Spectral analysis of various thin film modules using high precision spectral response data and solar spectral irradiance data

1. ®TÜV,TUEVandTUVareregisteredtrademarks.Utilizationandapplicationrequirespriorapproval.
∫ ⋅⋅=≈
b
a
iSCPhoto dSREAII λλλ )()(
80%
90%
100%
110%
120%
1,55 1,57 1,59 1,61 1,63 1,65 1,67 1,69 1,71 1,73 1,75
∆Isc[%]
APE [eV]
µ-Si
This poster contains results of high-precision indoor and outdoor measurements of different PV module technologies performed at the headquarters of TÜV
Rheinland, Cologne. Modules based on CdTe, CI(G)S, a-Si, a-Si/µ-Si, a-Si/a-Si and c-Si (mono and poly) semiconductors were analyzed nondestructively
according to their spectral response and technology specific differences are pointed out. After the indoor characterization the modules were exposed outdoor
for one year, steadily measuring the maximum power point PMPP and the I/V-curves with the corresponding solar spectrum. With this data volume it is
possible to describe the spectral conditions at the test-site in Cologne using the APE-Method. In a next step the influence on the module performance and the
energy yield of the different technologies are analyzed. The photo current is calculated theoretically by the integral of spectral response data and spectral
measurements and compared to temperature and irradiance corrected real outdoor measurements.
Depending on the position of the sun related to the module and the
atmosphere the spectral distribution of solar irradiation can be shifted into
blue or red wavelength areas. Some technologies can benefit while others
may be disadvantaged depending on their spectral response. In what way
and why these spectral shifts happen in the course of a day and the
season and what influence they have on the energy yield of a certain
technology are described in the following.
Markus Schweiger, Ulrike Jahn, Werner Herrmann
TÜV Rheinland Energie und Umwelt GmbH, Am Grauen Stein, 51105 Cologne, Germany
Tel.: +49 221 806-5585, E-Mail: Markus.Schweiger@de.tuv.com
RESULTS
CONCLUSIONS
SPECTRAL ANALYSIS OF VARIOUS THIN FILM MODULES USING HIGH
PRECISION SPECTRAL RESPONSE DATA AND
SOLAR SPECTRAL IRRADIANCE DATA
Figure 1 Non-destructive measurement of the spectral response (SR) of a triple-junction module with the test equipment at
TÜV Rheinland, Cologne
Spectral response of different PV module technologies
Characterizing solar spectrum with the average photon energy (APE)
Influence of spectrum on performance and yield
Since 2013 TÜV Rheinland runs extensive energy yield
measurements at five different locations all over the world.
Requests can be sent to the authors.
Significant differences in SR-Signal of CIGS and a-Si specimens
APE-Method appropriate method to describe solar spectrum
Automatable procedure to correct T, G and MM implemented
Sinus-shaped performance fluctuation of a-Si because of spectrum
Spectrum not significant for energy yield of c-Si and most CIGS
Annual gains of +3% (some a-Si) and +1% (CdTe) calculated in 11/12
INTRODUCTION
0,00
0,20
0,40
0,60
0,80
1,00
1,20
300 500 700 900 1100 1300
Rel.SpectralResponse.
Wavelength [nm]
Norm AM1.5 a-Si CIS CdTe CIGS poly c-Si mono c-Si CIGS
0,00
0,20
0,40
0,60
0,80
1,00
1,20
300 500 700 900 1100 1300
Rel.SpectralResponse
Wavelength [nm]
CI(G)S
0,00
0,20
0,40
0,60
0,80
1,00
1,20
300 400 500 600 700 800 900 1000
Rel.SpectralResponse
Wavelength [nm]
Top-Layer Bottom-Layer
The SR-equipment is suitable
for all common module
designs (Fig. 1)
Step-size 1nm for single-,
double- and triple-junction
specimens possible
Large spread of the spectral
response for different module
technologies (Fig. 2)
Also large technology internal
spreads for a-Si and CIGS
(Fig. 3 + 4)
The spectral mismatch (MM)
and the theoretical photo
current can be calculated to
improve PMax determination
and outdoor monitoring
80%
90%
100%
110%
120%
∆Isc[%]
CdTe
80%
90%
100%
110%
120%
∆Isc[%]
CI(G)S & c-Si
80%
90%
100%
110%
120%
∆Isc[%]
a-Si
80%
90%
100%
110%
120%
∆Isc[%]
CdTe
80%
90%
100%
110%
120%
∆Isc[%]
CI(G)S & c-Si
80%
90%
100%
110%
120%
1,55 1,57 1,59 1,61 1,63 1,65 1,67 1,69 1,71 1,73 1,75
∆Isc[%]
APE [eV]
a-Si/µ-Si
80%
90%
100%
110%
120%
∆Isc[%]
a-Si
Spectrum < 1.65 eV red
Spectrum > 1.65 eV blue
Spectrum = 1.65 eV STC
Winter red spectrum (Fig. 5 + 8)
Calculated Measured
1,3
1,4
1,5
1,6
1,7
1,8
1,9
2
2,1
6:00 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00
APE[eV]
time
AM1,5g Summer (21.08.2010) Fall (10.10.2010) Winter (29.01.2011) Spring (19.04.2011)
2
2,2
2,4
2,6
2,8
3
3,2
3,4
3,6
3,8
4
4,2
4,4
4,6
4,8
5
5,2
5,4
Isc[A]
Isc: T,G corrected Isc: T,G,MM corrected
)(
)(
)(
λλ
λ
λ
Pq
I
q
hcSR
QE
Φ⋅
=⋅=
Figure 5 Solar spectral irradiance drift for cloudless days in
summer (blue), spring (green), fall (yellow) and winter (red)
for modules mounted facing south and 35° tilted in Cologne
Figure 9 Correcting spectral effects of an a-Si specimenFigure 8 Seasonal variations of APE-values and average
APE-value per month
Figure 6 Dependency of ISC on spectral changes,
calculated with formula, normalized to ISC,STC at 1.65 eV
Figure 7 Dependency of ISC on spectral changes, measured
(T, G corrected), normalized to ISC,STC at 1.65 eV
∫
∫
Φ⋅
= b
a
ie
b
a
i
dq
dE
APE
λλ
λλ
)(
)(
Figure 2 Rel. spectral response signal of different PV-
module technologies in comparison with IEC 60904-3
spectrum
Figure 3 + 4 Rel. spectral response signal of different CIGS
and a-Si modules, illustrating significant differences within
the same thin-film technology
Results of calculated and measured ISC (APE) almost similar (Fig. 6+7)
Dependency of a-Si/µ-Si on spectrum screened out as combination of
a-Si behavior for APE < 1.65eV and µ-Si behavior for APE > 1.65eV
significant losses because of current mismatch expected
Almost no dependency of c-Si and most CIGS on spectrum
Strong dependency of a-Si and small dependency of CdTe on spectrum
The seasonal average spectrum was calculated to 1.68 eV in 2011/12.
Small energy yield gains of max. +3% (some a-Si) and +1% (CdTe).