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

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 WorkshopMelbourne, November 2011Australian GovermentBureau of Meteorology

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 WorkshopMelbourne, November 2011Australian GovermentBureau of Meteorology

State of the Art

Thomas Fey 3

400 600 800 1000 12000

0.5

1.0

1.5

λ / nm

-2-1

E / W

m n

m

AM1.5 spectra

-1

s / m

A W

m²

λ / nm400 600 800 1000 1200

Spectral responsivity

Spectral and integral measurement methods

I = ∫ · ds(λ) E(λ) λ

Further parameters

Thomas Fey 4

400 600 800 1000 12000

0.5

1.0

1.5

λ / nm

-2-1

E / W

m n

m

AM1.5 spectra

-1

s / m

A W

m²

λ / nm400 600 800 1000 1200

Spectral responsivity

I = ∫ · ds(λ) E(λ) λ

Spectral responsivity(λ):1. Linearity2. Temperature3. AOI dependence

Irradiance/Radiance (λ):1. AMx2. Direct, diffuse and albedo

New approach

Thomas Fey 5

400 600 800 1000 12000

0.5

1.0

1.5

λ / nm

-2-1

E / W

m n

m

AM1.5 spectra

-1

s / m

A W

m²

λ / nm400 600 800 1000 1200

Spectral responsivity

= λ λ λ λ λλ λ λ λI ∫ ∫ ( , , , ) · ( ( , ) + ( , ) + ( , )) d d SC , direct , diffuse , albedoΩ Ω Ω Ω ΩΩ s E L L LT

Spectral responsivity(λ):1. Linearity2. Temperature3. AOI dependence

Irradiance/Radiance (λ):1. AMx2. Direct, diffuse and albedo

1200400 600 800 1000

-12

s / m

A W

m

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

=

-210 W m

:

Eb

=

-225 W m :

Eb

=

-2105 W m

: Eb = -2

205 W m

: Eb

= -2920 W m

:

Eb

=

-21130 W m

Spectral responsivity and Linearity

Thomas Fey 7

1200400 600 800 1000

-12

s / m

A W

m

Differential spectral responsivity

λ /nm

-2E / W mb

100101 1000

Linearity

-1.5

0

-0.5

-1.0(s

-s s

ST

CS

TC

) /

/ %

-2.0

1200400 600 800 1000

-12

s / m

A W

m

Spectral responsivity

λ /nm

: Pyranometer

: c-Si reference s. c.

Spectral mismatch correction

Thomas Fey 8

400 600 800 1000

-12

s / m

A W

m

Spectral responsivity

λ /nm400 600 800 1000

λ / nm

Spectra

REF - Reference solar cellDUT - Device under testSTC - 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 = · ·IDUT

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 / W

m n

m

≙ 0.006 %

: AM1.5G

: Measured AM 1.5

Spectral mismatch correction

Thomas Fey 9

REF - Reference solar cellDUT - Device under testSTC - 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 = · ·IDUT

STC

REF

STC

REF

meas.

DUT

meas.

I

IM

1

full spectral range

20001000

-12

s / m

A W

m

Spectral responsivity

λ /nm1000 2000 3000

0.5

1.0

1.5

λ / nm

-2-1

E / W

m n

m

Spectra

: AM1.5G

: Measured AM 1.5

IEC 60904-7

: Pyranometer

: c-Si reference s. c.

≙ 1.4 %

3000

T-coefficient

Thomas Fey 10

1200400 600 800 1000

-12

s / m

A W

m

Differential spectral responsivity

λ /nm

: T = 20°C

: T = 25°C

: T = 30°C

1200400 600 800 1000

-1T

/ %

KC

T-coefficient

λ /nm

: T-coefficient

: s

: EAM1.5

: weight. T-coef.

AM1.5 weigthed T-coefficient : 900 ± 100 ppm/K

Linearity + T-coefficient

Thomas Fey

-2E / W mb

100101 1000

Linearity

-1.5

0

-0.5

-1.0

(s-s

sS

TC

ST

C)

/ / %

-2.0

Irradiance Temperature-2W 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

-1T

/ %

KC

T-coefficient

λ /nm

Relative change ofshort circuit current, ΔI / %SC

11

IEC 61853-1

: T-coefficient

: s

: EAM1.5

: weight. T-coef.

Efficiency

Thomas Fey 12

-2E / W mb

1005010 1000

Open circuit voltage

-20

0

-10

ΔU

/U / %

OC

OC

,ST

C

-30

Irradiance Temperature-2W 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 ofefficiency, Δη / %

500

0

-5

-10

-2E / W mb

1005010 1000500

ΔF

F /

FF

/ %

ST

C

T / °C

20

30

40

50

60

T / °C

20

30

40

50

60

IEC 61853-1

Thomas Fey 13

φ, θ - Goniometer

φ

θ

Reference solar cell

φ, θ - GoniometerA

300 nm < λ < 1200 nm

Thomas Fey

Spectral angular response

0 20 60 80θ / °40

Dev

iati

on f

rom

cos

ine

/ % 0

-5

-15

-20

-10

0 20 60 80θ / °40

Dev

iati

on f

rom

cos

ine

/ %

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

Thomas Fey 15

Summary

Calculation of I (/P ): SC max

Consideration of , , linearity temperature AOI dependenceand spectral distribution

• : 1.4 % at “AM1.5“ conditionsSpectral mismatch

-2 -2Energy 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 d SC , direct , diffuse , albedoΩ Ω Ω Ω ΩΩ s E L L LT

UV+VIS spectrometer Wavelength range: 220 - 1020 nmBandwidth : 3.7 nmSampling interval : 0.8 nm

Infrared spectrometer Wavelength range: 780 - 1650 nmBandwidth: 9 nmSampling interval: 2.1 nm

Extended IR spectrometerWavelength range: 1500 - 2150 nmBandwidth: 15 nmSampling interval: 4 nm

Entrance opticsField of View: 5° FWHMStray light reduced design

Digital cameraField of View: 120°For quality control and documentation purposes

Dual axis tracking unitRange zenith: -42.5° - 105°Range azimuth:

Recent activities:Outdoor measurements

Thomas Fey 16

Solar cells

-10° - 370°

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

Thomas Fey 18

Recent activities:Diffuse spectral distribution

-2-1

-1L

/ W

m sr

n

m

1200400 600 800 1000λ / 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°

Recent activities:Spectral angular correction

Thomas Fey 19

0 20 60 80ϑ / °40

Dev

iati

on f

rom

cos

ine

/ %

0

-5

-15

-20

-10

5

-25

-30

Spectral angular response

λ / nm

400

600

800

1000

λ = 1000 nm

will be published soon