1、Designation: E1125 10Standard Test Method forCalibration of Primary Non-Concentrator TerrestrialPhotovoltaic Reference Cells Using a Tabular Spectrum1This standard is issued under the fixed designation E1125; the number immediately following the designation indicates the year oforiginal adoption or,
2、 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 This test method is intended to be used for calibrationand characterization of p
3、rimary terrestrial photovoltaic refer-ence cells to a desired reference spectral irradiance distribu-tion, such as Tables G173. The recommended physical require-ments for these reference cells are described in SpecificationE1040. Reference cells are principally used in the determina-tion of the elec
4、trical performance of photovoltaic devices.1.2 Primary photovoltaic reference cells are calibrated innatural sunlight using the relative spectral response of the cell,the relative spectral distribution of the sunlight, and a tabulatedreference spectral irradiance distribution.1.3 This test method re
5、quires the use of a pyrheliometer thatis calibrated according to Test Method E816, which requiresthe use of a pyrheliometer that is traceable to the WorldRadiometric Reference (WRR). Therefore, reference cellscalibrated according to this test method are traceable to theWRR.1.4 This test method is a
6、technique that may be used insteadof the procedures found in Test Method E1362. This testmethod offers convenience in its ability to characterize areference cell under any spectrum for which tabulated data areavailable. The selection of the specific reference spectrum isleft to the user.1.5 This tes
7、t method applies only to the calibration of aphotovoltaic cell that shows a linear dependence of its short-circuit current on irradiance over its intended range of use, asdefined in Test Method E1143.1.6 This test method applies only to the calibration of areference cell fabricated with a single pho
8、tovoltaic junction.1.7 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.8 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 standar
9、d 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:2E772 Terminology Relating to Solar Energy ConversionE816 Test Method for Calibration of Pyrheliometers byComparison to Reference
10、PyrheliometersE948 Test Method for Electrical Performance 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 Responsiv
11、ity Measure-ments of Photovoltaic DevicesE1040 Specification for Physical Characteristics of Non-concentrator Terrestrial Photovoltaic Reference CellsE1328 Terminology Relating to Photovoltaic Solar EnergyConversionE1362 Test Method for Calibration of Non-ConcentratorPhotovoltaic Secondary Reference
12、 CellsG173 Tables for Reference Solar Spectral Irradiances: Di-rect Normal and Hemispherical on 37 Tilted Surface3. Terminology3.1 DefinitionsDefinitions of terms used in this testmethod may be found in Terminology E772 and TerminologyE1328.3.2 Symbols:3.2.1 The following symbols and units are used
13、in this testmethod:lWavelength, nm or m,IscShort-circuit current, A,EIrradiance, Wm2,EtTotal irradiance, Wm2,E(l)Spectral irradiance, Wm2m1,R(l)Spectral response, AW1,Rr(l)Reference cell spectral response, AW1,1This test method is under the jurisdiction of ASTM Committee E44 on Solar,Geothermal and
14、OtherAlternative Energy Sources and is the direct responsibility ofSubcommittee E44.09 on Photovoltaic Electric Power Conversion.Current edition approved June 1, 2010. Published July 2010. Originally approvedin 1986. Last previous edition approved in 2005 as E1125 05. DOI: 10.1520/E1125-10.2For refe
15、renced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM 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, Wes
16、t Conshohocken, PA 19428-2959, United States.TTemperature, C,aTemperature coefficient of reference cell Isc,C1,nTotal number of data points,CCalibration constant, Am2W1,MSpectral mismatch parameter,FSpectral correction factor, andSStandard deviation.4. Summary of Test Method4.1 The calibration of a
17、primary photovoltaic reference cellconsists of measuring the short-circuit current of the cell whenilluminated with natural sunlight, along with the total solarirradiance using a pyrheliometer. The ratio of the short-circuitcurrent of the cell to the irradiance, divided by a correctionfactor similar
18、 to the spectral mismatch parameter defined inTest Method E973, is the calibration constant for the referencecell. Also, if the temperature of the cell is not 25 6 1C, theshort-circuit current must be corrected to 25C.4.1.1 The relative spectral irradiance of the sunlight ismeasured using a spectral
19、 irradiance measurement instrumentas specified in Test Method E973.4.2 The following is a list of measurements that are used tocharacterize reference cells and are reported with the calibra-tion data:4.2.1 The spectral response of the cell is determined inaccordance with Test Methods E1021.4.2.2 The
20、 cells short-circuit current temperature coefficientis determined experimentally by measuring the short-circuitcurrent at various temperatures and computing the temperaturecoefficient (see 7.2.2).4.2.3 Linearity of short-circuit current versus irradiance isdetermined in accordance with Test Method E
21、1143.4.2.4 The fill factor of the reference cell is determined usingTest Method E948. Providing the fill factor with the calibrationdata allows the reference cell to be checked in the future forelectrical degradation or damage.5. Significance and Use5.1 The electrical output of a photovoltaic device
22、 is depen-dent on the spectral content of the illumination source, itsintensity, and the device temperature. To make standardized,accurate measurements of the performance of photovoltaicdevices under a variety of light sources, it is necessary toaccount for the error in the short-circuit current tha
23、t occurs ifthe relative spectral response of the reference cell is notidentical to the spectral response of the device to be tested. Asimilar error occurs if the spectral irradiance distribution of thetest light source is not identical to the desired reference spectralirradiance distribution. These
24、errors are accounted for by thespectral mismatch parameter (described in Test Method E973),a quantitative measure of the error in the short-circuit currentmeasurement. It is the intent of this test method to provide arecognized procedure for calibrating, characterizing, and re-porting the calibratio
25、n data for primary photovoltaic referencecells using a tabular reference spectrum.5.2 The calibration of a reference cell is specific to aparticular spectral irradiance distribution. It is the responsibil-ity of the user to specify the applicable irradiance distribution,for example Tables G173. This
26、 test method allows calibrationwith respect to any tabular spectrum.5.3 A reference cell should be recalibrated at yearly inter-vals, or every six months if the cell is in continuous useoutdoors.5.4 Recommended physical characteristics of referencecells can be found in Specification E1040.5.5 Becaus
27、e silicon solar cells made on p-type substrates aresusceptible to a loss of Iscupon initial exposure to light, it isrequired that newly manufactured reference cells be lightsoaked at an irradiance level greater than 850 W/m2for2hprior to initial characterization in Section 7.6. Apparatus6.1 Pyrhelio
28、meter A secondary reference pyrheliometerthat is calibrated in accordance with Test Method E816.Anabsolute cavity radiometer may also be used. Because second-ary reference pyrheliometers are calibrated against an absolutecavity radiometer, the total uncertainty in the primary referencecell calibrati
29、on constant will be reduced if an absolute cavityradiometer is used.6.2 CollimatorA collimator fitted to the reference cellduring calibration that has the same field-of-view as thepyrheliometer. An acceptable collimator design is described inAnnex A1.6.3 Spectral Irradiance Measurement Equipment,asr
30、e-quired by Test Method E973.6.3.1 The spectral range of the spectral irradiance measure-ment shall be wide enough to include the spectral response ofthe cell to be calibrated.6.3.2 The spectral range of the spectral irradiance measure-ment shall include 98 % of the total irradiance to which thepyrh
31、eliometer is sensitive.6.3.3 If the spectral irradiance measurement is unable tomeasure the entire wavelength range required by 6.3.2,itisacceptable to use a reference spectrum, such as Tables G173,tosupply the missing wavelengths. The reference spectrum isscaled to match the measured spectral irrad
32、iance data over aconvenient wavelength interval within the wavelength range ofthe spectral irradiance measurement equipment. It is alsoacceptable to calculate the missing spectral irradiance datausing a numerical model.6.3.4 The spectral irradiance measurement equipment shallhave the same field-of-v
33、iew as the pyrheliometer and thereference cell collimator.6.4 Normal Incidence Tracking PlatformsTracking plat-forms used to follow the sun during the calibration and to holdthe reference cell to be calibrated, the pyrheliometer, thecollimator, and spectral irradiance measurement equipment.The pyrhe
34、liometer and the collimator must be parallel within60.25. The platforms shall be able to track the sun within60.5 during the calibration procedure.6.5 Temperature Measurement EquipmentAn instrumentor instruments used to measure the temperature of the referencecell to be calibrated, that has a resolu
35、tion of at least 0.1C, anda total error of less than 61C of reading.6.5.1 Sensors such as thermocouples or thermistors used forthe temperature measurements must be located in a positionE1125 102that minimizes any temperature gradients between the sensorand the photovoltaic device junction.6.6 Electr
36、ical Measurement EquipmentVoltmeters, am-meters, or other suitable electrical measurement instruments,used to measure the Iscof the cell to be calibrated and thepyrheliometer output, that have a resolution of at least 0.02 %of the maximum current or voltage encountered, and a totalerror of less than
37、 0.1 % of the maximum current or voltageencountered.6.7 Spectral Response Measurement Equipment, as requiredby Test Method E1021.6.7.1 The wavelength interval between spectral responsedata points shall be a maximum of 50 nm.6.8 Temperature Control Block (Optional)A device tomaintain the temperature
38、of the reference cell at 25 6 1C forthe duration of the calibration.7. Characterization7.1 Prior to the characterization measurements, illuminatethe reference cell to be calibrated at 1000 Wm2for 2 h. Thisis necessary to stabilize any light-induced degradation of thecell prior to calibration.7.2 Cha
39、racterize the reference cell being calibrated by thefollowing methods:7.2.1 Spectral ResponseDetermine the relative spectralresponse, R(l), (optionally the absolute spectral response) ofthe cell to be calibrated in accordance with Test MethodsE1021.7.2.2 Temperature CoeffcientDetermine the temperatu
40、recoefficient, a, of the cell to be calibrated as follows:7.2.2.1 Using the electrical measurement equipment, mea-sure Iscat four or more temperatures over at least a 50Ctemperature range centered around 35C. The irradiance shallbe at least 750 Wm2and less than 1100 Wm2, as measuredwith a second ref
41、erence cell. Measure the temperature of thebeing calibrated at the same time.7.2.2.2 Divide each value of Iscby the normalized instanta-neous irradiance level at the time of each measurement.NOTE 1The normalized instantaneous irradiance can be determinedby dividing the second reference cells Iscby i
42、ts calibration constant.7.2.2.3 Determine the temperature coefficient by performinga least-squares fit of the Iscversus T data to a straight line. Theslope of the line divided by the value of the current from theleast-squares fit at 25C is the temperature coefficient, a.7.2.3 LinearityDetermine the
43、short-circuit current versusirradiance linearity of the cell being calibrated in accordancewith Test Method E1143 for the irradiance range 750 to 1100Wm2.7.2.3.1 For reference cells that use single-crystal siliconsolar cells, or for reference cells that have been previouslycharacterized, the short-c
44、ircuit current versus irradiance linear-ity determination is optional.7.2.4 Fill Factor Determine the fill factor of the cell to becalibrated from the I-V curve of the device, as measured inaccordance with Test Methods E948.8. Procedure8.1 Mount the reference cell to be calibrated, the collimator,th
45、e pyrheliometer, and the spectral irradiance measurementequipment on the tracking platforms.8.2 Measure the relative spectral irradiance of the sun, E(l),using the spectral irradiance measurement instrument (see 6.6)and the procedure of Test Method E973. During the spectralirradiance measurement, pe
46、rform the following:8.2.1 Measure the pyrheliometer output, Et, and verify thatthe total irradiance is between 750 Wm2and 1100 Wm2.8.2.2 Measure the short-circuit current of the reference cell,Isc.8.2.3 Measure the reference cell temperature, T.8.2.4 Repeat 8.2.1 and 8.2.2 at least four times. These
47、repetitions must be distributed in time during the spectralirradiance measurement. To assure temporal stability, theshort-circuit current of the reference cell shall not vary by morethan 60.2 % during the repetitions.8.2.5 Average the short-circuit current and total irradiancevalues from 8.2.4 to ob
48、tain the Iscand Etthat corresponds to thespectral irradiance measurement.8.3 Perform a minimum of five replications of 8.2.8.3.1 The five replications must be performed on at leastthree separate days. Therefore, five replications all performedon the same day would not be an acceptable data set for t
49、hecalibration.8.3.2 In order to reduce precision errors through averaging,it is recommended that at least 30 replications of 8.2 beperformed.9. Calculation of Results9.1 Each spectral irradiance measurement obtained in 8.2defines one data point. The total number of these data points isdenoted as n.9.1.1 For each data point, calculate the spectral correctionfactor, F, using the spectral mismatch parameter calculation,8.1, of Test Method E973. To perform this calculation, replacethe reference cell spectral response Rr(l) with u
