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Validating IEC TS 63209 - Colin Sillerud

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Colin Sillerud
CFV Labs
Albuquerque, NM
2021-12-08
Validating IEC TS 63209-1 Mechanical
and Backsheet Degradation Test Legs
Outline
Introduction:
• Overview of IEC TS 63209-1
Test legs of interest and why:
• MLT
• UV
Conclusion:
Future Testing:
IEC TS 63209-1
Photovoltaic
Modules –
ExtendedStress Testing
• IEC TS 63209-1 is the first IEC specification for extended
PV module reliability testing
• Designed to be utilized with existing equipment and
accepted IEC test methods
• Allows for the standardization of extended testing for
inter-comparability of results
IEC TS 63209
Development
Partners
IEC TS 63209-1:
Test Flow
IEC TS 63209
Mechanical
Stress Testing
Sequence:
Target for
Mechanical
Stress Testing
Design extended mechanical stress sequence that
more closely matches field results
Fielded Module
• Cell cracking
• Electrical
isolation
• Performance
loss primarily in
Imp and Pmp
Stress
Fielded
Isc (A)
-0.80%
Voc (V)
-0.65%
Imp (A)
-15.21%
Vmp (V)
-3.03%
Pmp (W)
-17.73%
Design of Experiment
Leg 1 (DMLT - Baseline)
Leg 2 (Static MLT)
Leg 3 (SMLT+DMLT)
Leg 4 (No MLT - Reference)
Stabilization
Stabilization
Stabilization
Stabilization
SMLT (+/-2400 Pa)
SMLT
DMLT (+/-1000 Pa)
DMLT
TC50
TC50
TC50
TC50
HF10
HF10
HF10
HF10
MTL Test Setup
Characteristic
Module Type A
Module Type B
Cell Type
5BB Mono-PERC
4BB Mono-PERC
Cell Count
72
72
Frame Thickness
<35 mm
40 mm
Power Class
350 W
360 W
Construction
G/B
G/B
Center Deflection
at +2400 Pa
47 mm
32 mm
9
DMLT
Results – EL
Imaging
(Module
Type A)
• Minimal cracking (4-7
cells)
• Electrical isolation
SMLT
• Cracking (7-16 cells)
• Minimal electrical
isolation
SMLT+DMLT
• Cracking (12-13 cells)
• Electrical isolation
Result:
• SMLT+DMLT better
approximation of
fielded samples
DMLT
SMLT
SMLT+DMLT
Field Comparison - Electroluminescence
Fielded Module
SMLT
SMLT + DMLT
20
Type A (SMLT+DMLT)
Results – EL
Imaging
(Comparison:
Module Type
A / Type B)
• Cracking (12-13 cells)
• Electrical isolation
Type B (SMLT+DMLT)
• Cracking (7-11 cells, but
smaller segments)
• Electrical isolation
Result
• Test shows relative difference
in isolated area between
module types produced by
mechanical stress
Type A
Type B
Results – Performance
Performance Change (Pmp) Type B
1
1
0
0
-1
-1
Control
-2
DMLT
-3
SMLT
SMLT + DMLT
-4
-5
Percent Change (%)
Percent Change (%)
Performance Change (Pmp) Type A
No MLT
-2
DMLT
-3
SMLT
SMLT + DMLT
-4
-5
-6
-6
Static MLT
Dynamic MLT
TC50
HF10-1
Static MLT
Dynamic MLT
• Resulting power loss over sequence between type A and B nearly
identical (~ -5%)
• Power loss on type A depends on sequence - SMLT+DMLT is largest
• Power loss on type B is sequence independent
• Type A exhibits greater damage via EL. Why is the power change
the same?
TC50
HF10-1
Type B - Current Change (Imp)
1
0
0
-1
No MLT
-2
DMLT
SMLT
-3
SMLT + DMLT
-4
Percent Change (%)
1
-5
-1
No MLT
-2
DMLT
SMLT
-3
SMLT + DMLT
-4
-5
Static MLT
Dynamic MLT
TC50
HF10-1
Static MLT
Type A - Current Change (Isc)
1
1
0
0
-1
No MLT
-2
DMLT
SMLT
-3
SMLT + DMLT
-4
-5
Dynamic MLT
TC50
HF10-1
Type B - Current Change (Isc)
Percent Change (%)
Percent Change (%)
Results –
Performance
with
Reference
Module
Percent Change (%)
Type A - Current Change (Imp)
-1
No MLT
-2
DMLT
SMLT
-3
SMLT + DMLT
-4
-5
Static MLT
Dynamic MLT
TC50
HF10-1
Static MLT
Dynamic MLT
TC50
HF10-1
Type A
Type B
• Imp loss corelates with loss in
active cell area and string
mismatch of module
• Imp and Isc change are nearly
identical hinting at loss in light
capture of whole module
• Isc shows little change
• Is there a non-mechanical
degradation occurring?
Possible AR
Coating
degradation –
HF10
Results – Performance with Reference Module
Type B - Performance Change (Pmp) Normalized by
Reference
1.00
1.00
0.00
0.00
-1.00
DMLT
-2.00
SMLT
SMLT + DMLT
-3.00
-4.00
Percent Change (%)
Percent Change (%)
Type A - Performance Change (Pmp) Normalized by
Reference
-1.00
DMLT
-2.00
SMLT
SMLT + DMLT
-3.00
-4.00
-5.00
-5.00
Static MLT
Dynamic MLT
TC50
HF10-1
Static MLT
Dynamic MLT
TC50
• Performance results normalized by Reference module (No MLT)
• Resulting power loss from mechanical stress:
•
•
Type A: -3.52 %
Type B: -0.92 %
• Type A is more susceptible to mechanical degradation than Type B
• SMLT+DMLT shows worst case mechanical degradation (cracks present and opened)
HF10-1
Fielded
SMLT+DMLT
Fielded
Field
Comparison –
Performance
Performance
loss primarily
in Imp matches
fielded
modules
SMLT+DMLT
Stress
Isc (A)
Voc (V)
Imp (A)
Vmp (V)
Pmp (W)
SMLT+DMLT
-0.92%
-0.58%
-5.36
-0.80
-6.10%
Fielded
-0.80%
-0.65%
-15.21%
-3.03%
-17.73%
Conclusion –
Mechanical
Leg
• DMLT not able to effectively crack cells in either module
type
• SMLT as crack initiator, DMLT as crack opener
• Able to examine relative differences between more or
less crack-resistant module designs
• Performance loss in Pmp and Imp, consistent with loss of
cell collector area and an increase in cell to cell mismatch
• Reference module is required to correctly interpret
results, due to possible degradation from TC50/HF10
alone.
IEC TS 63209
UV Backsheet
Testing
Sequence:
Validate IEC TS 63209 backsheet testing sequence using
known bad and presumed good samples
Target for
Polymeric
Backsheet
Testing
• Backsheet
cracking on
fielded sample
from a
combination of
UV, temperature
and humidity
stresses
• Module level
testing for BOM
specific concerns
Results: Visual
Inspection
Failures in Both
Older and Newer
Backsheets
Module
Construction
Matters
Sample Group 1
Sample Group 2
Sample Group 3
Sample Group 4
AAA (known bad)
PVDF-1
PVDF-1
PET
Standard Busbar
Multi-Wire Busbar
Standard Busbar
Multi-Wire Busbar
Full cell (72)
Half-cut (144)
Full cell (72)
Half-cut (144)
2013 – Mnfr. 1
2018 – Mnfr. 2
2018 – Mnfr. 3
2018 – Mnfr. 2
Pass
Pass
Pass
Pass
Pass
Pass
FAIL - Backsheet Cracking FAIL - Backsheet Cracking
(Behind avg. 30% of cells)
(Behind avg. 100% of cells)
Pass - Wet Leakage
Pass - Wet Leakage
FAIL - Backsheet Cracking
-
-
(Behind avg. 28% of cells)
Pass
Pass - Wet Leakage
-
-
-
Pass
Backsheet
Durability Test
Results:
Conclusion
IEC TS 63209
UV Sequence
Provokes
Failures in
Past and Current
Backsheets
• Testing able to reproduce field
relevant failures
Results:
AAA (Fielded ~ 8
years)
AAA (Manuf. 2013,
2 cycles 63209)
PVDF (Manuf. 2018,
2 cycles 63209)
PVDF (Manuf. 2018, 3
cycles 63209)
• Both known bad (AAA) and
modern materials (PVDF) fail
63209 accelerated tests that
correlate to 8-12 years of field
stress.
• Backsheet failures are moduleconstruction dependent.
• Same back sheet performed
differently on different
constructions
• Encapsulant chemistry and
thickness, cell interconnect
topography and other factors
affect backsheet durability.
Future Work
for IEC TS
63209-1
Enhancement
Front-Side UV
• No glass-side UV
testing in IEC TS
63209-1
• Propose development
of test for rapid (~6
month) front-side
field failure modes
Discoloration and drop in Pmp (-6%) on mono-PERC
after 6 months in field at CFV
Hail
• Hail is an increasing
concern, but no hail prestress in mechanical
degradation sequence in
63209-1
https://kubyenergy.ca/blog/solar-panels-vs-hail
Contact
Colin Sillerud
Email: colin.sillerud@cfvlabs.com
CFV Labs
5600-A University Blvd.
Albuquerque, NM 87106
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