Standard Printing Techniques Pushing the Envelope to 75 mg ... · Standard Printing Techniques –...

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Standard Printing Techniques Pushing the Envelope to 75 mg Paste per Cell C. Muschelknautz*, A. Henning, M. Deckelmann, A. Stassen, M. Hörteis Heraeus Precious Metals GmbH & Co. KG, Business Unit Photovoltaics, Heraeusstr. 12-14, 63450 Hanau, Germany

Transcript of Standard Printing Techniques Pushing the Envelope to 75 mg ... · Standard Printing Techniques –...

Standard Printing Techniques – Pushing the Envelope to 75 mg Paste per Cell

C. Muschelknautz*, A. Henning, M. Deckelmann, A. Stassen, M. Hörteis

Heraeus Precious Metals GmbH & Co. KG, Business Unit Photovoltaics, Heraeusstr. 12-14, 63450 Hanau, Germany

Outline

Advantages of Silver

Silver in PV Industry over the Last Years

Approaches to Decrease Silver Consumption

Take Home Message

C. Muschelknautz | HPM-TFD-PV | May 7th 2013 Page 2

Reasons to Use Silver in Metallization Pastes

Page 3

pros cons

used and proven for more than 30

years

price of silver

best conductor ???

good contact with Si

robust process

chemically and physically stable

element (precious metal)

continuous improvements in efficiency

and in price reduction

C. Muschelknautz | HPM-TFD-PV | May 7th 2013

Silver Price over Time

http://heraeus-edelmetallhandel.de/en/industriekunden/service_1/test_charttool.aspx

Page 4 C. Muschelknautz | HPM-TFD-PV | May 7th 2013

48.7 $/oz

24.2 $/oz

Silver Usage per Cell

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best practice

graph of ITRPV (2012)

reduction in use much faster than predicted

screen printing more sustainable than expected

ITRPV numbers 2013

C. Muschelknautz | HPM-TFD-PV | May 7th 2013

0

200

400

600

800

1000

1200

1400

1600

1800

2003 2005 2007 2009 2011 2013

Sil

ve

r u

sa

ge

in

PV

(to

n)

0

5

10

15

20

25

30

35

40

an

nu

al P

V p

rod

ucti

on

(G

Wp

)

Total Amount of Silver Used by PV

amount of GWp increases each year

percentage of screen printed cells increased in 2012

reduction since 2010 due to lower use per wafer

Page 6 C. Muschelknautz | HPM-TFD-PV | May 7th 2013

Cost of Front Side Silver per Wp

average cost per Wp:

price of silver

paste consumption

efficiency of solar cell

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0

1

2

3

4

5

6

7

8

0

10

20

30

40

50

60

1-09 7-09 1-10 7-10 1-11 7-11 1-12 7-12 1-13 7-13

silver $/oz (Basis London fixing) cost of silver $c/Wp 3

.7c

4.9

c

7.2

c

5.9

c

4.4

c

2.9

c

2.8

c

1.9

c

decreased cost for front side

metallization despite higher silver

price

C. Muschelknautz | HPM-TFD-PV | May 7th 2013

How to Reduce Silver Consumption

improving materials:

improved contacting

improved sintering

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how to reach that goal from a paste point of view:

C. Muschelknautz | HPM-TFD-PV | May 7th 2013

How to Reduce Silver Consumption

improving application:

narrower finger width

improved uniformity

better aspect ratio

Page 9 C. Muschelknautz | HPM-TFD-PV | May 7th 2013

52µm 63µm

2009 2010 2011 2012

Trend in Finger Opening

finger opening

state of the art: 45-60 µm

trend: 35-40 µm

Author | Department | Date Page 10

wire diameter :

state of the art: 18 µm

trend: 14-16 µm

50 µm

30 µm 30 µm

paste: SOL9610A

wafer: 95 Ohm/square, 156 x 156 mm, full square

Experimental Setup

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parameter reference screen screen stencil

finger opening 60 µm 40 µm

finger count 74 82

bus bar count 3

bus bar width 1.5 mm

mesh 400c 380c -

wire diameter 18 µm 14 µm -

emulsion over mesh 17 µm 10 µm

hybrid no yes

C. Muschelknautz | HPM-TFD-PV | May 7th 2013

IV-Data SOL9610A

Page 12 C. Muschelknautz | HPM-TFD-PV | May 7th 2013

finger # Jsc [mA/cm2] Rgrid [mOhm] silver [mg]

60 µm screen 74 37.08 46 146

40 µm screen 82 37.49 79 85

40 µm stencil 82 37.55 65 87

60 µm screen 40 µm screen 40 µm stencil70

80

90

100

110

120

130

140

150

sil

ve

r [m

g]

40

60

80

Rg

rid

[m

Oh

m]

60 µm screen 40 µm screen 40 µm stencil37,0

37,1

37,2

37,3

37,4

37,5

37,6

Js

c [

mA

/cm

2]

40

60

80R

gri

d [

mO

hm

]

IV-Data SOL9610A

higher efficiency despite lower silver usage

efficiency gain by almost 0.2 % using 40 wt% less silver

Helge Hannebauer, ISFH Hameln, PERC cell with less than 70 mg paste

Page 13 C. Muschelknautz | HPM-TFD-PV | May 7th 2013

60 µm screen 40 µm screen 40 µm stencil18,3

18,4

18,5

18,6

18,7

18,8

Eta

[%

]

60

80

100

120

140

160

180

silv

er

[mg

]

Optimized Bus Bars for Stencil

segmented bus bar design pushes the paste consumption to 75 mg on the front

side maintaining the cell efficiency

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52 µm

C. Muschelknautz | HPM-TFD-PV | May 7th 2013

Silver Usage per Cell

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standard printing techniques on similar level as predicted for 2017

C. Muschelknautz | HPM-TFD-PV | May 7th 2013

Take Home Message

standard printing techniques are and will be the dominant metallization

technique for the next couple of years

good results with 85 mg silver on the front side as well with screen and stencil

optimized bus bar design decreases paste consumption to 75 mg on the front

side

decrease in silver consumption will be faster than predicted

Page 16 C. Muschelknautz | HPM-TFD-PV | May 7th 2013

Thanks to DEK Solar and Christian Koenen for the provision of screens and

stencils!

Thank you for your kind attention!

C. Muschelknautz*, A. Henning , M. Deckelmann, A. Stassen, M. Hörteis

Heraeus Precious Metals GmbH & Co. KG,

Thick Film Division Business Unit Photovoltaics, Herausstr. 12-14, 63450 Hanau, Germany

* Corresponding author, phone: +49 (0)6181 35 2327, Email: [email protected]

Page 17 C. Muschelknautz | HPM-TFD-PV | May 7th 2013