comparing accelerated testing and outdoor exposure · 2014. 1. 24. · mod module temperature t amb...
TRANSCRIPT
COMPARING ACCELERATED TESTING AND OUTDOOR EXPOSURE
Michael Koumlhl
Fraunhofer Institute for Solar Energy Systems ISE
3rd PV Rollout Conference Workshops ndash 2013
requirements for bankable pv modules
and pv power plants
Metro Atlanta Chamber USA - February 25th 2013
wwwisefraunhoferde
copy Fraunhofer ISE
Challengeslt
The durability is very good for most of the actual premium c-Si modules on the market (less than 1 loss in performance per year)
But new materials and designs have to be developed in order to decrease costs
bull Accelerated service life tests are needed for optimisation of the durability and convincing investors
bull The longer the desired lifetime the higher the needed acceleration factor the bigger the unsecurity of the tests
bull The tests should be based on real stress in the field because usually the materials and their degradation processes are not known
copy Fraunhofer ISE
Stress-factors at operation of PV-modules
Moisture causes hydrolysis and corrosion (Acetic acid from EVA)
Electrical potentials introduce leakage currents and reduction of cell efficiency
UV ndash irradiation causes destruction of polymeric components
Photo-degradation
Temperature cycling static oder dynamic mechanical loads lead to
Cell-breakage inter-connecture breakage delamination
Salt heat (high temperatures)
copy Fraunhofer ISE
Example for development of Accelerated Life Testingltbased on real stresses during operation of PV-moduleslt
Moisture causes hydrolysis and corrosion
Electrical potentials introduce leakage currents and reduction of cell efficiency
UV ndash irradiation causes destruction of polymeric components
Photo-degradation
Temperature cycling static oder dynamic mechanical loads lead to tensions
Cell-breakage inter-connecture breakage delamination
Salt heat (high temperatures)
copy Fraunhofer ISE
1 Monitoring climatic conditions Ambient climate and sample temperatures as 1min averaged time series
Corrosivity salt concentration as yearly or monthly dose
City or reference
Freiburg Germany
Alpine
Zugspitze
Germany
Arid
Sede Boqer
Israel
Tropical
Serpang
Indonesia (operated by TUumlV Rheinland
Maritime
Pozo Izquierdo
Gran Canaria
copy Fraunhofer ISE
Tamb
2 Monitoring micro-climatic stress factors
Module temperature monitoring during outdoor exposure
Macro ndash climate =gt Micro ndash climate
Ambient temperature Average module temperature (c-Si)
Tropics
temperature [degC] temperature [degC] -20 -10 0 10 20 30 40 50 60 70
0
200
400
600
800
1000
1200
1400
1600
-20 -10 0 10 20 30 40 50 60 0
200
400
600
800
1000
1200
1400
1600
frequ
ency
[h]
TavgDesert
Alpes
copy Fraunhofer ISE
v
3 Modeling micro-climatic stress factors Physical modeling of module temperature for each of the different module types using David
Faimanlsquos approach (could be King Fuenteshelliphellipas well)
Macro ndash climate =gt Micro ndash climate
Irradiation wind ambient temperature =gt Tmod
Neglected IR-radiation exchange and natural convection
HT T mod amb 10 UU v
Tmod module temperature
Tamb ambient temperature
wind velocity
H solar radiation
U1 U0 a-Si 1 107 257 a-Si 3 58 258 a-Si 4 43 261
CIS 1 31 230 CIS 2 41 250 CdTe 54 234 c-Si 62 300
The parameters U are module-specific but location independent
MKoehl etal Modelling of the nominal operating cell temperature copy Fraunhofer ISE based on outdoor weathering Sol Energy Mat Sol Cells (2011)
60
3 Modeling micro-climatic stress factors
Module-temperature as time-series based on ambient climate data and as histograms (one year)
tem
pera
ture
[degC
]
Tair5000
50
module
4000
3500
300040
Freu
ency
0 20 40 60 8
a-Si 1 a-Si 2 a-Si 3 a-Si 4 CIS 1 CIS 2 CdTe c-Si
T 4500
2500
2000
1500
1000
30
20 500
0 10
222 223 224 225 time [d] Temperature in degC
copy Fraunhofer ISE
Rel
wat
er c
once
ntra
tion
[au
]
3 Modeling micro-climatic stress factors
Simulation of module humidity by FEM
Damp-heat testing 85rh 85degC J Wirth Diplomarbeit Diploma Thesis University of Freiburg 20
copy Fraunhofer ISE J P Huumllsmann et alsu bmitted to Solar Energy MaterialsampSolar Cells
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
Challengeslt
The durability is very good for most of the actual premium c-Si modules on the market (less than 1 loss in performance per year)
But new materials and designs have to be developed in order to decrease costs
bull Accelerated service life tests are needed for optimisation of the durability and convincing investors
bull The longer the desired lifetime the higher the needed acceleration factor the bigger the unsecurity of the tests
bull The tests should be based on real stress in the field because usually the materials and their degradation processes are not known
copy Fraunhofer ISE
Stress-factors at operation of PV-modules
Moisture causes hydrolysis and corrosion (Acetic acid from EVA)
Electrical potentials introduce leakage currents and reduction of cell efficiency
UV ndash irradiation causes destruction of polymeric components
Photo-degradation
Temperature cycling static oder dynamic mechanical loads lead to
Cell-breakage inter-connecture breakage delamination
Salt heat (high temperatures)
copy Fraunhofer ISE
Example for development of Accelerated Life Testingltbased on real stresses during operation of PV-moduleslt
Moisture causes hydrolysis and corrosion
Electrical potentials introduce leakage currents and reduction of cell efficiency
UV ndash irradiation causes destruction of polymeric components
Photo-degradation
Temperature cycling static oder dynamic mechanical loads lead to tensions
Cell-breakage inter-connecture breakage delamination
Salt heat (high temperatures)
copy Fraunhofer ISE
1 Monitoring climatic conditions Ambient climate and sample temperatures as 1min averaged time series
Corrosivity salt concentration as yearly or monthly dose
City or reference
Freiburg Germany
Alpine
Zugspitze
Germany
Arid
Sede Boqer
Israel
Tropical
Serpang
Indonesia (operated by TUumlV Rheinland
Maritime
Pozo Izquierdo
Gran Canaria
copy Fraunhofer ISE
Tamb
2 Monitoring micro-climatic stress factors
Module temperature monitoring during outdoor exposure
Macro ndash climate =gt Micro ndash climate
Ambient temperature Average module temperature (c-Si)
Tropics
temperature [degC] temperature [degC] -20 -10 0 10 20 30 40 50 60 70
0
200
400
600
800
1000
1200
1400
1600
-20 -10 0 10 20 30 40 50 60 0
200
400
600
800
1000
1200
1400
1600
frequ
ency
[h]
TavgDesert
Alpes
copy Fraunhofer ISE
v
3 Modeling micro-climatic stress factors Physical modeling of module temperature for each of the different module types using David
Faimanlsquos approach (could be King Fuenteshelliphellipas well)
Macro ndash climate =gt Micro ndash climate
Irradiation wind ambient temperature =gt Tmod
Neglected IR-radiation exchange and natural convection
HT T mod amb 10 UU v
Tmod module temperature
Tamb ambient temperature
wind velocity
H solar radiation
U1 U0 a-Si 1 107 257 a-Si 3 58 258 a-Si 4 43 261
CIS 1 31 230 CIS 2 41 250 CdTe 54 234 c-Si 62 300
The parameters U are module-specific but location independent
MKoehl etal Modelling of the nominal operating cell temperature copy Fraunhofer ISE based on outdoor weathering Sol Energy Mat Sol Cells (2011)
60
3 Modeling micro-climatic stress factors
Module-temperature as time-series based on ambient climate data and as histograms (one year)
tem
pera
ture
[degC
]
Tair5000
50
module
4000
3500
300040
Freu
ency
0 20 40 60 8
a-Si 1 a-Si 2 a-Si 3 a-Si 4 CIS 1 CIS 2 CdTe c-Si
T 4500
2500
2000
1500
1000
30
20 500
0 10
222 223 224 225 time [d] Temperature in degC
copy Fraunhofer ISE
Rel
wat
er c
once
ntra
tion
[au
]
3 Modeling micro-climatic stress factors
Simulation of module humidity by FEM
Damp-heat testing 85rh 85degC J Wirth Diplomarbeit Diploma Thesis University of Freiburg 20
copy Fraunhofer ISE J P Huumllsmann et alsu bmitted to Solar Energy MaterialsampSolar Cells
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
Stress-factors at operation of PV-modules
Moisture causes hydrolysis and corrosion (Acetic acid from EVA)
Electrical potentials introduce leakage currents and reduction of cell efficiency
UV ndash irradiation causes destruction of polymeric components
Photo-degradation
Temperature cycling static oder dynamic mechanical loads lead to
Cell-breakage inter-connecture breakage delamination
Salt heat (high temperatures)
copy Fraunhofer ISE
Example for development of Accelerated Life Testingltbased on real stresses during operation of PV-moduleslt
Moisture causes hydrolysis and corrosion
Electrical potentials introduce leakage currents and reduction of cell efficiency
UV ndash irradiation causes destruction of polymeric components
Photo-degradation
Temperature cycling static oder dynamic mechanical loads lead to tensions
Cell-breakage inter-connecture breakage delamination
Salt heat (high temperatures)
copy Fraunhofer ISE
1 Monitoring climatic conditions Ambient climate and sample temperatures as 1min averaged time series
Corrosivity salt concentration as yearly or monthly dose
City or reference
Freiburg Germany
Alpine
Zugspitze
Germany
Arid
Sede Boqer
Israel
Tropical
Serpang
Indonesia (operated by TUumlV Rheinland
Maritime
Pozo Izquierdo
Gran Canaria
copy Fraunhofer ISE
Tamb
2 Monitoring micro-climatic stress factors
Module temperature monitoring during outdoor exposure
Macro ndash climate =gt Micro ndash climate
Ambient temperature Average module temperature (c-Si)
Tropics
temperature [degC] temperature [degC] -20 -10 0 10 20 30 40 50 60 70
0
200
400
600
800
1000
1200
1400
1600
-20 -10 0 10 20 30 40 50 60 0
200
400
600
800
1000
1200
1400
1600
frequ
ency
[h]
TavgDesert
Alpes
copy Fraunhofer ISE
v
3 Modeling micro-climatic stress factors Physical modeling of module temperature for each of the different module types using David
Faimanlsquos approach (could be King Fuenteshelliphellipas well)
Macro ndash climate =gt Micro ndash climate
Irradiation wind ambient temperature =gt Tmod
Neglected IR-radiation exchange and natural convection
HT T mod amb 10 UU v
Tmod module temperature
Tamb ambient temperature
wind velocity
H solar radiation
U1 U0 a-Si 1 107 257 a-Si 3 58 258 a-Si 4 43 261
CIS 1 31 230 CIS 2 41 250 CdTe 54 234 c-Si 62 300
The parameters U are module-specific but location independent
MKoehl etal Modelling of the nominal operating cell temperature copy Fraunhofer ISE based on outdoor weathering Sol Energy Mat Sol Cells (2011)
60
3 Modeling micro-climatic stress factors
Module-temperature as time-series based on ambient climate data and as histograms (one year)
tem
pera
ture
[degC
]
Tair5000
50
module
4000
3500
300040
Freu
ency
0 20 40 60 8
a-Si 1 a-Si 2 a-Si 3 a-Si 4 CIS 1 CIS 2 CdTe c-Si
T 4500
2500
2000
1500
1000
30
20 500
0 10
222 223 224 225 time [d] Temperature in degC
copy Fraunhofer ISE
Rel
wat
er c
once
ntra
tion
[au
]
3 Modeling micro-climatic stress factors
Simulation of module humidity by FEM
Damp-heat testing 85rh 85degC J Wirth Diplomarbeit Diploma Thesis University of Freiburg 20
copy Fraunhofer ISE J P Huumllsmann et alsu bmitted to Solar Energy MaterialsampSolar Cells
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
Example for development of Accelerated Life Testingltbased on real stresses during operation of PV-moduleslt
Moisture causes hydrolysis and corrosion
Electrical potentials introduce leakage currents and reduction of cell efficiency
UV ndash irradiation causes destruction of polymeric components
Photo-degradation
Temperature cycling static oder dynamic mechanical loads lead to tensions
Cell-breakage inter-connecture breakage delamination
Salt heat (high temperatures)
copy Fraunhofer ISE
1 Monitoring climatic conditions Ambient climate and sample temperatures as 1min averaged time series
Corrosivity salt concentration as yearly or monthly dose
City or reference
Freiburg Germany
Alpine
Zugspitze
Germany
Arid
Sede Boqer
Israel
Tropical
Serpang
Indonesia (operated by TUumlV Rheinland
Maritime
Pozo Izquierdo
Gran Canaria
copy Fraunhofer ISE
Tamb
2 Monitoring micro-climatic stress factors
Module temperature monitoring during outdoor exposure
Macro ndash climate =gt Micro ndash climate
Ambient temperature Average module temperature (c-Si)
Tropics
temperature [degC] temperature [degC] -20 -10 0 10 20 30 40 50 60 70
0
200
400
600
800
1000
1200
1400
1600
-20 -10 0 10 20 30 40 50 60 0
200
400
600
800
1000
1200
1400
1600
frequ
ency
[h]
TavgDesert
Alpes
copy Fraunhofer ISE
v
3 Modeling micro-climatic stress factors Physical modeling of module temperature for each of the different module types using David
Faimanlsquos approach (could be King Fuenteshelliphellipas well)
Macro ndash climate =gt Micro ndash climate
Irradiation wind ambient temperature =gt Tmod
Neglected IR-radiation exchange and natural convection
HT T mod amb 10 UU v
Tmod module temperature
Tamb ambient temperature
wind velocity
H solar radiation
U1 U0 a-Si 1 107 257 a-Si 3 58 258 a-Si 4 43 261
CIS 1 31 230 CIS 2 41 250 CdTe 54 234 c-Si 62 300
The parameters U are module-specific but location independent
MKoehl etal Modelling of the nominal operating cell temperature copy Fraunhofer ISE based on outdoor weathering Sol Energy Mat Sol Cells (2011)
60
3 Modeling micro-climatic stress factors
Module-temperature as time-series based on ambient climate data and as histograms (one year)
tem
pera
ture
[degC
]
Tair5000
50
module
4000
3500
300040
Freu
ency
0 20 40 60 8
a-Si 1 a-Si 2 a-Si 3 a-Si 4 CIS 1 CIS 2 CdTe c-Si
T 4500
2500
2000
1500
1000
30
20 500
0 10
222 223 224 225 time [d] Temperature in degC
copy Fraunhofer ISE
Rel
wat
er c
once
ntra
tion
[au
]
3 Modeling micro-climatic stress factors
Simulation of module humidity by FEM
Damp-heat testing 85rh 85degC J Wirth Diplomarbeit Diploma Thesis University of Freiburg 20
copy Fraunhofer ISE J P Huumllsmann et alsu bmitted to Solar Energy MaterialsampSolar Cells
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
1 Monitoring climatic conditions Ambient climate and sample temperatures as 1min averaged time series
Corrosivity salt concentration as yearly or monthly dose
City or reference
Freiburg Germany
Alpine
Zugspitze
Germany
Arid
Sede Boqer
Israel
Tropical
Serpang
Indonesia (operated by TUumlV Rheinland
Maritime
Pozo Izquierdo
Gran Canaria
copy Fraunhofer ISE
Tamb
2 Monitoring micro-climatic stress factors
Module temperature monitoring during outdoor exposure
Macro ndash climate =gt Micro ndash climate
Ambient temperature Average module temperature (c-Si)
Tropics
temperature [degC] temperature [degC] -20 -10 0 10 20 30 40 50 60 70
0
200
400
600
800
1000
1200
1400
1600
-20 -10 0 10 20 30 40 50 60 0
200
400
600
800
1000
1200
1400
1600
frequ
ency
[h]
TavgDesert
Alpes
copy Fraunhofer ISE
v
3 Modeling micro-climatic stress factors Physical modeling of module temperature for each of the different module types using David
Faimanlsquos approach (could be King Fuenteshelliphellipas well)
Macro ndash climate =gt Micro ndash climate
Irradiation wind ambient temperature =gt Tmod
Neglected IR-radiation exchange and natural convection
HT T mod amb 10 UU v
Tmod module temperature
Tamb ambient temperature
wind velocity
H solar radiation
U1 U0 a-Si 1 107 257 a-Si 3 58 258 a-Si 4 43 261
CIS 1 31 230 CIS 2 41 250 CdTe 54 234 c-Si 62 300
The parameters U are module-specific but location independent
MKoehl etal Modelling of the nominal operating cell temperature copy Fraunhofer ISE based on outdoor weathering Sol Energy Mat Sol Cells (2011)
60
3 Modeling micro-climatic stress factors
Module-temperature as time-series based on ambient climate data and as histograms (one year)
tem
pera
ture
[degC
]
Tair5000
50
module
4000
3500
300040
Freu
ency
0 20 40 60 8
a-Si 1 a-Si 2 a-Si 3 a-Si 4 CIS 1 CIS 2 CdTe c-Si
T 4500
2500
2000
1500
1000
30
20 500
0 10
222 223 224 225 time [d] Temperature in degC
copy Fraunhofer ISE
Rel
wat
er c
once
ntra
tion
[au
]
3 Modeling micro-climatic stress factors
Simulation of module humidity by FEM
Damp-heat testing 85rh 85degC J Wirth Diplomarbeit Diploma Thesis University of Freiburg 20
copy Fraunhofer ISE J P Huumllsmann et alsu bmitted to Solar Energy MaterialsampSolar Cells
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
Tamb
2 Monitoring micro-climatic stress factors
Module temperature monitoring during outdoor exposure
Macro ndash climate =gt Micro ndash climate
Ambient temperature Average module temperature (c-Si)
Tropics
temperature [degC] temperature [degC] -20 -10 0 10 20 30 40 50 60 70
0
200
400
600
800
1000
1200
1400
1600
-20 -10 0 10 20 30 40 50 60 0
200
400
600
800
1000
1200
1400
1600
frequ
ency
[h]
TavgDesert
Alpes
copy Fraunhofer ISE
v
3 Modeling micro-climatic stress factors Physical modeling of module temperature for each of the different module types using David
Faimanlsquos approach (could be King Fuenteshelliphellipas well)
Macro ndash climate =gt Micro ndash climate
Irradiation wind ambient temperature =gt Tmod
Neglected IR-radiation exchange and natural convection
HT T mod amb 10 UU v
Tmod module temperature
Tamb ambient temperature
wind velocity
H solar radiation
U1 U0 a-Si 1 107 257 a-Si 3 58 258 a-Si 4 43 261
CIS 1 31 230 CIS 2 41 250 CdTe 54 234 c-Si 62 300
The parameters U are module-specific but location independent
MKoehl etal Modelling of the nominal operating cell temperature copy Fraunhofer ISE based on outdoor weathering Sol Energy Mat Sol Cells (2011)
60
3 Modeling micro-climatic stress factors
Module-temperature as time-series based on ambient climate data and as histograms (one year)
tem
pera
ture
[degC
]
Tair5000
50
module
4000
3500
300040
Freu
ency
0 20 40 60 8
a-Si 1 a-Si 2 a-Si 3 a-Si 4 CIS 1 CIS 2 CdTe c-Si
T 4500
2500
2000
1500
1000
30
20 500
0 10
222 223 224 225 time [d] Temperature in degC
copy Fraunhofer ISE
Rel
wat
er c
once
ntra
tion
[au
]
3 Modeling micro-climatic stress factors
Simulation of module humidity by FEM
Damp-heat testing 85rh 85degC J Wirth Diplomarbeit Diploma Thesis University of Freiburg 20
copy Fraunhofer ISE J P Huumllsmann et alsu bmitted to Solar Energy MaterialsampSolar Cells
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
v
3 Modeling micro-climatic stress factors Physical modeling of module temperature for each of the different module types using David
Faimanlsquos approach (could be King Fuenteshelliphellipas well)
Macro ndash climate =gt Micro ndash climate
Irradiation wind ambient temperature =gt Tmod
Neglected IR-radiation exchange and natural convection
HT T mod amb 10 UU v
Tmod module temperature
Tamb ambient temperature
wind velocity
H solar radiation
U1 U0 a-Si 1 107 257 a-Si 3 58 258 a-Si 4 43 261
CIS 1 31 230 CIS 2 41 250 CdTe 54 234 c-Si 62 300
The parameters U are module-specific but location independent
MKoehl etal Modelling of the nominal operating cell temperature copy Fraunhofer ISE based on outdoor weathering Sol Energy Mat Sol Cells (2011)
60
3 Modeling micro-climatic stress factors
Module-temperature as time-series based on ambient climate data and as histograms (one year)
tem
pera
ture
[degC
]
Tair5000
50
module
4000
3500
300040
Freu
ency
0 20 40 60 8
a-Si 1 a-Si 2 a-Si 3 a-Si 4 CIS 1 CIS 2 CdTe c-Si
T 4500
2500
2000
1500
1000
30
20 500
0 10
222 223 224 225 time [d] Temperature in degC
copy Fraunhofer ISE
Rel
wat
er c
once
ntra
tion
[au
]
3 Modeling micro-climatic stress factors
Simulation of module humidity by FEM
Damp-heat testing 85rh 85degC J Wirth Diplomarbeit Diploma Thesis University of Freiburg 20
copy Fraunhofer ISE J P Huumllsmann et alsu bmitted to Solar Energy MaterialsampSolar Cells
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
60
3 Modeling micro-climatic stress factors
Module-temperature as time-series based on ambient climate data and as histograms (one year)
tem
pera
ture
[degC
]
Tair5000
50
module
4000
3500
300040
Freu
ency
0 20 40 60 8
a-Si 1 a-Si 2 a-Si 3 a-Si 4 CIS 1 CIS 2 CdTe c-Si
T 4500
2500
2000
1500
1000
30
20 500
0 10
222 223 224 225 time [d] Temperature in degC
copy Fraunhofer ISE
Rel
wat
er c
once
ntra
tion
[au
]
3 Modeling micro-climatic stress factors
Simulation of module humidity by FEM
Damp-heat testing 85rh 85degC J Wirth Diplomarbeit Diploma Thesis University of Freiburg 20
copy Fraunhofer ISE J P Huumllsmann et alsu bmitted to Solar Energy MaterialsampSolar Cells
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
Rel
wat
er c
once
ntra
tion
[au
]
3 Modeling micro-climatic stress factors
Simulation of module humidity by FEM
Damp-heat testing 85rh 85degC J Wirth Diplomarbeit Diploma Thesis University of Freiburg 20
copy Fraunhofer ISE J P Huumllsmann et alsu bmitted to Solar Energy MaterialsampSolar Cells
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
3 Modeling micro-climatic stress factors
Phenomenological modelling of moisture impact
1) Humidity at the module surface
rh (Tmod) = rh (Tamb) Psat (Tmod) Psat (Tamb)
102) Put more weight on high moisture levels
rheff =1 (1+ 100exp(-94 rh)) 08
06
04
3) Humidity level at test conditions (85rh) 02
ti = ti rheff 085 00
222 223 224 225 0
20
40
60
80
100
rH [
]
air
rH micro climate
rH
time [d]
0 02 04 06 08 1
M Koehl et al Solar Energy Materials amp Solar Cells 99 (2012) 282ndash291 copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
4 Time-transformation functions for major degradation processes
4) Process kinetics depend on module temperature (Time Transformation Function)
ttest = Lifetime (years) 6i ti(rheff Tmodi) exp [-(Ea R)(1Ttest - 1Tmodi)]
Ea = activation energy for the rate dominating degradation process
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
5 Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Testing time at 85rh85degC for 25 years lifetime
100000
100
1000
10000
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Example
Time to failure 85degC85rh
3000h
Ea gt 35 kJmol for alpine climates
Ea gt 50 kJmol for arid climates
Ea gt 60 kJmol for tropical climates
Activation energy [kJmol]Type approval test would be sufficient for Ea gt 80 kJmol
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Testing of c-Si modules from 7 different manufacturers
Nor
mal
ised
pow
er
mpp
Damp-Heat at 85degC and 85 rel humidity Damp-Heat at 90degC and 85 rel humidity
11 11
10 10
Nor
mal
ised
pow
er
mpp
09 09
08 08
07 07
06 06
05
04
05
04
03 03
02 02
01 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500
Exposure time h Exposure time h
01
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
Damp-heat testing at 85rh85degC module 1 und module 2
Exposure time hlt
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
85degC
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1
Module 2
No
rmal
ised
po
wer
m
pp
2400h 3300h
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT Damp-heat testing at 85rh85degC and 90degC module 1 und module 2
Exposure time h
-500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 03
04
05
06
07
08
09
10
11
Module 1 65 kJmol Module 2 33 kJmol
No
rmal
ised
po
wer
m
pp
2400h 3300h
a = exp [-(Ea R)(1T1 ndash 1T2)]
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
6 Evaluation of the parameters for time-transformation functions by ALT
P = G(1+ (G001-1) exp(-(t-tind (T))k(T)) ) 120120
100100 T=85degC 080080 Tind=2100h 060060 K=00082h 040040 G=026 020020
000000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
1212
11 T=90degC 0808 Tind=1500h 0606 K=00115h 0404 G=026 0202
00 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
0 100 100
0 080 080
0 060 060
0 040 040
0 020 020
0 000 0000 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000
0 1000 2000 3000 4000 5000
1200
1000
0800
0600
0400
0200
0000 0 1000 2000 3000 4000 5000
etime (85degC) [h] 2412 2576 2821 3047 3160 3227 3548 ivation energy [kJmol] 70 73 30 68 26 55 53
mate class A A C A C B B
Qualification for different stress levels or climate zones allows diversification of PV-modules
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
Displacement on cell (cm)
Inte
nsity
(arb
uni
ts)
Degradation of the modules
Polymer Analysis by Raman-Spectroscopie
Comparison of the Vinyl-Band (red) and the fluorescence-background (black) unaged and after 4000h damp-heat-testing
Elektroluminescence-picture 70 14 of the degraded cells 65
60 12
55
50 10
45 08
40
35 06
30
25 04
20
15 02
10
5 00
0 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Location above the cell [cm]
Average Ref_I(1660) Average 4000h dh_I(1660)
Average Ref_I(2863)I(2913) Average 4000h dh_I(2863)I(2913)
Inte
nsi
ty [
arb
un
its]
C Peike etal Non-destructive degradation analysis of encapsulants in PV modules copy Fraunhofer ISE by Raman Spectroscopy Sol En Mat Sol Cells (2011)
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
6 Evaluation of the service life time for different climates
Testing time at 85rh85degC for 25 years lifetime 100000
Climate classes
A Most severe moisture stress
B Moderate moisture stress
C Low moisture stress
test
ing
time
85
degC [h
]
tropical arid alpine
20 40 60 80 100 120
Activation energy [kJmol]
10000
1000
100
Assumptions
The measured stress levels are representative
The model for the kinetics is valid
The constant load DH test reflects reality
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
4
100
1000
10000
Test
ing
time
8
5 C
[h]
tropical arid alpine
Nor
mal
ised
pow
er
mpp
7 Modeling expected degradation for validation by outdoor exposure
Power reduction after 3 years outdoor exposure lt 3
Exposure time has to be doubled
Equivalent to 3 years operation 11
10
09
08
07
06
05
04
03
02
01 0 20 40 60 80 100 -500 0 500 1000 1500 2000 2500 3000 3500 4000 C B A
Activation energy [kJmol] Exposure time h
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
-66
7 Degradation effects during outdoor exposure
Changes of the electrical performance at the outdoor exposure site
Test site Tropical Arid Urban Alpine Average
Module 1 -15 -06 -09 -11 -10 2 -01 -11 -08 -47 -17 3 -10 -01 -05 13 -01 4 -32 -01 17 -21 5 -01 -22 -18 -08 -12
Average -12 -08 -05 -24 -12
After 3 years operation hardly out of the error bars
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
After 3 years on the alpes
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Degradation of module materials - UV-induced fluorescencelt2 a alpine outdoor exposure 2 a desert outdoor exposure
Combination of electroluminescence and fluorescence
J Schlothauer et al Fluorescence imaging a powerful tool for the investigation of polymer copy Fraunhofer ISE
degradation in PV modules Photovoltaics International journal November 2010
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
Browning and photo-bleaching - UV-induced fluorescencelt
Combination of electroluminescence and fluorescenc
2 a desert outdoor exposure
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
7 Degradation effects during outdoor exposure
a) Tropical
b) Arid
c) Moderate
d) Alpine
Effect of outdoor weathering on fluorescence spectra
UV
-rad
iatio
n
Moi
stur
e le
vel
Module types
J Schlothauer et al Degradation of the encapsulant polymer in outdoor weathered photovoltaic copy Fraunhofer ISE modules Spatially resolved inspection Solar Energy MaterialsampSolar Cells 102 (2012) 75ndash85
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Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
1
2
3
5
4
7
6
Methodology for design of Accelerated Service Life Testing
Monitoring climatic conditions
Monitoring micro-climatic stress factors
Modeling micro-climatic stress factors
Time-transformation functions for major degradation processes
Modeling corresponding ALT ndash conditions for micro-climatic stress factors
Evaluation of sample-dependent parameters for time-transformation functions
Modeling of expected degradation for outdoor exposure and validation of the tests
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
Conclusions
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
Conclusions and outlook
Accelerated Damp-heat service life tests have been proposed
bull Based on monitored climatic data
bull Modelled micro-climatic stress conditions
bull Modelled kinetic of the degradation processes
but final validation was not achieved yet
Tests for other stress factors (UV temperature cycling potential induced degradation etc) and their combinations are under development
Global stress mapping will allow qualification of diversified specialised products for different climatic zones
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE
Thank you for your Attentionlt
Fraunhofer Institute for Solar Energy Systems ISE
Michael Koumlhl
wwwisefraunhoferde
michaelkoehlisefraunhoferde
copy Fraunhofer ISE