1、Designation: E 1125 05Standard Test Method forCalibration of Primary Non-Concentrator TerrestrialPhotovoltaic Reference Cells Using a Tabular Spectrum1This standard is issued under the fixed designation E 1125; the number immediately following the designation indicates the year oforiginal adoption o
2、r, 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 This test method is intended to be used for calibrationand characterization o
3、f primary terrestrial photovoltaic refer-ence cells to a desired reference spectral irradiance distribu-tion, such as Tables G 173. The recommended physical re-quirements for these reference cells are described inSpecification E 1040. Reference cells are principally used inthe determination of the e
4、lectrical performance of photovoltaicdevices.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
5、requires the use of a pyranometer thatis calibrated according to Test Method E 816, 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 E 1362. 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 t
7、est 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 E 1143.1.6 This test method applies only to the calibration of areference cell fabricated with a single
8、photovoltaic junction.1.7 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
9、to use.2. Referenced Documents2.1 ASTM Standards:2E 772 Terminology Relating to Solar Energy ConversionE 816 Test Method for Calibration of Pyrheliometers byComparison to Reference PyrheliometersE 948 Test Methods for Electrical Performance of Non-Concentrator Terrestrial Photovoltaic Cells Using Re
10、fer-ence CellsE 973 Test Method for Determination of the Spectral Mis-match Between a Photovoltaic Device and a PhotovoltaicReference CellE 1021 Test Methods for Measuring the Spectral Responseof Photovoltaic CellsE 1039 Test Method for Calibration and Characterization ofNon-Concentrator Terrestrial
11、 Photovoltaic Reference CellsUnder Global IrradiationE 1040 Specification for Physical Characteristics of Non-Concentrator Terrestrial Photovoltaic Reference CellsE 1328 Terminology Relating to Photovoltaic Solar EnergyConversionE 1362 Test Method for Calibration of Non-ConcentratorPhotovoltaic Seco
12、ndary Reference CellsG 173 Tables for Reference Solar Spectral Irradiances:Direct Normal and Hemispherical on 37 Tilted Surface3. Terminology3.1 DefinitionsDefinitions of terms used in this testmethod may be found in Terminology E 772 and TerminologyE 1328.3.2 Symbols:3.2.1 The following symbols and
13、 units are used in this testmethod:lWavelength, nm or m,IscShort-circuit current, A,EIrradiance, Wm2,EtTotal irradiance, Wm2,E(l)Spectral irradiance, Wm2m1,1This test method is under the jurisdiction of ASTM Committee E44 on Solar,Geothermal, and OtherAlternative Energy Sources and is the direct res
14、ponsibility ofSubcommittee E44.09 on Photovoltaic Electric Power Conversion.Current edition approved April 1, 2005. Published May 2005. Originallyapproved in 1986. Last previous edition approved in 1999 as E 1125 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM
15、 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.R(l)Spectral response, AW1,Rr(
16、l)Reference cell spectral response, AW1,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 prima
17、ry 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 to t
18、he spectral mismatch parameter defined inTest Method E 973, 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 irr
19、adiance measurement instrumentas specified in Test Method E 973.4.2 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 E 1021.4.2.2 The c
20、ells 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 1
21、143.4.2.4 The fill factor of the reference cell is determined usingTest Method E 948. Providing the fill factor with the calibra-tion data allows the reference cell to be checked in the futurefor electrical degradation or damage.5. Significance and Use5.1 The electrical output of a photovoltaic devi
22、ce 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 t
23、hat 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. Thes
24、e errors are accounted for by thespectral mismatch parameter (described inTest Method E 973),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 calibrat
25、ion 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 G 173. T
26、his 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 E 1040.5.5 Be
27、cause 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 Pyrh
28、eliometer A secondary reference pyrheliometerthat is calibrated in accordance with Test Method E 816.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 cali
29、bration 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 Equipmen
30、t,asre-quired by Test Method E 973.6.3.1 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 t
31、hepyrheliometer 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 G 173,to supply the missing wavelengths. The reference spectrum isscaled to match the measured spectr
32、al irradiance 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 fi
33、eld-of-view 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.T
34、he pyrheliometer 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
35、a resolution 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 positionE1125052that minimizes any temperature gradients between the sensorand the photovoltaic device junction.6.6
36、 Electrical 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 le
37、ss than 0.1 % of the maximum current or voltageencountered.6.7 Spectral Response Measurement Equipment, as requiredby Test Method E 1021.6.7.1 The wavelength interval between spectral responsedata points shall be a maximum of 50 nm.6.8 Temperature Control Block (Optional)A device tomaintain the temp
38、erature 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
39、.7.2 Characterize 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 MethodsE 1021.7.2.2 Temperature CoeffcientDetermine the
40、temperaturecoefficient, 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 s
41、econd reference 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 cell
42、s Iscby its 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 LinearityDeter
43、mine the short-circuit current versusirradiance linearity of the cell being calibrated in accordancewith Test Method E 1143 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, t
44、he short-circuit 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 E 948.8. Procedure8.1 Mount the reference cell to be calibrated, the co
45、llimator,the 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 E 973. During the spectralirradiance mea
46、surement, perform 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
47、times. Theserepetitions 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
48、 8.2.4 to obtain 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 da
49、ta set for thecalibration.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 E 973. To perform this calculation, replacethe reference cell spectral response R
