1、Designation: E2236 10Standard Test Methods forMeasurement of Electrical Performance and SpectralResponse of Nonconcentrator Multijunction PhotovoltaicCells and Modules1This standard is issued under the fixed designation E2236; the number immediately following the designation indicates the year ofori
2、ginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods provide special techniques needed todetermi
3、ne the electrical performance and spectral response oftwo-terminal, multijunction photovoltaic (PV) devices, bothcell and modules.1.2 These test methods are modifications and extensions ofthe procedures for single-junction devices defined by TestMethods E948, E1021, and E1036.1.3 These test methods
4、do not include temperature andirradiance corrections for spectral response and current-voltage(I-V) measurements. Procedures for such corrections are avail-able in Test Methods E948, E1021, and E1036.1.4 These test methods may be applied to cells and modulesintended for concentrator applications.1.5
5、 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-p
6、riate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E772 Terminology Relating to Solar Energy ConversionE927 Specification for Solar Simulation for PhotovoltaicTestingE948 Test Method for Electrical Perf
7、ormance of Photovol-taic Cells Using Reference Cells Under Simulated SunlightE973 Test Method for Determination of the Spectral Mis-match Parameter Between a Photovoltaic Device and aPhotovoltaic Reference CellE1021 Test Method for Spectral Responsivity Measure-ments of Photovoltaic DevicesE1036 Tes
8、t Methods for Electrical Performance of Noncon-centrator Terrestrial Photovoltaic Modules and ArraysUsing Reference CellsE1040 Specification for Physical Characteristics of Non-concentrator Terrestrial Photovoltaic Reference CellsE1125 Test Method for Calibration of Primary Non-Concentrator Terrestr
9、ial Photovoltaic Reference Cells Us-ing a Tabular SpectrumE1328 Terminology Relating to Photovoltaic Solar EnergyConversionE1362 Test Method for Calibration of Non-ConcentratorPhotovoltaic Secondary Reference CellsG138 Test Method for Calibration of a SpectroradiometerUsing a Standard Source of Irra
10、dianceG173 Tables for Reference Solar Spectral Irradiances: Di-rect Normal and Hemispherical on 37 Tilted Surface3. Terminology3.1 Definitionsdefinitions of terms used in this standardmay be found in Terminology E772 and in TerminologyE1328.3.2 Definitions of Terms Specific to This Standard:3.2.1 mu
11、ltijunction device, na photovoltaic device com-posed of more than one photovoltaic junction stacked on top ofeach other and electrically connected in series.3.2.2 component cells, nthe individual photovoltaic junc-tions of a multijunction device.3.3 Symbols:C = reference cell calibration constant un
12、der the ref-erence spectrum, Am2W1Eo= total irradiance of reporting conditions, Wm2ES(l) = source spectral irradiance, Wm2nm1orWm2m11These test methods are under the jurisdiction of ASTM Committee E44 onSolar, Geothermal and Other Alternative Energy Sources and is the direct respon-sibility of Subco
13、mmitteeE44.09 on Photovoltaic Electric Power Conversion.Current edition approved June 1, 2010. Published July 2010. Originally approvedin 2002. Last previous edition approved in 2005 as E223605a. DOI: 10.1520/E2236-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AS
14、TM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.ER(l) = reference spectral i
15、rradiance, Wm2nm1orWm2m1FF = fill factor, dimensionlessi = subscript index associated with an individualcomponent cellIo= current of test device under the reference spec-trum, AI = current of test device under the source spectrum,AIsc= short-circuit current, AIR= short-circuit current of reference c
16、ell under thesource spectrum, AM = spectral mismatch parameter, dimensionlessn = number of component cells in the multijunctiondevicePmax= maximum power, WQ(l) = quantum efficiency, dimensionlessR(l) = spectral response, AW1RT(l) = test device spectral response, AW1RR(l) = reference cell spectral re
17、sponse, AW1T = temperature, CVoc= open-circuit voltage, VVb= voltage applied by dc bias source, VZ = current balance, dimensionlessl = wavelength, nm or m4. Significance and Use4.1 In a series-connected multijunction PV device, theincident total and spectral irradiance determines which com-ponent ce
18、ll will generate the smallest photocurrent and thuslimit the current through the entire series-connected device.This current-limiting behavior also affects the fill factor of thedevice. Because of this, special techniques are needed tomeasure the correct I-Vcharacteristics of multijunction devicesun
19、der the desired reporting conditions (see Test MethodsE1036).4.2 These test methods use a numerical parameter called thecurrent balance which is a measure of how well the testconditions replicate the desired reporting conditions. When thecurrent balance deviates from unity by more than 0.03, theunce
20、rtainty of the measurement may be increased.4.3 The effects of current limiting in individual componentcells can cause problems for I-V curve translations to differenttemperature and irradiance conditions, such as the translationsrecommended in Test Methods E1036. For example, if adifferent componen
21、t cell becomes the limiting cell as theirradiance is varied, a discontinuity in the current versusirradiance characteristic may be observed. For this reason, it isrecommended that I-V characteristics of multijunction devicesbe measured at temperature and irradiance conditions close tothe desired rep
22、orting conditions.4.4 Some multijunction devices have more than two termi-nals which allow electrical connections to each componentcell. In these cases, the special techniques for spectral responsemeasurements are not needed because the component cells canbe measured individually. However, these I-V
23、 techniques arestill needed if the device is intended to be operated as atwo-terminal device.4.5 Using these test methods, the spectral response istypically measured while the individual component cell undertest is illuminated at levels that are less than Eo. Nonlinearityof the spectral response may
24、 cause the measured results todiffer from the spectral response at the illumination levels ofactual use conditions.5. Summary of Test Methods5.1 Spectral response measurements of the device under testare accomplished using light- and voltage-biasing techniquesof each component cell, followed by dete
25、rmination of thespectral response according to Test Methods E1021.5.2 If a spectrally adjustable solar simulator is available (see6.1.1) the electrical performance measurements use an iterativeprocess of adjusting the incident spectral irradiance until theoperating conditions are close to the desire
26、d reporting condi-tions is used. This adjustment modifies a quantity known as thecurrent balance. The I-V characteristics are then measuredaccording to Test Methods E948 or E1036. Appendix X1contains a derivation and discussion of current balance.5.3 For the case of light sources where the spectral
27、irradi-ance cannot be changed, such as outdoors or if a spectrallyadjustable solar simulator is not available, the I-V characteris-tics are measured according to Test Methods E948 or E1036.However, the current balance in each component cell must alsobe determined and reported.6. Apparatus6.1 In addi
28、tion to the apparatus required for Test MethodsE948, E973, E1021, E1036, and G138, these test methods referto the following apparatus.6.1.1 spectrally adjustable Solar SimulatorA solar simu-lator that meets the requirements of Specification E927 andwhich has the additional capability of allowing dif
29、ferentwavelength regions of its spectral irradiance to be indepen-dently adjusted. This may be accomplished by several meth-ods, such as a multisource simulator with independent sourcesfor different regions, or a multiple filter simulator.6.1.1.1 Ideally, the adjustable wavelength ranges of thespect
30、rally adjustable solar simulator should correspond to thespectral response ranges of each component cell in the multi-junction device to be tested.6.1.2 Reference CellsPhotovoltaic reference cells (seeSpecification E1040), calibrated according to Test MethodsE1125 or E1362, are used to measure sourc
31、e irradiance in thewavelength regions that correspond to each component cell inthe multijunction device to be tested. For best results, thespectral responses of the reference cells should be similar to thespectral responses of the corresponding component cells.6.1.3 Bias Light SourceAdc bias light a
32、s specified by TestMethods E1021, that is equipped with appropriate spectralfilters to block wavelength regions corresponding to theexpected spectral response range of the individual componentcell being tested.6.1.3.1 Acceptable alternatives to filtered light sources arecontinuous lasers that emit a
33、t single wavelengths in the spectralresponse ranges of each component cell. Ideally, the selectedlaser wavelengths should not illuminate regions where thespectral responses of any two component cells overlap.6.1.4 Bias Voltage SourceA variable dc power supplycapable of providing a voltage equal to t
34、he open-circuit voltageE2236 102of the multijunction device to be tested, and compatible withthe synchronous detection instrumentation of Test MethodsE1021.7. Procedure7.1 Spectral Response:7.1.1 Place the device under test in the spectral response testfixture.7.1.2 Select the component cell to be m
35、easured.7.1.3 Apply light bias to component cells not being mea-sured using the bias light source:7.1.3.1 Choose spectral filters whose spectral transmittance,when combined, corresponds to the spectral response of thecomponent cell or cells not being measured. Install the spectralfilters in front of
36、 the bias light source.7.1.3.2 If lasers are used, turn on the lasers that emitwavelengths corresponding to the component cell or cells notbeing measured.7.1.3.3 Ideally, the illumination on the component cell beingmeasured should be at Eoand the component cells not beingmeasured should be illuminat
37、ed at higher levels. Practically,the component cell to be measured should have some illumi-nation, as device spectral responsivities can be a function of theillumination level.7.1.3.4 Turn on the bias light source and illuminate, as aminimum, the region where the monochromatic beam illumi-nates the
38、test device.7.1.4 Measure the Vocof the test device.7.1.5 Calculate the bias voltage to use during the test:7.1.5.1 For devices with component cells that contributesimilar voltages, calculate the bias voltage according to Eq 1.Vb5n 2 1nVoc. (1)7.1.5.2 For devices with component cells contributing su
39、b-stantially different voltages, calculate the bias voltage as thesum of the expected voltage contributions from the componentcells not being measured.7.1.6 Set the Vbon the bias voltage source.7.1.7 Connect the test device to the ac measurement instru-mentation.7.1.8 Maximize the ac signal from the
40、 component cell undertest using a wavelength at which it is expected to respond:7.1.8.1 Set the monochromatic light source to a wavelengthin the expected spectral response region of the component cellto be measured.7.1.8.2 Adjust the bias light intensity to saturate or maxi-mize the test device sign
41、al.7.1.9 Minimize the test device signal at wavelengths wherethe component cells not being measured are expected torespond:7.1.9.1 Set the monochromatic light source for a wavelengthin the expected spectral response region of the component cellnot being measured.7.1.9.2 Minimize or zero the test dev
42、ice signal by adjustingthe bias light intensity.7.1.9.3 Repeat 7.1.9.1 and 7.1.9.2 for additional componentcells not being measured, if any.7.1.10 As in 7.1.8 and 7.1.9, adjust Vbto further maximizethe signal in 7.1.8 and further minimize the signal in 7.1.9.7.1.11 Select light bias and voltage bias
43、 levels that bothmaximize the signal in 7.1.8 and minimize the signal in 7.1.9.The signal in 7.1.9 should correspond to a quantum efficiency,Q(l), that is less than 0.01 in wavelength regions where thecomponent cell being measured is known to have no response.7.1.12 It may be necessary to adjust the
44、 bias light source in7.1.3 to obtain a light bias condition that satisfies 7.1.11.7.1.13 Measure the relative spectral response of the compo-nent cell being tested according to Test Methods E1021.7.1.14 Repeat 7.1.2-7.1.13 for each component cell of themultijunction device under test.7.2 Electrical
45、Performance, spectrally adjustable SolarSimulator:7.2.1 Adjust the total irradiance of the spectrally adjustablesolar simulator to a level close to the desired reportingconditions using a reference cell or previous experience (thisinitial irradiance level is not critical).7.2.2 Measure the spectral
46、irradiance of the spectrally ad-justable solar simulator with a spectroradiometer calibratedaccording to Test Method G138.7.2.3 Calculate the spectral mismatch parameter, Mi, foreach component cell in the multijunction device under testusing the spectral responses obtained in 7.1, the reference cell
47、spectral responses, the spectral irradiance measured in 7.2.2,and the desired reference spectral irradiance (such as TablesG173).7.2.4 Measure the Iscof each reference cell under thespectrally adjustable solar simulator, IRi, in the same test planeas the multijunction device under test.7.2.5 Calcula
48、te the current balance, Zi, for each componentcell in the multijunction device under test using the followingequation:Zi51MiEOCiIRi(2)7.2.6 If the current balance for each cell is within1.0060.03, the spectrally adjustable solar simulator is adjustedto within reasonable limits. If not, adjust the sp
49、ectral irradianceand repeat 7.2.2-7.2.5.7.2.6.1 Ideally, to minimize spectral errors, each currentbalance should be within 1.0060.01, although the number ofiterations required to obtain this degree of balance may beprohibitive.7.2.6.2 It should be noted that for intermediate iterations, itis possible to omit the spectral irradiance measurement of 7.2.2and substitute the spectral irradiance measured for previousiterations, especially if only small changes have been made.However, the measurement should not be omitted for the finaliteration of 7.2.
