Investigation on N-PERT Bifacial Solar Cell and Module Celltech... · 2017-03-27 · Investigation...
Transcript of Investigation on N-PERT Bifacial Solar Cell and Module Celltech... · 2017-03-27 · Investigation...
Investigation on N-PERT Bifacial
Solar Cell and Module
Dr. Feng Li
Deputy General Manager of Technology Center
Yingli Energy (China) Co., Ltd
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Outline
2 N-PERT SBSF Cell Investigation
3 PANDA Cell Module
4 Summary
Slective back surface field(SBSF) solar cell 1 PANDA-N-PERT Cell
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N-PERT Cell
Diffusion / Ion Implantation
Edge Isolation
SiN Passivation /
ARC Coating
Drying & Firing
Texture
SP Al / Ag
B and P diffused regions made by
different technologies (two diffusions,
co-diffusion using doped glasses, ion
implantation with anneal)
Most of existing P-type Si cell process
technology can be used
Passivation
Passivation
18.0%
18.5%
19.0%
19.5%
20.0%
20.5%
21.0%
21.5%
2009 2010 2011 2012 2013 2014 2015 2016 2017
Yingli Panda Cell Efficiency
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PANDA - N-PERT Cell
CZ N-Si Substrate
Front contact
Rear contact (Ag)
Incident
light
Incident
light Textured front surface with antireflection coating
Boron diffused emitter (P+)
Textured front surface with antireflection coating
Boron diffused emitter (P+)
Phosphorus diffused BSF
SiNx passivationcoating
Simple cell structure and easy manufacture
Cost-effective production steps and compatible with existing production lines
Sun-light can be accepted by double sides, produce more electricity
Excellent anti-LID performance
Front
Four Busbars
Metallization
Ion
implantation
Double
Printing
Rear
Polishing
Rear
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N-PERT SBSF Cell Investigation
Conventional back surface field Selective back surface field (SBSF)
Low contact resistance
High back surface recombination
velocity
Low contact resistance
Low back surface recombination
velocity
ARC:SiO2/SiNx
N-type Substrate
(P+) emitter
N+ BSF
n++ n++ n++
Back contact(Ag)
Front contact(Ag/Al) ARC:SiO2/SiNx
N-type Substrate
(P+) emitter
N+ BSF
Back contact(Ag)
Front contact(Ag/Al) ARC:SiO2/SiNx
ARC:SiO2/SiNx
Sample
preparation
Test procedre
N-type Substrate
(P+) emitter
N+ BSF
n++ n++ Depth
Mask Width
Depth
BSF passivation
Voc Jsc FF
Efficiency
Mask width
Alignment
N-PERT SBSF Cell Investigation
Voc Jsc FF
Efficiency
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BSF doping profile Sheet resistance Vs. etching time
Thermal treatment has great impact not only on the Rsheet but also on the
doping profile
Increasing rate of Rsheet is related to the doping profile
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
1E15
1E16
1E17
1E18
1E19
1E20
1E21
surf
ace
phosp
hours
conce
ntr
atio
n(a
tom
s/cm
3)
Depth(um)
POCl3 diffusion 40Ω/sq
POCl3 diffusion 16Ω/sq
0 1 2 3 4 5 6 7 8 9 10
0
20
40
60
80
100
120
140
160
180
200
220
240
Rsh
(Ω/s
q)
Etch time(min)
POCl3 diffusion 40Ω/sq
POCl3 diffusion 16Ω/sq
N-PERT SBSF Cell Investigation
Doping and etch back
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10 20 30 40 50 60 70 80
650
652
654
656
658
660
662
664
Voc
Jsc
Rsh(Ω/sq)
Voc(
mV
)
38.0
38.2
38.4
38.6
38.8
39.0
Jsc
(mA
/cm
2)
10 20 30 40 50 60 70 80
79.0
79.5
80.0
80.5
81.0
FF
Eff
Rsh(Ω/sq)F
F(%
)
20.0
20.1
20.2
20.3
20.4
20.5
Eff
icie
ncy
(%)
Suitable etching depth has to be selected for balancing the Voc, Jsc
and FF that have great effect on the final cell efficiency
Cell parameters Vs. Rsheet
N-PERT SBSF Cell Investigation
Group Mask width(um) Voc(mV) Jsc(mA/cm2) FF(%) Eff(%)
G1 6a 657 39.17 80.73 20.78
G2 5a 659 39.21 80.66 20.84
G3 4a 661 39.26 80.65 20.93
G4 3a 660 39.30 80.62 20.91
Etch back Metalization 9
N-PERT SBSF Cell Investigation
Mask width optimization
Group Finger
number
Mask
width(um)
Voc
(mV)
Jsc
(mA/cm2)
FF
(%)
Eff
(%)
G1 Normal N-PERT 653 38.85 80.43 20.40
G2 n1 A1 662 39.35 79.54 20.72
G3 n2 A2 661 39.31 80.12 20.83
※Same mask area for G2 and G3
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N-PERT SBSF Cell Investigation
Mask width optimization
77.5
78.0
78.5
79.0
79.5
80.0
80.5
81.0
81.5
82.0
G3G2
G1
G2
G3
FF
(%)
G1
Group Voc (mV) Jsc (mA/cm2) FF (%) Eff (%)
N-PERT Cell 656 38.98 80.95 20.70
SBSF Cell 662 39.62 80.91 21.22
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N-PERT SBSF Cell Investigation
Cell performance comparison
400 500 600 700 800 900 1000 1100 12000.0
0.2
0.4
0.6
0.8
1.0
IQE
Wavelength(nm)
Panda Cell
SBSF Cell
19.5 20.0 20.5 21.0 21.5
5%
10%
15%
20%
25%
30%
N-PERT Cell
N-PERT SBSF Cell
Cell efficiency(%)
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N-PERT SBSF Cell Investigation
Cell Parameters Area(cm2) Voc (mV) Jsc(mA/cm2) FF(%) Eff(%)
Front Side 244.3 664.3 40.01 80.95 21.52
Rear Side 244.3 661.6 36.53 80.87 19.54
0
1
2
3
4
5
6
0
1
2
3
4
5
6
7
8
9
10
0 0.2 0.4 0.6 0.8P
ow
er
(w)
Cu
rre
mt
(A)
Voltage (V)
Front side I-V Curve
0
1
2
3
4
5
6
0
1
2
3
4
5
6
7
8
9
10
0 0.2 0.4 0.6 0.8
Po
we
r (w
)
Cu
rre
mt
(A)
Voltage (V)
Rear side I-V Curve
Typical cell parameters
Bifaciality factor > 90%
LID characteristics
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Excellent anit-LID performance
PANDA Module
PROPRIETARY AND CONFIDENTIAL
Gain of power output from Panda module compared to traditional mono c-Si solar cell module
One Month Data
Average Gain of Power Output Maximum Gain of Power Output
20.20% 33%
PANDA Module
0
2
4
6
8
10
12
14
16
0%
5%
10%
15%
20%
25%
30%
35%
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Rad
iati
on
of
titl
ed
su
rface
(k
Wh
/m2)
Po
wer
Gain
(%
)
Generating Test
Power Gain
Radiation of titled surface (kWh/m^2)
PANDA Module
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Power output collection for 1 year with installed modules on a bright rooftop
The distance from module to the ground of 30 cm
The test result shows the Panda module average power output is 21% higher
than normal module .
STC power
output
increased
5% 10% 15% 20% 25% 30%
290 W 304 W 319 W 333 W 348 W 362 W 377 W
Power output gain comparison
Power gain under different reflective conditions
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Sand/Gray Cement Snow Field Grassland Bright Rooftop
PANDA Module
10% power output gain at the ground and grassland with reflectivity of 25%
15% power output gain at the Sand/gray cement floor with reflectivity of 50%
25% power output gain at the bright rooftop with reflectivity of 78%
30% power output gain at the snowfield with reflectivity of 90%
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PANDA Module
Panda Module Normal Module
Panda Module Normal Module
Self-cleaning function
Summary
YINGLI N-PERT bifacial cell with SBSF structure have already reached
efficiency of 21.52%, and 19.54% on rear side.
There are still many rooms to improve the N-PERT solar cell performance
such as doping, passivation and metallization. Manufacturing technique
aiming to 22% efficiency of N-PERT cell with bifaciality > 95% is under
investigation and will be realized at YINGLI soon.
YINGLI PANDA module with excellent anti-LID performance provides 10%
- 30% output gain compared to monofacial module depending on ground
reflective conditions.
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