1、Designation: E948 15Standard Test Method forElectrical Performance of Photovoltaic Cells UsingReference Cells Under Simulated Sunlight1This standard is issued under the fixed designation E948; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 This test method covers the determination of the elec-trical performance of a photovoltaic cell
3、under simulatedsunlight by means of a calibrated reference cell procedure.1.2 Electrical performance measurements are reported withrespect to a select set of standard reporting conditions (SRC)(see Table 1) or to user-specified conditions.1.2.1 The SRC or user-specified conditions include the cellte
4、mperature, the total irradiance, and the reference spectralirradiance distribution.1.3 This test method is applicable only to photovoltaic cellswith a linear response over the range of interest.1.4 The cell parameters determined by this test methodapply only at the time of test, and imply no past or
5、 futureperformance level.1.5 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 s
6、tandard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E490 Standard Solar Constant and Zero Air Mass SolarSpectral Irradiance TablesE491 Practice for Solar Simulation for Therma
7、l BalanceTesting of SpacecraftE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE772 Terminology of Solar Energy ConversionE927 Specification for Solar Simulation for PhotovoltaicTestingE973 Test Method for Determination of the Spectral Mis-match Paramet
8、er Between a Photovoltaic Device and aPhotovoltaic Reference CellE1125 Test Method for Calibration of Primary Non-Concentrator Terrestrial Photovoltaic Reference Cells Us-ing a Tabular SpectrumE1362 Test Method for Calibration of Non-ConcentratorPhotovoltaic Secondary Reference CellsG173 Tables for
9、Reference Solar Spectral Irradiances: DirectNormal and Hemispherical on 37 Tilted Surface3. Terminology3.1 DefinitionsDefinitions of terms in this test methodmay be found in Terminology E772.3.2 Definitions of Terms Specific to This Standard:3.2.1 cell temperature, C, nthe temperature of the semi-co
10、nductor junction of a photovoltaic cell.3.2.2 junction temperature, nsynonym for cell tempera-ture.3.2.3 light source, na source of radiant energy used forcell performance measurements that simulates natural sunlight.3.3 Symbols:3.3.1 The following symbols and units are used in this testmethod:Acell
11、 area, m2rtemperature coefficient of reference cell, C1Ccalibration constant of reference cell, Am2W1CTtransfer calibration ratio, dimensionlessEirradiance, Wm2Eostandard reporting irradiance, Wm2efficiency, %FFfill factor, %Icurrent, AImmonitor solar cell short-circuit current, AIocurrent with resp
12、ect to SRC, AIrreference cell short-circuit current, AIscshort-circuit current, AMspectral mismatch parameter, dimensionless1This test method is under the jurisdiction of ASTM Committee E44 on Solar,Geothermal and OtherAlternative Energy Sources and is the direct responsibility ofSubcommittee E44.09
13、 on Photovoltaic Electric Power Conversion.Current edition approved Feb. 1, 2015. Published March 2015. Originallyapproved in 1993. Last previous edition approved in 2009 as E948 09. DOI:10.1520/E0948-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Se
14、rvice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Pmmaximum power, WRsseries resistance, Ttem
15、perature, CTostandard reporting temperature, CTrtemperature of reference cell, CVvoltage, VVovoltage with respect to SRC, VVocopen-circuit voltage, V4. Summary of Test Method4.1 The performance test of a photovoltaic cell consists ofmeasuring the electrical current versus voltage (I-V) charac-terist
16、ic of the cell while illuminated by a suitable light source.4.2 Acalibrated photovoltaic reference cell (see 6.1) is usedto determine the total irradiance during the test and to accountfor the spectral distribution of the light source.4.3 Simulated sunlight is used as the light source for theelectri
17、cal performance measurement, and solar simulationrequirements are defined in Specification E927 (terrestrialapplications) and Practice E491 (space applications).4.4 The data from the measurements are corrected to stan-dard reporting conditions, or to optional user-specified report-ing conditions.The
18、 standard reporting conditions are defined inTable 1.34.4.1 Measurement error caused by deviations of the irradi-ance conditions from the SRC is corrected using the totalirradiance measured with the reference cell and the spectralmismatch parameter, M, which is determined in accordancewith Test Meth
19、od E973.4.4.2 Measurement error caused by deviation of the celltemperature from the SRC is minimized by maintaining the celltemperature close to the required value (see 7.10).5. Significance and Use5.1 It is the intent of this test method to provide a recog-nized method for testing and reporting the
20、 electrical perfor-mance of photovoltaic cells.5.2 The test results may be used for comparison of cellsamong a group of similar cells or to compare diverse designs,such as different manufacturers products. Repeated measure-ments of the same cell may be used to study changes in deviceperformance.5.3
21、This test method determines the electrical performanceof a cell based upon the output power at a single instant oftime. It does not provide for integrating the output power overa given period of time and conditions to predict an energyoutput.5.4 This test method requires a reference cell calibrated
22、withrespect to an appropriate reference spectral irradiancedistribution, such as Tables E490,orG173. It is the responsi-bility of the user to determine which reference spectralirradiance distribution is appropriate for a particular applica-tion.6. Apparatus6.1 Photovoltaic Reference CellAcalibrated
23、reference cellused to determine the total irradiance during the electricalperformance measurement.6.1.1 Reference cells may be calibrated in accordance withTest Methods E1125 or E1362, as is appropriate for a particularapplication.NOTE 1No reference cell calibration standards presently exist forspac
24、e applications, although procedures such as high-altitude balloon andlow-earth orbit flights are being used to calibrate such reference cells.6.1.2 The calibration constant, C, of the reference cell mustbe with respect to the reference spectral irradiance distributionof the desired SRC (see 1.2).6.1
25、.3 A current measurement instrument (see 6.3) shall beused to determine the Iscof the reference cell under the lightsource.6.2 Test FixtureBoth the cell to be tested and the referencecell are mounted in a fixture that meets the following require-ments.6.2.1 The test fixture shall ensure a uniform la
26、teral tempera-ture distribution to within 60.5C during the performancemeasurement.6.2.2 The test fixture shall include a provision for maintain-ing a constant cell temperature for both the reference cell andthe cell to be tested (see 7.10).NOTE 2When using pulsed or shuttered light sources, it is po
27、ssiblethat the cell temperature will increase upon initial illumination, even whenthe cell temperature is controlled.6.2.3 The test fixture, when placed in the simulated sunlight,shall ensure that the field-of-view of both the reference cell andthe cell to be tested are identical.NOTE 3Some solar si
28、mulators may have significant amounts ofirradiation from oblique or non-perpendicular angles to the test plane. Inthese cases, it is important that the cell to be tested and the reference cellhave similar reflectance and cosine-response characteristics.6.2.4 A four-terminal connection (also known as
29、 a Kelvinconnection, see Fig. 1) from the cell to be tested to the I-Vmeasurement instrumentation (see 6.3 6.5) shall be used.6.3 Current Measurement EquipmentElectrical instru-mentation used to measure the current through the cell undertest during the performance measurement. The instrumentationsha
30、ll have a resolution of at least 0.02 % of the maximumcurrent encountered, and shall have a total error of less than0.1 % of the maximum current encountered.6.3.1 The instrumentation shall be capable of simultane-ously measuring data points with the short-circuit current (see6.9) and voltage (see 6.
31、4) measurement equipment, to within10 s.3Wehrli, C., Extraterrestrial Solar Spectrum, Publ. No. 615, Physikalisch-Meteorologisches Observatorium and World Radiation Center, Davos Switzerland,1985.TABLE 1 Standard Reporting ConditionsReference Spectral IrradianceDistributionTotal Irradiance(Wm2)Tempe
32、rature(C)Tables G173 Direct Normal 1000 25Tables G173 Hemispherical 1000 25Tables E490 1366.1 25E948 1526.4 Voltage Measurement EquipmentElectrical instrumen-tation used to measure the voltage across the cell under testduring the performance measurement. The instrumentationshall have a resolution of
33、 at least 0.02 % of the maximumvoltage encountered, and shall have a total error of less than0.1 % of the maximum voltage encountered.6.4.1 The instrumentation shall be capable of simultane-ously measuring data points with the current (see 6.3) andshort-circuit current (see 6.9) measurement equipmen
34、t, towithin 10 s.6.5 Variable LoadAn electronic load, such as a variableresistor or a programmable power supply, used to operate thecell to be tested at different points along its I-V characteristic.6.5.1 The variable load shall be capable of operating the cellto be tested at an I-V point where the
35、voltage is within 1 % ofVocin the power-producing quadrant.6.5.2 The variable load shall be capable of operating the cellto be tested at an I-V point where the current is within 1 % ofIscin the power-producing quadrant.6.5.3 The variable load must allow an output power (theproduct of cell current an
36、d cell voltage) resolution of at least0.2 % of the maximum power.6.5.4 The electrical response time of the variable load mustbe fast enough to sweep the range of I-V operating pointsduring the measurement period.NOTE 4It is possible that the response time of the cell to be tested maylimit how fast t
37、he range of I-V operating points can be swept, especiallywhen pulsed solar simulators are used. For these cases, it may benecessary to measure smaller ranges of the I-V curve using multiplemeasurements to obtain the entire range required.6.6 Light SourceRequirements of the solar simulationused to il
38、luminate the cell to be tested are defined in Specifi-cation E927 (terrestrial applications) and Practice E491 (spaceapplications).6.7 Temperature Measurement EquipmentInstrumentationused to measure the cell temperatures of the reference cell, thecell to be tested, and the monitor solar cell shall h
39、ave aresolution of at least 0.1C, and shall have a total error of lessthan 61C of reading.6.7.1 Sensors used for the temperature measurement(s)must be located in a position that minimizes any temperaturegradients between the sensor and the photovoltaic devicejunction.6.7.2 Time constants associated
40、with these measurementsmust be less than 500 ms.6.8 Monitor Solar Cell (optional)An uncalibrated photo-voltaic solar cell that is positioned in the test plane such that itis illuminated by the light source during the performancemeasurement of the cell to be tested. The monitor solar cell isused to m
41、easure the irradiance during the performance mea-surement following a transfer-of-calibration procedure fromthe photovoltaic reference cell. It is also used to correct currentmeasurement data points of the cell to be tested for temporalinstability of the light source.6.8.1 The monitor solar cell may
42、 be positioned anywhere inthe test plane of the light source, but shall not be moved afterthe transfer-of-calibration procedure has been performed.6.8.2 The spectral responsivity of the monitor solar cell isunimportant, but the wavelength range of its responsivityshould include that of the cell to b
43、e tested. Crystalline-Si solarcells are recommended.6.8.3 The monitor solar cell shall be mounted on a testfixture that controls its cell temperature to within 61C duringthe performance measurement. It is recommended that themonitor solar cell have its own test fixture.6.8.4 The time constant of the
44、 monitor solar cells tempera-ture measurement must be less than 500 ms.6.9 Short-circuit Current Measurement EquipmentInstrumentation used to measure the Iscof the photovoltaicreference cell and the monitor solar cell.6.9.1 The instrumentation shall be capable of holding thevoltage across these cell
45、s to within 25 mV of zero.6.9.2 The instrumentation shall be capable of simultane-ously measuring current data points with the current (see 6.3)and voltage (6.4) measurement equipment, to within 10 s.7. Procedure7.1 Determine the series resistance, Rs, of the cell to bemeasured. An acceptable method
46、 is described in Annex A1.7.1.1 If the total irradiance during the performance mea-surement as measured by the reference cell is within 62%ofthe standard reporting total irradiance, the series resistance isnot needed.7.2 Measure the cell area, A, using the definition of area,photovoltaic cell in Ter
47、minology E772.7.3 Special CaseIf the cell to be tested also qualifies as areference cell according to 6.1 so that its C is known prior totest, the cell may be used to measure irradiance and theseparate reference cell omitted. The self-irradiance measure-ment technique is typically used to determine
48、the fill factor ofa reference cell post-calibration, and as a check for damage ordegradation.7.3.1 Set the spectral mismatch parameter, M, to one.7.3.2 Mount the cell to be tested in the test fixture.7.3.3 Proceed to 7.6.FIG. 1 I-V Measurement SchematicE948 1537.4 Determine the spectral mismatch par
49、ameter, M, usingTest Method E973.7.4.1 Test Method E973 requires four spectral quantities:the spectral responsivities of the cell under test and thereference cell, the spectral irradiance of the light source, andthe reference spectral irradiance distribution.7.4.2 Two of these quantities will be known prior to theperformance measurement: the reference cell spectral respon-sivity (required as part of its calibration data), and the referencespectral irradiance distribution (selected or specified before-hand in 1.2).7.
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