1、Designation: E 2236 05aStandard Test Methods forMeasurement of Electrical Performance and SpectralResponse of Nonconcentrator Multijunction PhotovoltaicCells and Modules1This standard is issued under the fixed designation E 2236; the number immediately following the designation indicates the year of
2、original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods provide special techniques needed todet
3、ermine 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 E 948, E 1021, and E 1036.1.3 These test m
4、ethods 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 E 948, E 1021, and E 1036.1.4 These test methods apply only to nonconcentrator ter-restrial multijunction photovolta
5、ic cells and modules.1.5 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-priate safety and health practices and determine the applica-bility of regulatory limitations prior t
6、o use.2. Referenced Documents2.1 ASTM Standards:2E 772 Terminology Relating to Solar Energy ConversionE 927 Specification for Solar Simulation for TerrestrialPhotovoltaic TestingE 948 Test Method for Electrical Performance of Photovol-taic Cells Using Reference Cells Under Simulated SunlightE 973 Te
7、st Method for Determination of the Spectral Mis-match Parameter Between a Photovoltaic Device and aPhotovoltaic Reference CellE 1021 Test Methods for Measuring Spectral Response ofPhotovoltaic CellsE 1036 Test Methods for Electrical Performance of Non-concentrator Terrestrial Photovoltaic Modules an
8、d ArraysUsing Reference CellsE 1040 Specification for Physical Characteristics of Non-concentrator Terrestrial Photovoltaic Reference CellsE 1125 Test Method for Calibration of Primary Non-Concentrator Terrestrial Photovoltaic Reference Cells Us-ing a Tabular SpectrumE 1328 Terminology Relating to P
9、hotovoltaic Solar EnergyConversionE 1362 Test Method for Calibration of Non-ConcentratorPhotovoltaic Secondary Reference CellsG 138 Test Method for Calibration of a SpectroradiometerUsing a Standard Source of IrradianceG 173 Tables for Reference Solar Spectral Irradiances:Direct Normal and Hemispher
10、ical on 37 Tilted Surface3. Terminology3.1 Definitionsdefinitions of terms used in this standardmay be found in Terminology E 772 and in TerminologyE 1328.3.2 Definitions of Terms Specific to This Standard:3.2.1 multijunction device, na photovoltaic device com-posed of more than one photovoltaic jun
11、ction 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 under the ref-erence spectrum, Am2W1Eo= total irradiance of reporting conditions, Wm2ES(
12、l) = source spectral irradiance, Wm2nm1orWm2m1ER(l) = reference spectral irradiance, Wm2nm1orWm2m1FF = fill factor, dimensionless1These test methods are under the jurisdiction of ASTM Committee E44 onSolar, Geothermal and Other Alternative Energy Sources and is the direct respon-sibility of Subcommi
13、tteeE44.09 on Photovoltaic Electric Power Conversion.Current edition approved Sept. 1, 2005. Published October 2005. Originallyapproved in 2002. Last previous edition approved in 2005 as E 223605.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
14、 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.i = subscript index associated with an individualc
15、omponent 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 cell under thesource spectrum, AM = spectral mismatch parameter, dimensionlessn = number of component cell
16、s in the multijunctiondevicePmax= maximum power, WQ(l) = quantum efficiency, dimensionlessR(l) = spectral response, AW1RT(l) = test device spectral response, AW1RR(l) = reference cell spectral response, AW1T = temperature, CVoc= open-circuit voltage, VVb= voltage applied by dc bias source, VZ = curr
17、ent 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 cell will generate the smallest photocurrent and thuslimit the current through the entire series-connected
18、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 devicesunder the desired reporting conditions (see Test MethodsE 1036).4.2 These test methods use a numerical para
19、meter 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, theuncertainty of the measurement may be increased.4.3 The effects of current limiting in individual componentc
20、ells can cause problems for I-V curve translations to differenttemperature and irradiance conditions, such as the translationsrecommended in Test Methods E 1036. For example, if adifferent component cell becomes the limiting cell as theirradiance is varied, a discontinuity in the current versusirrad
21、iance 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 reporting conditions.4.4 Some multijunction devices have more than two termi-nals which allow electrical c
22、onnections 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 techniques arestill needed if the device is intended to be operated as atwo-terminal device.4.5 Using
23、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 cause the measured results todiffer from the spectral response at the illumination levels ofactual use
24、 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 determination of thespectral response according to Test Methods E 1021.5.2 If a spectrally adjustable solar
25、 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 desired reporting condi-tions is used. This adjustment modifies a quantity known as thecurrent balance. The
26、I-V characteristics are then measuredaccording to Test Methods E 948 or E 1036. Appendix X1contains a derivation and discussion of current balance.5.3 For the case of light sources where the spectral irradi-ance cannot be changed, such as outdoors or if a spectrallyadjustable solar simulator is not
27、available, the I-V characteris-tics are measured according to Test Methods E 948 or E 1036.However, the current balance in each component cell must alsobe determined and reported.6. Apparatus6.1 In addition to the apparatus required for Test MethodsE 948, E 973, E 1021, E 1036, and G 138, these test
28、 methodsrefer to the following apparatus.6.1.1 spectrally adjustable Solar SimulatorA solar simu-lator that meets the requirements of Specification E 927 andwhich has the additional capability of allowing differentwavelength regions of its spectral irradiance to be indepen-dently adjusted. This may
29、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 thespectrally adjustable solar simulator should correspond to thespectral response ranges of each co
30、mponent cell in the multi-junction device to be tested.6.1.2 Reference CellsPhotovoltaic reference cells (seeSpecification E 1040), calibrated according to Test MethodsE 1125 or E 1362, are used to measure source irradiance in thewavelength regions that correspond to each component cell inthe multij
31、unction 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 as specified by TestMethods E 1021, that is equipped with appropriate spectralfilters to b
32、lock 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 at single wavelengths in the spectralresponse ranges of each component cell. Ideally, the
33、 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 the open-circuit voltageE 2236 05a2of the multijunction device to be tested, and compatib
34、le withthe synchronous detection instrumentation of Test MethodsE 1021.7. 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 measured.7.1.3 Apply light bias to component cells not being mea-sured using the bias
35、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 the bias light source.7.1.3.2 If lasers are used, turn on the lasers that emitwavele
36、ngths 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 illuminated at higher levels. Practically,the component cell to be measured should have some i
37、llumi-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 test device.7.1.4 Measure the Vocof the test device.7.1.5 Calculate the bias voltage
38、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 sub-stantially different voltages, calculate the bias voltage as thesum of the expected
39、 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 component cell undertest using a wavelength at which it is expected to respond:7.1.8
40、.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 signal.7.1.9 Minimize the test device signal at wavelengths wherethe component cells not
41、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 device signal by adjustingthe bias light intensity.7.1.9.3 Repeat 7.1.9.1 and 7.1.9.2 fo
42、r 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 levels that bothmaximize the signal in 7.1.8 and minimize the signal in 7.1.9.The si
43、gnal 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 bias light source in7.1.3 to obtain a light bias condition that satisfies 7.1.11.7.1
44、.13 Measure the relative spectral response of the compo-nent cell being tested according to Test Methods E 1021.7.1.14 Repeat 7.1.2-7.1.13 for each component cell of themultijunction device under test.7.2 Electrical Performance, spectrally adjustable SolarSimulator:7.2.1 Adjust the total irradiance
45、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 irradiance of the spectrally ad-justable solar simulator with a spectroradiometer ca
46、libratedaccording to Test Method G 138.7.2.3 Calculate the spectral mismatch parameter, Mi, foreach component cell in the multijunction device under testusing the spectral responses obtained in 7.1, the reference cellspectral responses, the spectral irradiance measured in 7.2.2,and the desired refer
47、ence spectral irradiance (such as TablesG 173).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 Calculate the current balance, Zi, for each componentcell in the multijunction device und
48、er 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 spectral irradianceand repeat 7.2.2-7.2.5.7.2.6.1 Ideally, to minimize spectral erro
49、rs, 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 7.2.2-7.2.5.7.2.7 Mount the multijunction device under test in the I-Vmeasurement test
