7th PVPMC Energy Rating and Module Performance Modeling Workshop, 30-31 March, 2017 in Lugano, Switzerland

1. Thomas Fey 30.03.2017
Sensitivity analysis for energy rating:
Linearity, T-coefficient and AOI dependence
of a reference solar cell
National Metrology Institute
a

2. Standard Test Conditions (STC):
Solar cell temperature, T = 25 °C•
-2
Irradiance, E = 1000 W m•
Reference solar spectrum AM 1.5•
(IEC 60904-3)
Laboratory
Motivation
Thomas Fey 1
Bruce W Forgan,
WMO RAV Metrology Workshop
Melbourne, November 2011
Australian Goverment
Bureau of Meteorology

3. Standard Test Conditions (STC):
Solar cell temperature, T = 25 °C•
-2
Irradiance, E = 1000 W m•
Reference solar spectrum AM 1.5•
(IEC 60904-3)
Laboratory
Motivation
Reality:
Temperatures up to 75 °C•
-2
Irradiance less than 1000 W m•
AMx, direct + diffuse•
IEC 61853
Application
Thomas Fey 2
Bruce W Forgan,
WMO RAV Metrology Workshop
Melbourne, November 2011
Australian Goverment
Bureau of Meteorology

4. State of the Art
Thomas Fey 3
400 600 800 1000 1200
0
0.5
1.0
1.5
λ / nm
-2-1
E/Wmnm
AM1.5 spectra
-1
s/mAWm²
λ / nm
400 600 800 1000 1200
Spectral responsivity
Spectral and integral measurement methods
I = ∫ · ds(λ) E(λ) λ

5. Further parameters
Thomas Fey 4
400 600 800 1000 1200
0
0.5
1.0
1.5
λ / nm
-2-1
E/Wmnm
AM1.5 spectra
-1
s/mAWm²
λ / nm
400 600 800 1000 1200
Spectral responsivity
I = ∫ · ds(λ) E(λ) λ
Spectral responsivity(λ):
1. Linearity
2. Temperature
3. AOI dependence
Irradiance/Radiance (λ):
1. AMx
2. Direct, diffuse and albedo

6. New approach
Thomas Fey 5
400 600 800 1000 1200
0
0.5
1.0
1.5
λ / nm
-2-1
E/Wmnm
AM1.5 spectra
-1
s/mAWm²
λ / nm
400 600 800 1000 1200
Spectral responsivity
= λ λ λ λ λλ λ λ λI ∫ ∫ ( , , , ) · ( ( , ) + ( , ) + ( , )) d dSC , direct , diffuse , albedoΩ Ω Ω Ω ΩΩ s E L L LT
Spectral responsivity(λ):
1. Linearity
2. Temperature
3. AOI dependence
Irradiance/Radiance (λ):
1. AMx
2. Direct, diffuse and albedo

7. 1200400 600 800 1000
-12
s/mAWm
Differential spectral responsivity
λ /nm
DSR-method
Thomas Fey 6
Metzdorf, J.: Calibration of solar cells.
The differential spectral responsivity method.
Applied Optics, 26:1701–8, 1987.
: Eb= 0 W/m²
: Eb=
-2
10 W m
: Eb=
-2
25 W m
: Eb=
-2
105 W m
: Eb=
-2
205 W m
: Eb=
-2
920 W m
: Eb=
-2
1130 W m

8. Spectral responsivity and Linearity
Thomas Fey 7
1200400 600 800 1000
-12
s/mAWm
Differential spectral responsivity
λ /nm
-2
E / W mb
100101 1000
Linearity
-1.5
0
-0.5
-1.0
(s-ssSTCSTC)//%
-2.0
1200400 600 800 1000
-12
s/mAWm
Spectral responsivity
λ /nm

9. : Pyranometer
: c-Si reference s. c.
Spectral mismatch correction
Thomas Fey 8
400 600 800 1000
-12
s/mAWm
Spectral responsivity
λ /nm
400 600 800 1000
λ / nm
Spectra
REF - Reference solar cell
DUT - Device under test
STC - Standard test conditions
M =
= 1.00006
DUT
∫E ( )·s (λ)dλAM1.5 λ REF
∫E (λ)·s (λ)dλmeas.
DUT
∫E (λ)·s (λ)dλmeas.
REF
∫E (λ)·s (λ)dλAM1.5
I = · ·I
DUT
STC
REF
STC
REF
meas.
DUT
meas.
I
IM
1
IEC 60904-7
with “bandpass filters“
300 nm < λ < 1200 nm
WRONG!
0
0.5
1.0
1.5
-2-1
E/Wmnm
≙ 0.006 %
: AM1.5G
: Measured AM 1.5

10. Spectral mismatch correction
Thomas Fey 9
REF - Reference solar cell
DUT - Device under test
STC - Standard test conditions
M =
= 0.986
DUT
∫E ( )·s (λ)dλAM1.5 λ REF
∫E (λ)·s (λ)dλmeas.
DUT
∫E (λ)·s (λ)dλmeas.
REF
∫E (λ)·s (λ)dλAM1.5
I = · ·I
DUT
STC
REF
STC
REF
meas.
DUT
meas.
I
IM
1
full spectral range
20001000
-12
s/mAWm
Spectral responsivity
λ /nm
1000 2000 3000
0.5
1.0
1.5
λ / nm
-2-1
E/Wmnm
Spectra
: AM1.5G
: Measured AM 1.5
IEC 60904-7
: Pyranometer
: c-Si reference s. c.
≙ 1.4 %
3000

11. T-coefficient
Thomas Fey 10
1200400 600 800 1000
-12
s/mAWm
Differential spectral responsivity
λ /nm
: T = 20°C
: T = 25°C
: T = 30°C
1200400 600 800 1000
-1
T/%KC
T-coefficient
λ /nm
: T-coefficient
: s
: EAM1.5
: weight. T-coef.
AM1.5 weigthed T-coefficient : 900 ± 100 ppm/K

12. Linearity + T-coefficient
Thomas Fey
-2
E / W mb
100101 1000
Linearity
-1.5
0
-0.5
-1.0
(s-ssSTCSTC)//%
-2.0
Irradiance Temperature
-2
W m 15 °C 25 °C 50 °C 75 °C
1100 (-0.8) 0.1 2.3 4.6
1000 -0.9 0 2.2 4.5
800 -1.1 -0.2 2.0 4.3
600 -1.3 -0.4 1.8 4.1
400 -1.5 -0.6 1.6 (3.9)
200 -1.9 -1.0 (1.2) (3.5)
100 -2.1 -1.2 (1.0) (3.3)
1200400 600 800 1000
-1
T/%KC
T-coefficient
λ /nm
Relative change of
short circuit
current, ΔI / %SC
11
IEC 61853-1
: T-coefficient
: s
: EAM1.5
: weight. T-coef.

13. Efficiency
Thomas Fey 12
-2
E / W mb
1005010 1000
Open circuit voltage
-20
0
-10
ΔU/U/%OCOC,STC
-30
Irradiance Temperature
-2
W m 15 °C 25 °C 50 °C 75 °C
1100 (2.8) 0 -8 -16
1000 3 0 -8 -16
800 3 0 -8 -16
600 2 -1 -9 -18.5
400 0.6 -2.5 -10.5 (-19.5)
200 -2.7 -5.5 (-14) (-22.5)
100 -5.5 -8.5 (-17) (-25.5)
Fill factor
Relative change of
efficiency, Δη / %
500
0
-5
-10
-2
E / W mb
1005010 1000500
ΔFF/FF/%STC
T / °C
20
30
40
50
60
T / °C
20
30
40
50
60
IEC 61853-1

14. Thomas Fey 13
φ, θ - Goniometer
φ
θ
Reference
solar cell
φ, θ - Goniometer
A
300 nm < λ < 1200 nm

15. Thomas Fey
Spectral angular response
0 20 60 80
θ / °
40
Deviationfromcosine/%
0
-5
-15
-20
-10
0 20 60 80
θ / °
40
Deviationfromcosine/%
0
-5
-15
-20
-10
5
-25
-30
AM1.5 + s weighted spectral angular responseSpectral angular response
λ / nm
400
600
800
1000
-25
-30
14

16. Thomas Fey 15
Summary
Calculation of I (/P ):SC max
Consideration of , ,linearity temperature AOI dependence
and spectral distribution
• : 1.4 % at “AM1.5“ conditionsSpectral mismatch
-2 -2
Energy rating matrix (15°C < < 75 °C, 100 Wm < < 1100 Wm )T E
• Isc: -2.1 % to 4.6%
• η: -18.5 % to 3 %
Spectral and integral shownAOI dependence
= λ λ λ λ λλ λ λ λI ∫ ∫ ( , , , ) · ( ( , ) + ( , ) + ( , )) d dSC , direct , diffuse , albedoΩ Ω Ω Ω ΩΩ s E L L LT

17. UV+VIS spectrometer
Wavelength range: 220 - 1020 nm
Bandwidth : 3.7 nm
Sampling interval : 0.8 nm
Infrared spectrometer
Wavelength range: 780 - 1650 nm
Bandwidth: 9 nm
Sampling interval: 2.1 nm
Extended IR spectrometer
Wavelength range: 1500 - 2150 nm
Bandwidth: 15 nm
Sampling interval: 4 nm
Entrance optics
Field of View: 5° FWHM
Stray light reduced design
Digital camera
Field of View: 120°
For quality control and documentation purposes
Dual axis tracking unit
Range zenith: -42.5° - 105°
Range azimuth:
Recent activities:Outdoor measurements
Thomas Fey 16
Solar cells
-10° - 370°

18. λ = 400 nm
λ = 1000 nm
...clear sky (exemplary)
λ = 1000 nm
λ = 400 nm
Diffuse radiance...
...cloudy sky (exemplary)
Thomas Fey 17
Recent activities:Diffuse spectral distribution

19. Thomas Fey 18
Recent activities:Diffuse spectral distribution
-2-1-1
L/Wmsrnm
1200400 600 800 1000
λ / nm
0°
10°
20°
30°
40°
50°
60°
70°
80°90°100°
110°
120°
130°
140°
150°
160°
170°
180°
190°
200°
210°
220°
230°
240°
250°
260° 270° 280°
290°
300°
310°
320°
330°
340°
350°

20. Recent activities:Spectral angular correction
Thomas Fey 19
0 20 60 80
ϑ / °
40
Deviationfromcosine/%
0
-5
-15
-20
-10
5
-25
-30
Spectral angular response
λ / nm
400
600
800
1000
λ = 1000 nm
will be published soon