This document discusses outdoor module characterization methods used to generate power matrices and correct for angle of incidence and spectral mismatch effects. It presents three outdoor methods for generating power matrices: 1) an automated two-axis tracker method used by TUV Rheinland PTL, 2) a manual two-axis tracker with mesh screens method also used by TUV, and 3) a method using fixed tilt modules or grid-tied arrays. It also examines the effects of angle of incidence on clean and soiled modules, and how to calculate and minimize spectral mismatch error for outdoor characterization methods.
Semelhante a 2014 PV Performance Modeling Workshop: Outdoor Module Characterization Methods: Power Matrix, Angle of Incidence and Spectral Mismatch Correction:
2014 PV Performance Modeling Workshop: Outdoor Module Characterization Methods: Power Matrix, Angle of Incidence and Spectral Mismatch Correction:
1. 1
Outdoor Module Characterization Methods:
Power Matrix, Angle of Incidence and
Spectral Mismatch Correction
Mani G. TamizhMani
TUV Rheinland PTL
Arizona State University PRL
Presented at the 2014 Sandia PV Performance Modeling Workshop, Santa Clara, CA. May 5, 2014
Published by Sandia National Laboratories with the Permission of the Author.
gtamizhmani@us.tuv.com
2. Motivation
Qualification PLUS
A New ANSI/TUV-R Standard
• As the PV Industry matures, PV Reliability is
becoming more important
o Project developers want to make bankable investments
• PV customers are asking for tests that “go
beyond” the standard qualification test (IEC
61215).
Note:
“Qualification PLUS” testing is expected to be adopted by the California Energy Commission
in the near future.
3. TÜV Rheinland PTL, a Standards Developing Organization (SDO) for the
American National Standards Institute (ANSI), has now initiated the development
of two new American National Standards:
• ANSI / TUV-R 71732-01:201X: Qualification PLUS (Q+) Testing for PV
Modules - Test and Sampling Requirements
• ANSI / TUV-R 71733-01:201X: Quality Management System (QMS)
Requirements for PV Manufacturing
TUV Rheinland is now seeking industry participation in the respective
standards’ working groups. Stakeholders include manufacturers of PV Modules,
Project Investors and Developers, Utility Companies, PV Consumers, Incentive
Programs as well as Engineering and Insurance Companies. To get involved,
please click here.
http://education.tuv.com/join-ansi-working-groups/
Seeking Members for the ANSI Working Group (WG)
4. 4
Outline
Pmax matrix generation standards
Outdoor methods to generate Pmax matrix
M e t h o d 1 : S a n d i a m e t h o d b a s e d o n a n a u t o m a t e d 2 - a x i s
t r a c k e r ( u s e d a t T U V R h e i n l a n d P T L )
M e t h o d 2 : M e s h s c r e e n m e t h o d b a s e d o n a m a n u a l 2 - a x i s
t r a c k e r ( u s e d a t T U V R h e i n l a n d P T L )
M e t h o d 3 : M P P T m e t h o d b a s e d o n a f i x e d t i l t a r r a y m e t h o d
Angle of incidence effect
C l e a n a n d s o i l e d m o d u l e s u s i n g o u t d o o r m e t h o d
Spectral mismatch error
S p e c t r a l m i s m a t c h e r r o r c a l c u l a t i o n f o r o u t d o o r m e t h o d
Conclusions
5. 5
Pmax Matrix Generation Standards:
UL 4730 and IEC 61853
Key to improve accuracy:
• Avoid/minimize extrapolation
• Avoid/minimize long range translation
6. UL 4730: 5 Test Conditions
www.solarABCs.org
UL 4730 standard is based on the
following Solar ABCs report
12. 12
Manual 2-Axis Tracking
(Cool the module; Take I-V as it warms up)
Mesh screens to change irradiance
Pmax Matrix Generation:
Mesh screen method – Manual 2-axis tracker based
Karen Paghasian et al., IEEE PVSC 2011
Two reference cells
13. 13
1, 2 & 3 = IEC 60891 procedures; 4 = NREL procedure
Pmax Matrix Generation:
Using IEC 60891 models and results (example)
Efficiency does not remain the same!
Short range translation for accurate matrix generation is required!
15. Outdoor Method 4: Matrix Generation Using Fixed Tilt Modules (or
Grid Tied Arrays)
15
• Monitor (6 minutes): MPPT, POA irradiance and Module temperature
• If one module used: Many days of monitoring required
• If two or more identical modules used: Only few days of monitoring required
• A combination of back-insulated, mesh screen-filtered modules can also be
used to reduce the number of monitoring days
Source: K. Koka et al., IEEE Photovoltaic Specialists Conference, June 2011
18. AOI Effect on Cleaned Modules:
Practically no AOI difference between technologies
as the interface (air/glass) is the same for all
19. Soiling level: A – Heavy, B – Medium-Heavy, C – Medium, D –Light, E – Cleaned
Sample Name (Soiling Level) Critical Angle (3% and above loss)
Sample E (Cleaned) 57o
Sample D (Light; 1.7 g/m2
) 42o
Sample C (Medium; 2.7 g/m2
) 38o
Sample B (Medium Heavy; 4.9 g/m2
) 37o
Sample A (Heavy; 11.8 g/m2
) 20o
Source: J.J. Joseph et al. SPIE,
San Diego, August 2014 (accepted)
AOI Effect on Soiled Modules:
AOI loss increases as the soiling density increases
21. 21
Source: Sandia
Reference spectrum ~ Outdoor Test Spectrum
Test spectra (AMa=2.46 and Ama=4.70) are ONLY SLIGHTLY DIFFERENT from the reference spectrum (Ama=1.5)
22. Reference spectrum # Test Spectrum
Test spectrum is VERY DIFFERENT from the reference spectrum
Red line = Reference spectrum
Black line = Xe-arc lamp spectrum
If matched reference technology is NOT used to measure the irradiance level, the performance
measurement error (spectral mismatch error) will be very HIGH (see later).
24. 24
where:
M = spectral mismatch parameter;
E(λ) = spectral irradiance (Wm-2/nm);
E0(λ) = reference spectral irradiance (Wm-2/nm);
Rr(λ) = spectral response of reference cell (A/W);
Rt(λ) = spectral response of photovoltaic device (A/W).
Spectral mismatch factor (M) = Current correction factor
M=
E λ R λ dλ
b
a
E λ Rr λ dλ
d
c
×
E0 λ Rr λ dλ
d
c
E0 λ Rt λ dλ
b
a
M = 1 if the reference device is matched with the test device
M = 1 if test spectrum is matched with the reference spectrum
25. Spectral Response Depends on the Technology
If the reference cell technology (e.g. c-Si) is not matched with the test technology (e.g. CdTe),
then it is imperative either to experimentally match the test spectrum or to mathematically correct
for the spectral mismatch error.
26. 26
Source: Newport Corporation, Application Note 51
Spectral Mismatch Factor for Simulated Light (Xe-arc lamp)
If the reference cell technology (e.g. c-Si) is not matched with the test
technology (e.g. CdTe), the spectral mismatch error can NOT be ignored.
27. 27
0.940
0.960
0.980
1.000
1.020
1.040
1.060
7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00
SpectralMismatchFactor
Time (hh:mm )
Spectral Mismatch Factor for May 25, '09
A191 (Mono-Si) is the reference device
A191 (Mono-Si)
A209 (CdTe)
A187 (Mono-Si)
A203 (Poly-Si)
A210 (GaAs)
-5% Limit
+5% Limit
Spectral Mismatch Factor for Natural Sunlight (Daily)
Even if the reference cell technology (e.g. c-Si) is not matched with the test
technology (e.g. CdTe), the spectral mismatch error will be very small because
the test spectrum is practically matched with the reference spectrum!
28. • Pmax Matrix Generation
Three outdoor methods presented
First two methods are used by TUV Rheinland PTL
• Angle of Incidence Effect
Practically identical for all technologies if clean-glass
superstrate is used
AOI loss increases as the soiling density increases
• Spectral Mismatch Error
Negligibly small if natural sunlight is used with the
matched reference cell technology
Conclusions
29. Thanks for your attention!
Mani G. TamizhMani
gtamizhmani@us.tuv.com