Standard Printing Techniques Pushing the Envelope to 75 mg ... · Standard Printing Techniques –...
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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
Page 5
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
Page 7
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
Page 8
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
Page 11
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
Page 14
52 µm
C. Muschelknautz | HPM-TFD-PV | May 7th 2013
Silver Usage per Cell
Page 15
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