1、Designation: E2848 11Standard 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 last revi
2、sion. 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 provides measurement and analysisprocedures for determining the capacity of a specific photovol-taic system bu
3、ilt in a particular place and in operation undernatural sunlight.1.2 This test method is used for the following purposes:1.2.1 acceptance testing of newly installed photovoltaicsystems,1.2.2 reporting of dc or ac system performance, and1.2.3 monitoring of photovoltaic system performance.1.3 This tes
4、t method should not be used for:1.3.1 testing of individual photovoltaic modules for com-parison to nameplate power ratings,1.3.2 testing of individual photovoltaic modules or systemsfor comparison to other photovoltaic modules or systems,1.3.3 testing of photovoltaic systems for the purpose ofcompa
5、ring the performance of photovoltaic systems located indifferent places.1.4 In this test method, photovoltaic system power isreported with respect to a set of reporting conditions (RC)including: solar irradiance in the plane of the modules, ambienttemperature, and wind speed (see Section 6). Measure
6、mentsunder a variety of reporting conditions are allowed to facilitatetesting and comparison of results.1.5 This test method assumes that the solar cell temperatureis directly influenced by ambient temperature and wind speed;if not the regression results may be less meaningful.1.6 This test method i
7、s not applicable to concentratorphotovoltaic systems; as an alternative, Test Method E2527should be considered for such systems.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 al
8、l 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:2D6176 Practice for M
9、easuring Surface Atmospheric Tem-perature with Electrical Resistance Temperature SensorsE772 Terminology of Solar Energy ConversionE824 Test Method for Transfer of Calibration From Refer-ence to Field RadiometersE927 Specification for Solar Simulation for PhotovoltaicTestingE948 Test Method for Elec
10、trical 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 CellE1036 Test Methods for Electrical Performance of Noncon-centrator Terrestrial P
11、hotovoltaic Modules and ArraysUsing Reference CellsE1040 Specification for Physical Characteristics of Non-concentrator Terrestrial Photovoltaic Reference CellsE1125 Test Method for Calibration of Primary Non-Concentrator Terrestrial Photovoltaic Reference Cells Us-ing a Tabular SpectrumE1362 Test M
12、ethod for Calibration of Non-ConcentratorPhotovoltaic Secondary Reference CellsE2527 Test Method for Electrical Performance of Concen-trator Terrestrial Photovoltaic Modules and Systems UnderNatural SunlightG138 Test Method for Calibration of a SpectroradiometerUsing a Standard Source of IrradianceG
13、167 Test Method for Calibration of a Pyranometer Usinga PyrheliometerG173 Tables for Reference Solar Spectral Irradiances: Di-rect Normal and Hemispherical on 37 Tilted SurfaceG183 Practice for Field Use of Pyranometers, Pyrheliom-eters and UV Radiometers2.2 IEEE Standards:IEEE 1526-2003 Recommended
14、 Practice for Testing thePerformance of Stand-Alone Photovoltaic Systems1This test method is under the jurisdiction of ASTM Committee E44 on Solar,Geothermal and Other Alternative Energy Sources , and is the direct responsibilityof Subcommittee E44.09 on Photovoltaic Electric Power Conversion.Curren
15、t edition approved Nov. 1, 2011. Published December 2011. DOI:10.1520/E2848-11.2For 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 o
16、nthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.IEEE 1547-2003 Standard for Interconnecting DistributedResources with Electric Power Systems2.3 International Standards Organization Standards:ISO/IEC Guide 98-1:2009
17、Uncertainty of measurementPart 1: Introduction to the expression of uncertainty inmeasurementISO/IEC Guide 98-3:2008 Uncertainty of measurementPart 3: Guide to the expression of uncertainty in measure-ment (GUM:1995)2.4 World Meteorological Organization (WMO) Standard:WMO-No. 8 Guide to Meteorologic
18、al Instruments andMethods of Observation, Seventh Ed., 20083. Terminology3.1 DefinitionsDefinitions of terms used in this testmethod may be found in Terminology E772, IEEE 1547-2003,and ISO/IEC Guide 98-1:2009 and ISO/IEC Guide 98-3:2008.3.2 Definitions of Terms Specific to This Standard:3.2.1 avera
19、ging interval, nthe time interval over whichdata is averaged to obtain one data point. The performance testis performed using these averaged data.3.2.2 data collection period, nthe period of time definedby the user of this test method during which system outputpower, irradiance, ambient temperature,
20、 and wind speed aremeasured and recorded for the purposes of a single regressionanalysis.3.2.3 plane-of-array irradiance, POA, nsee solar irradi-ance, hemispherical in Tables G173.3.2.4 reporting conditions, RC, nan agreed-upon set ofconditions including the plane-of-array irradiance, ambienttempera
21、ture, and wind speed conditions to which photovoltaicsystem performance are reported. The reporting conditionsmust also state the type of radiometer used to measure theplane-of-array irradiance. In the case where this test method isto be used for acceptance testing of a photovoltaic system orreporti
22、ng of photovoltaic system performance for contractualpurposes, RC shall be stated in the contract or agreed upon inwriting by the parties to the acceptance testing and reportingprior to the start of the test.3.2.5 sampling interval, nthe elapsed time between scansof the sensors used to measure power
23、, irradiance, ambienttemperature and wind speed. Individual data points used for theperformance test are averages of the values recorded in thesescans. There are multiple sampling intervals in each averaginginterval.3.2.6 utility grid, nsee electric power system inIEEE 1547-2003.3.3 Symbols: The fol
24、lowing symbols and units are used inthis test method:3.3.1 Eplane-of-array irradiance, W/m23.3.2 EoRC rating irradiance (plane-of-array), W/m23.3.3 Pphotovoltaic system power, ac or dc, W3.3.4 Pophotovoltaic system power at RC, ac or dc, W3.3.5 Taambient temperature, C3.3.6 ToRC rating temperature,
25、C3.3.7 vwind speed, m/s3.3.8 voRC rating wind speed, m/s3.3.9 pp-value, a dimensionless quantity used to deter-mine the significance of an individual regression coefficient tothe overall rating result3.3.10 SEstandard error, W3.3.11 U95expanded uncertainty with a 95 % coverageprobability of photovol
26、taic system power at RC, W4. Summary of Test Method4.1 Photovoltaic system power, solar irradiance, ambienttemperature, and wind speed data are collected over a definedperiod of time using a data acquisition system.4.2 Multiple linear regression is then used to fit the collecteddata to the performan
27、ce equation (Eq 1) and thereby calculatethe regression coefficients a1, a2, a3, and a4.P 5 Ea11 a2 E 1 a3 Ta1 a4v! (1)4.3 Substitution of the RC values Eo, To, and vointo Eq 1then gives the ac or dc power at the Reporting Conditions.Po5 Eoa11 a2 Eo1 a3 To1 a4 vo! (2)4.4 The collected input data and
28、the performance at thereporting conditions are then reported.5. Significance and Use5.1 Because there are a number of choices in this testmethod that depend on different applications and systemconfigurations, it is the responsibility of the user of this testmethod to specify the details and protocol
29、 of an individualsystem power measurement prior to the beginning of a mea-surement.5.2 Unlike device-level measurements that report perfor-mance at a fixed device temperature of 25C, such as TestMethods E1036, this test method uses regression to a referenceambient air temperature.5.2.1 System power
30、values calculated using this test methodare therefore much more indicative of the power a systemactually produces compared with reporting performance at arelatively cold device temperature such as 25C.5.2.2 Using ambient temperature reduces the complexity ofthe data acquisition and analysis by avoid
31、ing the issuesassociated with defining and measuring the device temperatureof an entire photovoltaic system.5.2.3 The user of this test method must select the timeperiod over which system data are collected, and the averaginginterval for the data collection within the constraints of 8.3.5.2.4 It is
32、assumed that the system performance does notdegrade or change during the data collection time period. Thisassumption influences the selection of the data collectionperiod because system performance can have seasonal varia-tions.5.3 The irradiance shall be measured in the plane of themodules under te
33、st. If multiple planes exist (particularly in thecase of rolling terrain), then the plane or planes in whichirradiance measurement will occur must be reported with thetest results. In the case where this test method is to be used foracceptance testing of a photovoltaic system or reporting ofphotovol
34、taic system performance for contractual purposes, theplane or planes in which irradiance measurement will occurmust be agreed upon by the parties to the test prior to the startof the test.E2848 112NOTE 1In general, the irradiance measurement should occur in theplane in which the majority of modules
35、are oriented. Placing themeasurement device in a plane with a larger tilt than the majority willcause apparent under-performance in the winter and over-performance inthe summer.5.3.1 The linear regression results will be most reliablewhen the measured irradiance, ambient temperature, and windspeed d
36、ata during the data collection period are distributedaround the reporting conditions. When this is not the case, thereported power will be an extrapolation to the reportingconditions.5.4 Accumulation of dirt (soiling) on the photovoltaic mod-ules can have a significant impact on the system rating. T
37、heuser of this test may want to eliminate or quantify the level ofsoiling on the modules prior to conducting the test.5.5 Repeated regression calculations on the same system tothe same RC and using the same type of irradiance measure-ment device over successive data collection periods can beused to
38、monitor performance changes as a function of time.6. Reporting Conditions6.1 The user of this test method shall select an appropriateRC prior to the start of the test. In the case where this testmethod is to be used for acceptance testing of a photovoltaicsystem or reporting of photovoltaic system p
39、erformance forcontractual purposes, the RC must be agreed upon by theparties to the test prior to the start of the test.6.1.1 Choose RC irradiance and ambient air temperaturevalues that are representative of the in-plane irradiance andambient air temperature expected for the system location for acle
40、ar day in the data collection period. Irradiance conditionscan be evaluated based on a year-long hourly dataset ofprojected POA values calculated from historical data measureddirectly on the system site or at a nearby site. Ambienttemperatures can be evaluated by a review of historical datafrom the
41、site or a nearby location. Reference Conditions shouldbe chosen such that the system is not subject to frequentshading, inverter clipping or other non-linear operation at oraround the RC. For instance, in larger photovoltaic systems,the ratio of installed DC capacity to AC inverter capacity maybe su
42、ch that the inverter limits the production of the modulesunder certain conditions. If this is the case, care should betaken to choose a reference within the normal operating rangeof the inverters.NOTE 2There are many publicly-available irradiance modeling toolsthat can be used to develop an hourly y
43、ear-long dataset for POAirradianceat a project site based on historical global horizontal irradiance data or, ifavailable, from data measured directly at the project site.NOTE 3Historically, a specific case of RC known as “PerformanceTest Conditions”, or “PTC”, have been used commonly. PTC condition
44、suse plane-of-array irradiance equal to 1000 W/m2, ambient temperatureequal to 20C, and wind speed equal to 1 m/s. The PTC parameters werebased on the Nominal Terrestrial Environment (NTE) conditions thatdefine the Nominal Operating Cell Temperature (NOCT) of an individualsolar cell inside a module
45、(see Annex A1 in Test Methods E1036).However, NTE differs from PTC in that it specifies a lower irradiance of800 W/m2.7. Apparatus7.1 Ambient Air Temperature Measurement EquipmentThe instrument or instruments used to measure the ambient airtemperature shall have a resolution of at least 0.1C, and sh
46、allhave a total error of less than 61C of reading. The sensorshould be mounted in the immediate vicinity of the photovol-taic system under test, but should not be so close to themodules as to be in the thermal boundary layer of the array.The sensor shall be mounted with an aspirated radiation shield
47、as defined in 3.2.3 of Practice D6176. Practice D6176 containsadditional guidance for ambient air temperature measurements.7.2 Irradiance Measurement EquipmentThe irradiancemeasurement equipment shall be mounted coplanar (to within1 degree) with the photovoltaic system under test and shall beconnect
48、ed to a data acquisition system. The equipment shouldbe mounted in a location that minimizes, and ideally elimi-nates, shading of and reflections on the instrument.7.2.1 A calibrated hemispherical pyranometer (instrumentswith fields-of-view approaching 180, see Terminology E772)is the most common ch
49、oice for measurement of the incidentsolar irradiance. Pyranometers used in this test shall becalibrated using Test Method E824 or Test Method G167. TestMethod E E824 is a transfer calibration from a reference to afield pyranometer, while Test Method G167 involves calibra-tion against either of two types of narrow field-of-viewpyrheliometers. The uncertainty of the pyranometer calibrationis a function of the calibration method, with the Type Icalibration in Test Method G167 giving the lowest uncertainty.7.2.2 Pyranometers are sensitive to both
