ASTM_E_1143_-_05_2015.pdf

Designation:E114305(Reapproved 2015)Standard Test Method forDetermining the Linearity of a Photovoltaic DeviceParameter with Respect To a Test Parameter1This standard is issued under the fixed designation E1143;the number immediately following the designation indicates the year oforiginal 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 This test method determines the degree of linearity of aphotovoltaic device parameter with respect to a test parameter,for example,short-circuit current with respect to irradiance.1.2 The linearity determined by this test method appliesonly at the time of testing,and implies no past or futureperformance level.1.3 This test method applies only to non-concentrator ter-restrial photovoltaic devices.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 to use.2.Referenced Documents2.1 ASTM Standards:2E772 Terminology of Solar Energy ConversionE948 Test Method for Electrical Performance of Photovol-taic Cells Using Reference Cells Under Simulated Sun-lightE1036 Test Methods for Electrical Performance of Noncon-centrator Terrestrial Photovoltaic Modules and ArraysUsing Reference CellsE1328 Terminology Relating to Photovoltaic Solar EnergyConversion(Withdrawn 2012)33.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,see Terminologies E772 and E1328.3.2 Definitions of Terms Specific to This Standard:3.2.1 photovoltaic device parametera characteristic of aphotovoltaic device,such as short-circuit current or open-circuit voltage.3.2.2 test parametera characteristic of the test conditionsto which the photovoltaic device is exposed,such as irradianceor temperature.3.3 Symbols:MeaningSymbolTest parameterXDevice parameterYNumber of data pairs takennSlope of the linear functionmFit to the dataEstimated variance of the slopes24.Summary of Test Method4.1 This test method requires the measurement of theparameters in question at or near the anticipated deviceoperating conditions.The number of measurements made mustbe sufficient to cover the range of operating conditions ex-pected.4.2 Device electrical parameters shall be measured in ac-cordance with Test Methods E948 or Methods E1036,which-ever is applicable.4.3 A linear function that passes through the origin is fit tothe data,and the deviation of these data from the function isused as the criterion for determining linearity.5.Significance and Use5.1 This test method is used to evaluate the applicability ofother ASTM test methods to a photovoltaic device.5.2 The procedure described in this test method is intendedto be used to determine the degree of linearity between theshort-circuit current of a photovoltaic device and the irradiancelevel incident on the device.This test method can be used forother device parameters,provided the function passes throughthe origin.1This 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 on Photovoltaic Electric Power Conversion.Current edition approved Nov.1,2015.Published November 2015.Originallyapproved in 1987.Last previous edition approved in 2005 as E1143-05(2010).DOI:10.1520/E1143-05R15.2For referenced 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Procedure6.1 Measure the device parameter for at least five values ofthe test parameter.Choose the values of the test parameter suchthat they span the expected operating range in approximatelyequal intervals.For determining the linearity of short-circuitcurrent with respect to irradiance,use four equally spacedirradiance intervals over the range of approximately 750 to1100 W/m2.6.1.1 All applicable electrical measurements must be per-formed in accordance with Test Methods E948 or MethodsE1036,whichever is applicable.7.Calculation47.1 The slope,m,of the linear function is calculated usingthe following equation:m 5(i51nXiYi/(i51nXi2(1)7.2 The estimated variance of the slope is given as follows:s25(i51nYi2 mXi!2/n 2 1!(i51nXi2(2)7.3 Device electrical parameters may be considered linearwith respect to the test parameter if the criterion is met asfollow