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Saving silver in screen printed solar cell processing
Ecosolar
WP 3: Remanufacturing, resource efficiency and reuse in solar cell
processing
Dr. Florian Buchholz
[email protected]; +49 7531 36 183 553
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Silver demand and costs
2
https://www.caseyresearch.com/articles/a-photovoltaic-silver-bull-in-china; July 29, 2013
5.6%
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Silver demand and costs
3
https://www.bullionvault.com/gold-news/silver-solar-050420163
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Share of world wide silver
consumption
4
https://www.bullionvault.com/gold-news/silver-solar-050420163
Almost
15% of
total silver
demand
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Silver consumption per module
5
ITRPV
J. Trube, SNEC 2017
State of the art: 6 g / 60 cell module
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Content
6
Introduction of Ecosolar WP3
Status quo of solar cell metallization
Approaches towards saving of silver
Solar cell concepts
First experimental results
Summary and outlook
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
7
Introduction of Ecosolar WP3
Status quo of solar cell metallization
Approaches towards saving of silver
Solar cell concepts
First experimental results
Summary and outlook
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Overall objectives
Less energy consumption during processing compared to standard solar cell
process due to higher material throughput
Manufacturing processes to enable the use of fewer material resources such
as Ag and Pb
Advanced cell processes for reduction of chemicals consumption (wet
acids)
Demonstration of the potential for process water recycling
8
Introduction of Ecosolar WP3
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Introduction of Ecosolar WP3
9
Goals
LCI State of the
art: 6.47g
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
10
Introduction of Ecosolar WP3
Status quo of solar cell metallization
Approaches towards saving of silver
Solar cell concepts
First experimental results
Summary and outlook
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Status quo of solar cell metallization
11
ITRPV Eighth Edition 2017
Screen printing likely to dominate for the next ten years
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Status quo of solar cell metallization
12
Screen printing state of the art
Backside metallization Numbers of busbars
Changes in PV industry only gradually.
non-disruptive gradual improvement of existing technology
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
pitch numbers of BB finger width
BB width/design paste …
Screen printing state of the art: co-optimization problem
Status quo of solar cell metallization
13
•cell concept
•emitter sheet
resistance
•doping
surface
concentration
•surface
morphology
•classifier setup
•module
technology
•stringer
technology
Front end Back end
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Galiazzo (Applied Materials) Metallization Workshop 2016
Improve finger quality (aspect ratio, reduce thickness)
Advantages
• Lower shading, higher currents
Disadvantages
• Requires advanced screen, paste and
printing technology
• May require extra printing steps
Leave out busbars / rear side pads
Advantages
• Low hanging fruit
Disadvantages
• Requires special classifier setup
• Requires new methods for interconnection
Approaches towards saving of silver
14
Dauwe (H.A.L.M.) Metallization Workshop 2016
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
15
Introduction of Ecosolar WP3
Status quo of solar cell metallization
Approaches towards saving of silver
Solar cell concepts
First experimental results
Summary and outlook
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Solar cell structures
16
Standard Al BSF mc solar cells
by SoliTek
BiSoN cells by ISC Konstanz
Eta = ~ 18%
Ag paste lay down:
135 – 145 mg (industrial production)
3 printing steps
Eta = ~ 21%
Ag paste lay down:
309 – 322 mg (lab scale production)*
~ 200 mg (industrial production)
3 printing steps
Silver content finger paste: ~ 80%
Silver content pad paste: ~ 50%
*State of the art: 240 mg
Ag BB (Pad paste)
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Content
17
Introduction of Ecosolar WP3
Status quo of solar cell metallization
Approaches towards saving of silver
Solar cell concepts
First experimental results
Summary and outlook
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
First experimental results
18
Improve finger quality (Front side of BiSoN-cells)
BKM:
1st print: fingers, screen opening 45 µm
2nd print: busbars (4BB, 1.5 mm)
Possibility 1: Double print
1st print: fingers screen opening 30 µm
2nd print: fingers and busbars (32µm finger opening)
Possibility 2: Fineline print
1st print : fingers screen opening 30 µm
2rd print: busbars (4BB, 1.5 mm)
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
First experimental results
19
Paste lay down front side metallization
Group Fingers Busbars Relative paste amount
BKM 94-96 mg 47-53 mg -
Double print 40-45 mg 56 mg ~ 0.7
Fineline 40-45 mg 47-53 mg ~ 0.65
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
First experimental results
20
BKM:
Double:
Fineline
30µm:
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
First experimental results
21
Finger measurements
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
First experimental results
22
Solar cell parameters
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
First experimental results
23
Improve finger quality (aspect ratio, reduce thickness)
Current paste generation can be used for fineline printing
Fineline printing yields similar solar cell efficiencies
Double print requires well-matching screens and highly accurate optical
recognition (update of printer system may be necessary)
It, however, may increase solar cell efficiencies
Reduction of up 34 % of paste laydown
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Leave out busbars / rear side pads
BiSoN cells without BB on the back side were manufactured
Pad-paste on front side was also varied and tested
No IV-data could be obtained (measurement setup for no-BB cells is currently
set up)
Solar cells were soldered and glued into mini-modules (one cell)
TC200 testing in climate chamber was performed
24
First experimental results
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
25
FF results of cells glued and printed
Good contacting with both methods
First experimental results
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
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FF results of cells glued and printed
Similar degradation behavior
First experimental results
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
27
Introduction of Ecosolar WP3
Status quo of solar cell metallization
Approaches towards saving of silver
Solar cell concepts
First results
Summary and outlook
Florian Buchholz, June 8th 2017
Eco-Solar [679692]
Summary and Outlook
28
Screen printing is here to stay
Silver reduction necessary
Lower paste laydown also reduces consumption of lead
Promising approaches for printing optimization: double / fineline print
Busbars in principle can be left out
Several down-turns:
• measuring
• long term stability has not been shown
• large scale integration potential has not been shown
we will test no-BB cells with Apollon NICE module approach in the Ecosolar
project
Thank you for your attention
and special thanks to the ISC team and in particular Pirmin Preis and Dominik Rudolph for
their valuable input.
Dr. Florian Buchholz
[email protected]; +49 7531 36 183 553
![10.2 Attractiveness criteria for remanufacturing in ... · remanufacturing process is assigned to the low automation of the process [18]. Core acquisition . Another challenge to remanufacturing](https://img.dokumen.tips/doc/110x75/5f2b3ad3b4bcda5693165ad5/102-attractiveness-criteria-for-remanufacturing-in-remanufacturing-process.jpg)
