1、Designation: E2848 111E2848 13Standard Test Method forReporting Photovoltaic Non-Concentrator SystemPerformance1This standard is issued under the fixed designation E2848; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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 NOTEAnnex A1, Eq A1.5 was corrected editorially in September 2012.1. Scope1.1 This test method provides measurement and analysis
3、 procedures for determining the capacity of a specific photovoltaicsystem built in a particular place and in operation under natural sunlight.1.2 This test method is used for the following purposes:1.2.1 acceptance testing of newly installed photovoltaic systems,1.2.2 reporting of dc or ac system pe
4、rformance, and1.2.3 monitoring of photovoltaic system performance.1.3 This test method should not be used for:1.3.1 testing of individual photovoltaic modules for comparison to nameplate power ratings,1.3.2 testing of individual photovoltaic modules or systems for comparison to other photovoltaic mo
5、dules or systems,1.3.3 testing of photovoltaic systems for the purpose of comparing the performance of photovoltaic systems located in differentplaces.1.4 In this test method, photovoltaic system power is reported with respect to a set of reporting conditions (RC) including: solarirradiance in the p
6、lane of the modules, ambient temperature, and wind speed (see Section 6). Measurements under a variety ofreporting conditions are allowed to facilitate testing and comparison of results.1.5 This test method assumes that the solar cell temperature is directly influenced by ambient temperature and win
7、d speed; ifnot the regression results may be less meaningful.1.6 The capacity measured according to this test method should not be used to make representations about the energy generationcapabilities of the system.1.7 This test method is not applicable to concentrator photovoltaic systems; as an alt
8、ernative, Test Method E2527 should beconsidered for such systems.1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It
9、 is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D6176 Practice for Measuring Surface Atmospheric Temperature with Electrical Resist
10、ance Temperature SensorsE772 Terminology of Solar Energy ConversionE824 Test Method for Transfer of Calibration From Reference to Field RadiometersE927 Specification for Solar Simulation for Photovoltaic TestingE948 Test Method for Electrical Performance of Photovoltaic Cells Using Reference Cells U
11、nder Simulated Sunlight1 This test method is under the jurisdiction of ASTM Committee E44 on Solar, Geothermal and Other Alternative Energy Sources, and is the direct responsibility ofSubcommittee E44.09 on Photovoltaic Electric Power Conversion.Current edition approved Nov. 1, 2011Sept. 1, 2013. Pu
12、blished December 2011September 2013. Originally approved in 2011. Last previous edition approved in 2011 asE2848-111. DOI: 10.1520/E2848-11E01.10.1520/E2848-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of
13、ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically
14、 possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C70
15、0, West Conshohocken, PA 19428-2959. United States1E973 Test Method for Determination of the Spectral Mismatch Parameter Between a Photovoltaic Device and a PhotovoltaicReference CellE1036 Test Methods for Electrical Performance of Nonconcentrator Terrestrial Photovoltaic Modules and Arrays UsingRef
16、erence CellsE1040 Specification for Physical Characteristics of Nonconcentrator Terrestrial Photovoltaic Reference CellsE1125 Test Method for Calibration of Primary Non-Concentrator Terrestrial Photovoltaic Reference Cells Using a TabularSpectrumE1362 Test Method for Calibration of Non-Concentrator
17、Photovoltaic Secondary Reference CellsE2527 Test Method for Electrical Performance of Concentrator Terrestrial Photovoltaic Modules and Systems Under NaturalSunlightG138 Test Method for Calibration of a Spectroradiometer Using a Standard Source of IrradianceG167 Test Method for Calibration of a Pyra
18、nometer Using a PyrheliometerG173 Tables for Reference Solar Spectral Irradiances: Direct Normal and Hemispherical on 37 Tilted SurfaceG183 Practice for Field Use of Pyranometers, Pyrheliometers and UV Radiometers2.2 IEEE Standards:IEEE 1526-2003 Recommended Practice for Testing the Performance of S
19、tand-Alone Photovoltaic SystemsIEEE 1547-2003 Standard for Interconnecting Distributed Resources with Electric Power Systems2.3 International Standards Organization Standards:ISO/IEC Guide 98-1:2009 Uncertainty of measurementPart 1: Introduction to the expression of uncertainty in measurementISO/IEC
20、 Guide 98-3:2008 Uncertainty of measurementPart 3: Guide to the expression of uncertainty in measurement(GUM:1995)2.4 World Meteorological Organization (WMO) Standard:WMO-No. 8 Guide to Meteorological Instruments and Methods of Observation, Seventh Ed., 20083. Terminology3.1 DefinitionsDefinitions o
21、f terms used in this test method may be found in Terminology E772, IEEE 1547-2003, andISO/IEC Guide 98-1:2009 and ISO/IEC Guide 98-3:2008.3.2 Definitions of Terms Specific to This Standard:3.2.1 averaging interval, nthe time interval over which data isare averaged to obtain one data point. The perfo
22、rmance test isperformed using uses these averaged data.3.2.2 data collection period, nthe period of time defined by the user of this test method during which system output power,irradiance, ambient temperature, and wind speed are measured and recorded for the purposes of a single regression analysis
23、.3.2.3 plane-of-array irradiance, POA, nsee solar irradiance, hemispherical in Tables G173.3.2.4 reporting conditions, RC, nan agreed-upon set of conditions including the plane-of-array irradiance, ambienttemperature, and wind speed conditions to which photovoltaic system performance are reported. T
24、he reporting conditions mustalso state the type of radiometer used to measure the plane-of-array irradiance. In the case where this test method is to be usedfor acceptance testing of a photovoltaic system or reporting of photovoltaic system performance for contractual purposes, RC RC,or the method t
25、hat will be used to derive the RC, shall be stated in the contract or agreed upon in writing by the parties to theacceptance testing and reporting prior to the start of the test.3.2.5 sampling interval, nthe elapsed time between scans of the sensors used to measure power, irradiance, ambienttemperat
26、ure and wind speed. Individual data points used for the performance test are averages of the values recorded in these scans.There are multiple sampling intervals in each averaging interval.3.2.6 utility grid, nsee electric power system in IEEE 1547-2003.3.3 Symbols: The following symbols and units a
27、re used in this test method:3.3.1 reference cell ISC temperature coefficient, C13.3.2 a1, a2, a3, a4linear regression coefficients, arbitrary3.3.3 a, b, c, dspectral mismatch factor calibration constants, arbitrary3.3.4 Creference cell calibration constant, Am2W13.3.5 Coreference cell calibration co
28、nstant at SRC, Am2W13.3.6 Eplane-of-array irradiance, W/m23.3.7 EoRC rating irradiance (plane-of-array),irradiance at SRC, plane-of-array, W/m23.3.8 PEo()photovoltaic system power, ac or reference spectral irradiance distribution, Wm2 dc, nm1 W3.3.9 ERCRC rating irradiance, plane-of-array, W/m23.3.1
29、0 PEoRC()photovoltaic system powerspectral irradiance distribution at RC, ac Wm2 or nm1 dc, WE2848 1323.3.11 TEaT()ambient temperature, Cspectral irradiance distribution, test light source, Wm2 nm13.3.12 TFoRC rating temperature, Cfractional error in short-circuit current, dimensionless3.3.13 vISCwi
30、nd speed, m/sshort-circuit current, A3.3.14 vMoRC rating wind speed, m/sspectral mismatch factor, dimensionless3.3.15 pp-value, a dimensionless quantity used to determine the significance of an individual regression coefficient to theoverall rating result3.3.16 Pphotovoltaic system power, ac or dc,
31、W3.3.17 PRCphotovoltaic system power at RC, ac or dc, W3.3.18 RCreporting conditions3.3.19 RR()reference cell spectral responsivity, A/W3.3.20 RT()test device spectral responsivity, A/W3.3.21 SRCstandard reporting conditions3.3.22 SEstandard error, W3.3.23 Taambient temperature, C3.3.24 TRCRC rating
32、 temperature, C3.3.25 U95expanded uncertainty with a 95 % coverage probability of photovoltaic system power at RC, W3.3.26 wavelength, nm3.3.27 vwind speed, m/s3.3.28 vRCRC rating wind speed, m/s4. Summary of Test Method4.1 Photovoltaic system power, solar irradiance, ambient temperature, and wind s
33、peed data are collected over a defined periodof time using a data acquisition system.4.2 Multiple linear regression is then used to fit the collected data to the performance equation (Eq 1) and thereby calculate theregression coefficients a1,a2,a3, and a4.P 5Ea11a2E1a3Ta1a4v! (1)P 5Ea11a2 E1a3 Ta1a4
34、 v! (1)4.3 Substitution of the RC values Eo,To, and vo into Eq 1 then gives the ac or dc power at the Reporting Conditions.reportingconditions.Po 5Eoa11a2Eo1a3To1a4vo! (2)PRC 5ERCa11a2 ERC1a3 TRC1a4 vRC! (2)4.4 The collected input data and the performance at the reporting conditions are then reporte
35、d.5. Significance and Use5.1 Because there are a number of choices in this test method that depend on different applications and system configurations,it is the responsibility of the user of this test method to specify the details and protocol of an individual system power measurementprior to the be
36、ginning of a measurement.5.2 Unlike device-level measurements that report performance at a fixed device temperature of 25C, such as Test MethodsE1036, this test method uses regression to a reference ambient air temperature.5.2.1 System power values calculated using this test method are therefore muc
37、h more indicative of the power a system actuallyproduces compared with reporting performance at a relatively cold device temperature such as 25C.5.2.2 Using ambient temperature reduces the complexity of the data acquisition and analysis by avoiding the issues associatedwith defining and measuring th
38、e device temperature of an entire photovoltaic system.5.2.3 The user of this test method must select the time period over which system data are collected, and the averaging intervalfor the data collection within the constraints of 8.3.5.2.4 It is assumed that the system performance does not degrade
39、or change during the data collection time period. Thisassumption influences the selection of the data collection period because system performance can have seasonal variations.5.3 The irradiance shall be measured in the plane of the modules under test. If multiple planes exist (particularly in the c
40、aseof rolling terrain), then the plane or planes in which irradiance measurement will occur must be reported with the test results. Inthe case where this test method is to be used for acceptance testing of a photovoltaic system or reporting of photovoltaic systemE2848 133performance for contractual
41、purposes, the plane or planes in which irradiance measurement will occur must be agreed upon by theparties to the test prior to the start of the test.NOTE 1In general, the irradiance measurement should occur in the plane in which the majority of modules are oriented. Placing the measurementdevice in
42、 a plane with a larger tilt than the majority will cause apparent under-performance in the winter and over-performance in the summer.5.3.1 The linear regression results will be most reliable when the measured irradiance, ambient temperature, and wind speeddata during the data collection period are d
43、istributed around the reporting conditions. When this is not the case, the reported powerwill be an extrapolation to the reporting conditions.5.4 Accumulation of dirt (soiling) on the photovoltaic modules can have a significant impact on the system rating. The user ofthis test may want to eliminate
44、or quantify the level of soiling on the modules prior to conducting the test.5.5 Repeated regression calculations on the same system to the same RC and using the same type of irradiance measurementdevice over successive data collection periods can be used to monitor performance changes as a function
45、 of time.5.6 Capacity determinations are power measurements and are adequate to demonstrate system completeness. However, a singlecapacity measurement does not provide sufficient information to project the energy generation potential of the system over time.Factors that may affect energy generation
46、over time include: module power degradation, inverter clipping and overloading,shading, backtracking, extreme orientations, and filtering criteria.6. Reporting Conditions6.1 The user of this test method shall select an appropriate RC prior to the start of the test. appropriate RC. In the case wheret
47、his test method is to be used for acceptance testing of a photovoltaic system or reporting of photovoltaic system performance forcontractual purposes, the RC RC, or the method that will be used to derive the RC, must be agreed upon by the parties to the testprior to the start of the test.6.1.1 Repor
48、ting conditions may be selected either on the basis of expected conditions or actual conditions during the datacollection period. Choose RC irradiance and ambient air temperature values that are representative of the in-planePOA irradianceand ambient air temperature expected for the system location
49、for a clear day in the data collection period. Irradiance conditionsWhen the selection is based on expected conditions, irradiance can be evaluated based on from a year-long hourly dataset ofprojected POAvalues calculated from historical data measured directly on the system site or at a nearby site.Ambient temperaturescan be evaluated by a review of historical data from the site or a nearby location. Reference ConditionsReporting conditions shouldbe chosen such that the system is not subject to
