE CONSUMPTION Through the different solutions and strategies EcoSolar reduced the waste generation within the PV-industry, but also beyond. Our overall impact on non-renewable materials is shown in the figures, where we have visualised the impact of our resource efficiency, reuse and reducing amounts of waste within the PV-value chain.

The seven resources depicted on the left could be used more effectively during the production process, resulting in significant reductions in consumption and costs. Each graph depicts the baseline measurement or estimation, the project target value and the results that have been obtained.

These numbers apply to mono-Si and multi-Si modules. The values given here are based on a mono-Si PV module of 1.62 m2.

26

mono-Si

350

baseline

300

midterm LCA re s u l t

250 200 150 100 50 0

277

316

174

208

total

31

33

ingot

19

21

wafer

cell

55

52

module

multi-Si

200

baseline midterm LCA re s u l t

150

100

50

0

164

192 total

63

85 ingot

28

30 wafer

21

22 cell

55

52

module

27

ACHIEVEMENTS CARBON FOOTPRINT AND GLOBAL WARMING The combination of different strategies that has been implemented in the production process results in significant reductions in the carbon footprint of the PV-module production process. In turn, this reduction contributes to the reduction of global warming. In each of the production steps, measurements have been made and models have been used to calculate or approximate the respective carbon footprint reduction.

2 CHAINS OF EFFECTS: APPROACHES IN DETAIL

30

Silver

Si feedstock

Argon purge gas

crucibles

Si ingot

DI water

process chemicals

process organics

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low process efficiency

difficult disassembly

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

Aluminium

PROCESS INPUTS

PROBLEMS

innovative module design

module assembly

re-use DI water

easy disassembly

sealing modules

use Si-kerfloss in Li-ion batteries

process efficiency

no material degradation

energy efficiency

testing

repair

diagnostics

installation

end of life

enhanced disassembly

PRODUCTION CHAIN recycling

ECOSOLAR STRATEGIES re-use Argon purge gas

IMPACT

reduced resource consumption

component re-distribution

reduced energy consumption

copper recycling

re-use of glass

external use

31

I

CRYSTALLIZATION RECOVERING ARGON RE-USING CRUCIBLES During crystallization, pure argon gas, used to remove contaminants, is currently being vented into the air. The effluent argon gas is typically composed of argon and a few contaminants at the particles per million (ppm) level, chiefly composed of carbon monoxide, hydrogen, methane and other hydrocarbons.

Though perhaps argon is abundantly available in the earth’s atmosphere (approximately 1% of mass), there are still (ecological and financial) costs involved in the production of pure gas. For instance, NorSun’s wafer facility with an equivalent output of ~350 MWp of wafers per year, requires ~1.4 million Nm3 argon, resulting in a typical bill of 0.7–1.4 million EUR per year, accounting for 3–5% of the wafer cost.

Though in other industries, argon gas recycling has become state of the art, in PVproduction this was not yet the case. However, Gas Recovery and Recycle Ltd. (GR2L) has developed a relatively simple and cost efficient technique for argon-gas-recycling, providing a recovered gas stream of around 99.9999% purity. This method is based on a chemical looping combustion process to convert combustible species in the exhaust gas stream to carbon dioxide and water, followed by efficient of carbon dioxide and water in re-generable reactor beds. Such a recycling system has been integrated in NorSun’s factory collecting and recycling exhaust gas from 8 crystal pullers. First results from crystals grown with argon recycling show similar material performance as grown by standard process without recycling. In the near future, solar cells and modules will be manufactured from this material to confirm the technological potential and qualify for customers.

Savings of over 95% could be realised if the wasted argon is purified and re-used, as has been assessed by bifa in an LCA.

single Si crystal ingot (so-called monocrystalline silicon) for optimum conductivity

32

Argon atmosphere The Argon is recirculated and re-used

1 ingot is

1 crystal

made under

seed crystal is slowly pulled through liquid Si

a

special atmosphere

ongoing crystallization (from liquid Si to solid single Si crystal)

CRYSTALLIZATION (MONOCRYSTALLINE)

ingot is wafered into single cells

process step: crystallization

resource: Argon purge gas

impact: reduce resource use

ingots are made under inert atmosphere

Argon gas will be catched

this gas can be re-used in a second round

34

CRYSTALLIZATION (continued)

During the crystallisation step, crucibles are the main containers for the (molten) silicon feedstock. As silicon at high temperature reacts easily with almost everything, there are only a few crucible materials that will meet purity requirements for manufactures. One of the main drawbacks of using silica, as is current standard practice, is the (ecologic and financial) cost due to single use. Silica crucibles contribute up to ~30% of the conversion cost from Si-feedstock to the as-grown ingot.

STEULER has developed a concept for reusable silicon nitride crucibles, for both crystallization processes, DS and Cz. In Eco-Solar the technical potential of these crucibles for crystallisation of multicrystalline silicon has been investigated at SINTEF. Currently, one silicon nitride crucible has been used for 5 subsequent crystallisation runs. The obtained silicon material quality is similar to material crystallized from Electronic Grade HighPurity Quartz crucibles. It is aimed for at least 10 times reuse. The near future plan is to scale it up to larger silicon ingots and then to manufacture solar cells and modules out of the silicon grown in this material in order to demonstrate that this technique is suitable for PV applications.

Savings of more than 85% can be realized with this novel technology.

35

1 ingot costs

1 crucible

6 ingots cost

1 crucible

36

1 ingot costs

1 crucible Si ingot production is expensive, as each crucible breaks

crucibles are as of yet not recycled

crucibles break through attachment of the Silicon to the crucible material

attachment leads to material degradation, cracks and breaking

CRYSTALLIZATION (MULTICRYSTALLINE)

process step: crystallization

resource: crucibles

impact: reduce resource use

ingots break during crystallization

new ingots can be used more than once

resources and costs are reduced

38

Silver

Si feedstock

Argon purge gas

crucibles

Si ingot

DI water

process chemicals

process organics

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low process efficiency

difficult disassembly

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

Aluminium

PROCESS INPUTS

PROBLEMS

innovative module design

module assembly

re-use DI water

easy disassembly

sealing modules

use Si-kerfloss in Li-ion batteries

process efficiency

no material degradation

energy efficiency

testing

repair

diagnostics

installation

end of life

enhanced disassembly

PRODUCTION CHAIN recycling

ECOSOLAR STRATEGIES re-use Argon purge gas

IMPACT

reduced resource consumption

component re-distribution

reduced energy consumption

copper recycling

re-use of glass

external use

39

II

WAFERING UTILIZING KERF LOSS After crystallization, side-, top- and bottom-parts are removed before the ingot is cut into blocks and then wafered. A considerable amount of silicon is lost in form submicron powders (kerf-loss) during the cutting processing of silicon ingots to obtain wafers: up to 50% of starting silicon goes into the coolant used during the sawing of silicon wafers.

The ability to recycle the kerf-loss for solar ingot production will have beneficial effect in terms of savings of precious poly-silicon consumption and of waste reduction.

Therefore, Garbo has patented and implemented a silicon recycling process which removes contaminations and brings silicon to ‘five nines’ (or 5N), i.e. 99,999% purity.

Purified silicon is then dried, compacted and packed under vacuum in order to obtain a stable silicon powder, that however needs to undergo a high temperature oxygen degassing process before being used as feed material in the standard production of solar ingots and cells.

Within Eco-Solar, the consortium investigated 3 factors that will give both environmental and monetary gain. Garbo will look at reducing chemicals consumption in Si kerf cleaning step and improving compact density of powders, while NorSun carried out sawing tests with increased kerf-loss saturation level in sawing coolant, for Garbo to study if the saturation level in the coolant affects the coolant recycling process and the recycled coolant quality, even if no variations are expected in this respect.

In total, the impact from the innovations could be saving more than 70% of the silicon kerf-loss, which has been assessed by bifa.

40

towards crystallization part of the kerf loss is re-used in the feedstock for the production of new ingots

part of the kerf loss is re-used in the Lithium (Li) batteries

wafers are used in cell processing

the overall impact of this strategy is to reduce resource consumption, notably Silicium (Si)

WAFERING diamond sawing wire

ingot process step: wafering

resource: kerf loss

impact: reduce resource use

solar cells are made by wafering ingots

while cutting, the dust is extracted for recycling

dust is utilized in batteries or feedstock

42

Silver

Si feedstock

Argon purge gas

crucibles

Si ingot

DI water

process chemicals

process organics

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low process efficiency

difficult disassembly

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

Aluminium

PROCESS INPUTS

PROBLEMS

innovative module design

module assembly

re-use DI water

easy disassembly

sealing modules

use Si-kerfloss in Li-ion batteries

process efficiency

no material degradation

energy efficiency

testing

repair

diagnostics

installation

end of life

enhanced disassembly

PRODUCTION CHAIN recycling

ECOSOLAR STRATEGIES re-use Argon purge gas

IMPACT

reduced resource consumption

component re-distribution

reduced energy consumption

copper recycling

re-use of glass

external use

43

III

CELL PROCESSING REDUCING SILVER CONSUMPTION RE-USING DI WATER EFFICIENT CHEMICAL PROCESSING In crystalline solar cell manufacturing, when wafers are being processed into solar cells, several wet chemical etching and cleaning steps are implemented, which have negative impact on the environmental footprint. By reducing and avoiding certain chemicals or metals (e.g. HF, Pb, Ag, Al) and using less pure or recycled chemicals, waste can be reduced and the ecologic footprint of solar cells and panels can be improved.

Especially silver is an important element, as it is used in most solar cells (over 98%) currently produced, providing the metal contact that ‘collects’ and ‘drains’ the current from the solar cell, resulting in todays silver consumption for PV of about 15% of the total silver market with the expectation to rapidly grow further.

In the Eco-Solar project, ISC-Konstanz experimented with different solar cell architectures, to minimize the use of Ag. In addition, an innovative interconnection scheme enabled

by Apollon’s module design, allows us to avoid soldering of a contact tape onto the rear side Ag pads and the front side busbars. Only the small contact fingers on the front side are needed.

In addition, ISC-Konstanz and SoliTek tested an alkaline saw damage removal and texturization to replace the current state of the art concentrated HF:HNO3 mixture, HF reduction in cleaning process is also investigated. Advanced processes for emitter formation are developed that will enable higher throughput, resource efficiency and avoid the needs for chemical phosphorous glass layer removal (PSG-removal).

AIMEN further developed advanced laser treatment, in order to minimize the cut-off area at the wafer edges to a negligible fraction of the whole wafer area, to avoid the wet chemistry normally used to separate the front and rear of the solar cells.

44

CELL PROCESSING (continued)

During the processing of wafers in to solar cells, water is mainly used for cleaning: after each chemical processing step, the wafers are rinsed with de-ionized, ultra-clean, water.

Afterwards, the water that goes down the drain, is often of higher quality than the water contracted from the tap.

One of the cornerstones of environmental protection in Europe, is the protection of water resources, of fresh and salt-water ecosystems and of the water we drink and bathe in.

With the example of Solitek, where solar cell processing with a production capacity of 80MW, consumes about 54.000m3 of de-ionized water per year, it becomes clear that recycling systems for waste water can have a large impact.

Therefore, ISC-Konstanz looked into industrial viability of recycling systems for waste water, and investigate its potential for saving more than 90% in solar cell processing, while bifa will assess the environmental benefits via an LCA.

45

46

DI water used for rinsing is recycled

CELL PROCESSING efficient cleaning and damage removal to reduce the use of process chemicals

process step: wafering

resource: kerf loss

impact: reduce resource use

process chemicals are polluting

efficient processing reduces required chemicals

resource reduction

silver fingers are expensive

new printing technology allows for thinner fingers

resource reduction

DI water is lost during rinsing

DI water is recycled within the process

resource reduction

new contact need less silver due to new printing technology

new technology allows for printing smaller silver fingers

48

Silver

Si feedstock

Argon purge gas

crucibles

Si ingot

DI water

process chemicals

process organics

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low process efficiency

difficult disassembly

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

Aluminium

PROCESS INPUTS

PROBLEMS

innovative module design

module assembly

re-use DI water

easy disassembly

sealing modules

use Si-kerfloss in Li-ion batteries

process efficiency

no material degradation

energy efficiency

testing

repair

diagnostics

installation

end of life

enhanced disassembly

PRODUCTION CHAIN recycling

ECOSOLAR STRATEGIES re-use Argon purge gas

IMPACT

reduced resource consumption

component re-distribution

reduced energy consumption

copper recycling

re-use of glass

external use

49

IV

MODULE (DIS)ASSEMBLY INNOVATIVE MODULE DESIGN FOR DISASSEMBLY AND RECYCLING After completion of the cells, they are electrically series connected and assembled into a solar module. Moreover, a junction box is attached that will ensure suitable power output. Within current solar modules technology, one big eco-challenge is the fact all module components are physically linked to each other by lamination and soldering.

The only potential for recycling are destructive processes that result in lower grade materials in form of granules. Current PV modules also contain a vast amount of organic materials (EVA for encapsulation, PVF in back sheets).

As Apollon Solar’s NICE-modules are already designed for disassembly, in Eco-Solar Apollon focused on further reduction of the module BOM (Bill Of Materials) focusing on a frameless version of the PV module, and integration of electronics in the junction box, to monitor the performance in the field. Moreover, Apollon demonstrated that module assembly of the Eco-Solar cells will result in comparable module output as with current non-eco-friendly state of the art module technology.

Finally, Apollon Solar demonstrated the disassembly of modules into their major components (glass sheets, copper wires, cells) allowing for their recovery as entire pieces with a high added value and strong potential for re-use (in PV or other industries).

The benefits of material savings will be demonstrated via the LCA carried out by bifa.

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controlled disassembly prevents high energy consumption and material degradation

module can be easily disassembled due to underpressure technology

MODULE (DIS)ASSEMBLY

front glass, re-used in new modules

no Aluminium frame due to glass/glass and double edge sealing

cell contacts, silver is re-used

process step: module (dis)assembly

resources: Aluminium, Copper, Silver, glass, cells

impact: reduce resource use/ degradation/ energy consumption

modules are closed by encapsulants

this leads to high energy consumption and material degradation

modules are vacuum sealed

modules can easily be taken apart

individual components are sorted and re-used

hazardous encapsulants are not needed

pure copper wires, copper is re-used

cells can be scanned, repaired and re-used

cells can be etched or melted

no encapsulant, neutral gas instead

back glass, re-used in new modules

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Silver

Si feedstock

Argon purge gas

crucibles

Si ingot

DI water

process chemicals

process organics

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low process efficiency

difficult disassembly

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

Aluminium

PROCESS INPUTS

PROBLEMS

innovative module design

module assembly

re-use DI water

easy disassembly

sealing modules

use Si-kerfloss in Li-ion batteries

process efficiency

no material degradation

energy efficiency

testing

repair

diagnostics

installation

end of life

enhanced disassembly

PRODUCTION CHAIN recycling

ECOSOLAR STRATEGIES re-use Argon purge gas

IMPACT

reduced resource consumption

component re-distribution

reduced energy consumption

copper recycling

re-use of glass

external use

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V

CELL REPARATION ECOLOGICAL AND ECONOMIC ASSET A small fraction of the finished solar cells (about 2%) contains electrical defects and can therefore not be used for module assembling. There is in practice no solution available for such cells, other than scrapping. Besides that an additional 2% contain hidden defects, which will develop cracks and other defects early in their use, probably during their handling and mounting in the modules, or early in their service.

Another approximate 4% of cells initially produced as prime or class B, have to be downgraded to their selling due to small fabrication defects. These cells are fully functional, but have lower efficiency and lifespan, hindering their lifecycle ecological balance: energy produced over energy, carbon, material and chemicals used in producing it.

Therefore, to capitalise on the value a solar cell represents, repair of defect solar cells within the solar cell process can represent a significant financial and ecological impact.

AIMEN coordinated the EU-funded project REPTILE, in which ISC and INGESEA participated as beneficiaries. The project provided preliminary work on a system that is able to automatically select and cut out or isolate non-defective areas in defective cells and wafers, called the CellDoctor.

ISC evaluated rejected solar cells with an automated system for defects recognition.

AIMEN and INGESEA further developed the accuracy of the Cell-Doctor prototype, aiming to avoid 50% scrapped cells. Moreover, this technology can be used to evaluate solar cells after end-of-life modules return to the factory for recycling and reuse.

In an LCA, bifa assessed the environmental benefits of the repair process for solar cells.

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cells are diagnosed to identify the scope and location of the damage

a laser treats the affected spots, removing damage

3

2

4

1

solar cell supply

robot arm carefully transports individual cells

CELL REPARATION a flash test determines how succesful the treatment has been

fully integrated reparation and testing process

process step: reparation

resource: solar cells

impact: reduce resource use

solar cells are checked for defects

laser treatment is used to remove defective spots

repaired cells can be re-utilized

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Silver

Si feedstock

Argon purge gas

crucibles

Si ingot

DI water

process chemicals

process organics

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low process efficiency

difficult disassembly

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

Aluminium

PROCESS INPUTS

PROBLEMS

innovative module design

module assembly

re-use DI water

easy disassembly

sealing modules

use Si-kerfloss in Li-ion batteries

process efficiency

no material degradation

energy efficiency

testing

repair

diagnostics

installation

end of life

enhanced disassembly

PRODUCTION CHAIN recycling

ECOSOLAR STRATEGIES re-use Argon purge gas

IMPACT

reduced resource consumption

component re-distribution

reduced energy consumption

copper recycling

re-use of glass

external use

57

VI

LIFE CYCLE ASSESSMENT PROCESS ANALYSIS AND ENVIRONMENTAL IMPACT To be able to determine the actual environmental impact of the Eco-Solar results, a thorough ecologic validation is necessary. Moreover, the only chance for implementing eco-friendly production methods is when they are economically viable. Therefore, it is of crucial importance that all processes are assessed for their economic viability and that the recovered waste products find (new) markets, where they can purposefully be introduced as (new) resources.

When writing the grant application, it became obvious that current literature does not provide consistent data to fully calculate ecologic impact of reducing materials in certain process steps. Moreover, different market forecasts for PV-growth give additional uncertainty. Therefore, within the Eco-Solar project, bifa carried out a Life-Cycle Inventory, based on data from the partners and published data. bifa will monitor and validate the achievements, using state of the art LCA and LCI methodologies.

Moreover, bifa supported partners in finding alternative uses for their waste products.

This recycling and repurposing of advanced materials will address argon purge gas, graphite hot-zone parts from the crystallisation furnaces, Si-kerf-loss, silica crucibles, water, steel wires from the saw, silicon nitride crucibles, solar cells and modules. A strength of the eco-efficiency analysis is the simultaneous optimization of economic and ecological aspects that can be used to identify the most promising development routes and products.

It will also be applied to develop recycling processes that allow the highest possible recycling yield and quality that will be feasible from an economic point of view for the individual materials used in production and products. The eco-efficiency analysis starts with setting the system boundaries and defining the processes. After that the collection of environmental and economic data starts, the life cycle inventory is built up and the LCA is carried out on the impact categories agreed on in the definition phase. Environmental key performance indicators can be calculated after normalization and weighing. This will also be used together with the cost analysis to build the eco-efficiency portfolio,

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59

no need for Aluminium frame due to sealing technology crystallization

recycling Argon

front glass, re-used in new modules

re-using crucibles

wafering recycling Si kerf cells can be etched or melted

cells can be scanned, repaired and re-used

re-using in batteries

cell processing

reducing use of Silver reducing use of process chemicals re-using Di water

cell contacts, silver is re-used

repairing cells module assembly

wires, copper is re-used

re-using components recycling components

encapsulants are no longer needed recycling module can be easily disassembled due to vacuum technology

recycling and re-using source materials

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P RO J E CT O V E RV I E W Si feedstock

Silver

Argon purge gas

crucibles

Si ingot

DI water

process chemica

Argon purge gas is vented

crucibles break

Si-kerfloss is unutilized

DI water use by rinsing

low proc efficienc

crystallization

wafering

cell processing

re-use crucible

re-use Si-kerf loss

re-use DI water

easy dis

use Si-kerfloss in Li-ion batteries

process efficiency

no mate degrada

testing

repair

diagnos

PROCESS INPUTS

PROBLEMS

innovat module

PRODUCTION CHAIN

ECOSOLAR STRATEGIES re-use Argon purge gas

s als

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process organics

cess cy

difficult disassembly

tive e design

module assembly

sassembly

sealing modules

erial ation

energy efficiency

stics

Aluminium

installation

end of life

recycling

copper recycling

re-use of glass

reduced resource consumption

enhanced disassembly

external use

component re-distribution

reduced energy consumption

62

IMPRINT SINTEF

APOLLON SOLAR

AIMEN

Martin Bellman (coordinator)

Roland Einhaus

Tamara Delgado García

Anu Schei

Frédéric Madon

Francisco Rodriguez Lorenz

Nils Peter Wagner

Pablo Romero Romero

NORSUN

GARBO

STEULER

Gyou Seong Park

Gianluigi Noja

Arjen Ciftja

Ilaria Lombardi

Rune Roligheten Jan D. Sandmo

SOLITEK

BOUKJE.COM

INGESEA

Valius Čyras

Karen van den Bos

Axier Bollar

Julius Denafas

Boukje Ehlen

Ane Miren Iriondo

Povilas Lukinskas

Otto Paans

Lina Petrèniené ISC KONSTANZ

BIFA

Florian Buchholz

Iris Fechner

Stephan Eisen

Boris Mertvoy

Elina Schmid

René Peche

Eckard Wefringhaus

Matthias Seitz Karsten Wambach

Graphics by Boukje.com Consulting BV (c) 2016–2023

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IMPRINT This project has received funding

Grant agreement no: 679692

from the European Commission in the H2020 program.

H2020-FoF-2015

2015–2018

FoF-13-2015 Re-use and remanufacturing technologies and equipment for sustainable product lifecycle management

project partners

E C O S O LAR 2 0 1 5 - 2 0 1 8

E U R O P EAN UNION

H O R I Z ON2 0 2 0