Download - 5 - PV Classes - Characterization
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CHARACTERIZATIONCHARACTERIZATIONSolarSolar cellscells andand modulesmodules
CharacterizationCharacterizationSolar cell/modules characterization
Spectral responseIV curve
Other relevant testsDegradationReflectanceLifetime
Infrared mapping (luminescence)
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Spectral response
CharacterizationCharacterizationSolar cell/modules characterization
Spectral response (SR) is the short circuit current producedy e ce w en um na e y a g ven power
External quantum efficiency (EQE) is the probability of aincident photon contributing to one electron to the short circuitcurrentInternal quantum efficiency (IQE) is the probability of aabsorbed photon contributing to one electron to the shortcircuit current
opt
sc
P I
SR EQE hcq
SR
R
EQE IQE
1
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Spectral response
H. Mackel, Capturing the spectra of solar cells, PhD Thesis, Australian National University, 2004
CharacterizationCharacterizationSolar cell/modules characterization
Spectral response
E Q E
1
Back recombination
Reflectivity
=hc/E g
Front recombination
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Spectral response
Determination of diffusion length:
if -1
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IV curve
CharacterizationCharacterizationSolar cell/modules characterization
IV curve
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IV curve
CharacterizationCharacterizationSolar cell/modules characterization
IV curve: use callibration cell with same spectral response
or, if one knows spectral response of sample and reference cell andspectral irradiance of solar simulator, one may calculate themismatch error:
C.H. Seaman, Calibration of Solar Cells by the Reference CellMethod - The Spectral Mismatch Problem , Solar Energy, vol. 29, No.4, 1982, pp. 291-298
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IV curve
Class A Class B Class C
Spectral match 0.75 1.25% 0.6 1.4% 0.4 2.0%
IEC 904-9 : Requirements for solar simulators forcrystalline Si single-junction devices
Non-uniformity
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IV dark curve
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CharacterizationCharacterizationSolar cell/modules characterization
Reflectance
Sample
Lightsource
Monochromator Chopper
Lock-in Aluminium sample(high reflectivity)Zero background(low reflectivity)
CharacterizationCharacterizationSolar cell/modules characterization
Reflectance
S. Lust, et al, Mono and multicrystalline silicon solar cells based on macroporous silicon, Proc.of the 17 th EPVSEC, Munich 2001
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LifetimeMost common technique: Micro Wave P hoto Conductance Decay
Excess carriersgenerated by light
pulse
Monitoring variationof microwave
D.M. Macdonald, Recombination and trapping in multicrystalline silicon solar cells , PhD Thesis, Australian National University, 2001
reflectivity
Calculation of lifetime from decay
time constant
CharacterizationCharacterizationSolar cell/modules characterization
Lifetime
J. A. Silva, et al, Solar cells on silicon ribbons doped with sprayed boric acid as a doping source, Proc. 23 rd EPVSEC, Valencia 2008
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LifetimeCritical issue for lifetime measurements: surface passivationMay be achieved by many different approaches:
Growth deposition of a dielectric film or pn junction (e.g. a-Si)Corona discharge on SiO 2 filmImmersion in hydrofluoric acid ( HF)or alcoholic iodine solution
D. Pera, et al, Reliability of microwave photoconductivity lifetime measurements, Proceedings of the 23 rd EPVSEC, Valencia 2008
CharacterizationCharacterizationSolar cell/modules characterization
INFRARED IMAGING
IncludesElectroluminescence (EL)photoluminescence (PL) andlock-in thermography (LIT).
Allows measurement of Series or shunt resistanceJunction breakdownHot spotsLifetime
Kasemann et al, Progress in silicon solar cell characterization with infrared imaging methods, Proc. of the 23 rd EPVSEC,Valencia 2008
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CharacterizationCharacterizationINFRARED IMAGING SETUP .
Homogeneous irradiation of theentire solar cell is typically performedwith lasers in the wavelength rangefrom 790nm to 940nm. Differentcameras can be used to detectradiation in different wavelengthranges.
Spectral range of photon emissionfrom silicon solar cells, the underlying
mechanisms, and the detectors used.
Kasemann et al, Progress in silicon solar cell characterization with infrared imaging methods, Proc. of the 23 rd EPVSEC,Valencia 2008
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DEGRADATION
TESTS
Thermal Cycling(10.6)
Visual Inspection(10.1)
Damp Heat
(10.7)
Wet Insulation(10.5)
UV
(10.15)Humidity Freeze
(10.8)
Wet Insulation(10.5)
Load Test
(10.13)
ElectricalInsulation (10.4)
Dry Insulation(10.4)
Visual Inspection(10.1)
Dry Insulation(10.4)
Visual Inspection(10.1)
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Degradation: THERMAL CYCLING
Maximum celltemperature ( C)
TotalCycles
Applied Current
85 1000 Apply 1,25xISC when T>25 C.
Cycle speed is 10electrical/thermal
110 500
65 2000
After the Thermal Cycling, modules should be subjected to
To identify anddetermine any physicalchanges or defects in
module
Determine whether ornot the concentratorsystem is sufficiently
well insulated betweenthe active parts in the
power generating circuitand the frame or the
outside world
Visual Inspection(10.1)
Electrical (or Dry) Insulation(10.4)
CharacterizationCharacterizationSolar cell/modules characterization
Degradation: DAMP HEAT
After the Damp heat, modules should be subjected to
Relative humidity should be controlled to 85 % 5% and the temperature to 85 C 2 C for 1000h.
The test should be continued for up an additional 60h to permit the insulation test to be performed.
To determine the ability of the modules or assemblies to withstand the effects of long term penetration of humidity.
To evaluate the insulation of theconcentrator system under wetoperating conditions and verify
that moisture from rain, fog, dewor melted snow does not enterthe active parts of the sample
Wet insulation(10.5)
Visual Inspection (10.1)
Electrical (or Dry) Insulation(10.4)