1、Designation: E2848 111Standard 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 rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEAnnex A1, Eq A1.5 was corrected editorially in September 2012.1. Scope1.1 This test method provides measurement and analysisprocedure
3、s for determining the capacity of a specific photovol-taic system built 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,
4、 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 com-parison to nameplate power ratings,1.3.2 testing of individual photovoltaic modules or systemsfor comparison to other photovoltaic modules or s
5、ystems,1.3.3 testing of photovoltaic systems for the purpose ofcomparing 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
6、modules, ambienttemperature, and wind speed (see Section 6). Measurementsunder 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
7、the regression results may be less meaningful.1.6 This test method is 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 inclu
8、ded 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 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to
9、 use.2. Referenced Documents2.1 ASTM Standards:2D6176 Practice for Measuring 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 f
10、or Solar Simulation for PhotovoltaicTestingE948 Test Method for Electrical Performance of Photovol-taic Cells Using Reference Cells Under Simulated Sun-lightE973 Test Method for Determination of the Spectral Mis-match Parameter Between a Photovoltaic Device and aPhotovoltaic Reference CellE1036 Test
11、 Methods for Electrical Performance of Noncon-centrator Terrestrial Photovoltaic Modules and ArraysUsing Reference CellsE1040 Specification for Physical Characteristics of Noncon-centrator Terrestrial Photovoltaic Reference CellsE1125 Test Method for Calibration of Primary Non-Concentrator Terrestri
12、al Photovoltaic Reference Cells Us-ing a Tabular SpectrumE1362 Test Method for Calibration of Non-ConcentratorPhotovoltaic Secondary Reference CellsE2527 Test Method for Electrical Performance of Concen-trator Terrestrial Photovoltaic Modules and Systems Un-der Natural SunlightG138 Test Method for C
13、alibration of a SpectroradiometerUsing a Standard Source of Irradiance1This 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 ed
14、ition approved Nov. 1, 2011. Published December 2011. DOI:10.1520/E2848-11E01.2For 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 on
15、the ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1G167 Test Method for Calibration of a Pyranometer Using aPyrheliometerG173 Tables for Reference Solar Spectral Irradiances: DirectNormal and Hemispherical on 37 Tilted S
16、urfaceG183 Practice for Field Use of Pyranometers, Pyrheliom-eters and UV Radiometers2.2 IEEE Standards:IEEE 1526-2003 Recommended Practice for Testing thePerformance of Stand-Alone Photovoltaic SystemsIEEE 1547-2003 Standard for Interconnecting DistributedResources with Electric Power Systems2.3 In
17、ternational Standards Organization Standards:ISO/IEC Guide 98-1:2009 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 Meteo
18、rological Organization (WMO) Standard:WMO-No. 8 Guide to Meteorological 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-
19、3:2008.3.2 Definitions of Terms Specific to This Standard:3.2.1 averaging 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 met
20、hod during which system outputpower, irradiance, ambient temperature, and wind speed aremeasured and recorded for the purposes of a single regressionanalysis.3.2.3 plane-of-array irradiance, POA, nsee solarirradiance, hemispherical in Tables G173.3.2.4 reporting conditions, RC, nan agreed-upon set o
21、fconditions including the plane-of-array irradiance, ambienttemperature, 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 ist
22、o be used for acceptance testing of a photovoltaic system orreporting 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,
23、nthe elapsed time between scansof the sensors used to measure power, 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 gri
24、d, nsee electric power system in IEEE1547-2003.3.3 Symbols: The following 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
25、 dc, W3.3.5 Taambient temperature, C3.3.6 ToRC rating temperature, 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
26、U95expanded uncertainty with a 95 % coverageprobability of photovoltaic 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 linea
27、r regression is then used to fit the collecteddata to the performance equation (Eq 1) and thereby calculatethe regression coefficients a1, a2, a3, and a4.P 5 Ea11a2E1a3Ta1a4v! (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 Eo
28、a11a2Eo1a3To1a4vo! (2)4.4 The collected input data and 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
29、 of this testmethod to specify the details and protocol 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
30、 a referenceambient air temperature.5.2.1 System power 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
31、complexity ofthe data acquisition and analysis by avoiding 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 dat
32、a collection within the constraints of 8.3.E2848 11125.2.4 It is 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
33、 irradiance shall be measured in the plane of themodules under test. 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 forac
34、ceptance testing of a photovoltaic system or reporting ofphotovoltaic 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.NOTE 1In general, the irradiance measurement sh
35、ould occur in theplane in which the majority of modules 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 m
36、easured irradiance, ambient temperature, and windspeed data 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-ul
37、es can have a significant impact on the system rating. Theuser 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 devic
38、e over successive data collection periods can beused to 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
39、photovoltaicsystem or reporting of photovoltaic system performance 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 a
40、ir temperature expected for the system location for aclear 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
41、can be evaluated by a review of historical datafrom the 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 o
42、f installed DC capacity to AC inverter capacity maybe such 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 irradian
43、ce modeling toolsthat can be used to develop an hourly year-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 Condi
44、tions”, or “PTC”, have been used commonly. PTC conditionsuse 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 Temper
45、ature (NOCT) of an individualsolar cell inside a module (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 airtemp
46、erature shall have a resolution of at least 0.1C, and shallhave 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 se
47、nsor shall be mounted with an aspirated radiation shieldas 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) wit
48、h the photovoltaic system under test and shall beconnected to a data acquisition system. The equipment shouldbe mounted in a location that minimizes, and ideallyeliminates, shading of and reflections on the instrument.7.2.1 A calibrated hemispherical pyranometer (instrumentswith fields-of-view appro
49、aching 180, see Terminology E772)is the most common choice 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 lo
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1