1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationPhotovoltaic devicesPart 5: Determination of the equivalent cell temperature (ECT) of photovoltaic (PV) devices by the open-circuit voltage methodBS EN 60904-5:2011National forew
2、ordThis British Standard is the UK implementation of EN 60904-5:2011. It isidentical to IEC 60904-5:2011. It supersedes BS EN 60904-5:1996 which iswithdrawn.The UK participation in its preparation was entrusted to Technical CommitteeGEL/82, Photovoltaic Energy Systems.A list of organizations represe
3、nted on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application. BSI 2011ISBN 978 0 580 70929 6ICS 27.160Compliance with a British Standard cannot confer immuni
4、ty fromlegal obligations.This British Standard was published under the authority of the StandardsPolicy and Strategy Committee on 30 June 2011.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS EN 60904-5:2011EUROPEAN STANDARD EN 60904-5 NORME EUROPENNE EUROPISCHE NORM
5、April 2011 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2011 CENELEC - All rights of exploitation in any form and by any means re
6、served worldwide for CENELEC members. Ref. No. EN 60904-5:2011 E ICS 27.160 Supersedes EN 60904-5:1995English version Photovoltaic devices - Part 5: Determination of the equivalent cell temperature (ECT) of photovoltaic (PV) devices by the open-circuit voltage method (IEC 60904-5:2011) Dispositifs p
7、hotovoltaques - Partie 5: Dtermination de la temprature de cellule quivalente (ECT) des dispositifs photovoltaques (PV) par la mthode de la tension en circuit ouvert (CEI 60904-5:2011) Photovoltaische Einrichtungen - Teil 5: Bestimmung der gleichwertigen Zellentemperatur von photovoltaischen (PV) Be
8、triebsmitteln nach dem Leerlaufspannungs-Verfahren (IEC 60904-5:2011) This European Standard was approved by CENELEC on 2011-03-24. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national
9、standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any
10、 other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, th
11、e Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 60904-5:2011EN 60904-5:2011 -
12、 2 - Foreword The text of document 82/595/CDV, future edition 2 of IEC 60904-5, prepared by IEC TC 82, Solar photovoltaic energy systems, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60904-5 on 2011-03-24. This European Standard supersedes EN 60904-5:1995. The mai
13、n technical changes with regard to EN 60904-5:1995 are as follows: added and updated normative references; added reporting section; added method on how to extract the input parameters; rewritten method on how to calculate ECT; reworked formulae to be in line with EN 60891. Attention is drawn to the
14、possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication
15、of an identical national standard or by endorsement (dop) 2011-12-24 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2014-03-24 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 60904-5:2011 was approved
16、 by CENELEC as a European Standard without any modification. _ BS EN 60904-5:2011- 3 - EN 60904-5:2011 Annex ZA (normative) Normative references to international publications with their corresponding European publications The following referenced documents are indispensable for the application of th
17、is document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applie
18、s. Publication Year Title EN/HD Year IEC 60891 - Photovoltaic devices - Procedures for temperature and irradiance corrections to measured I-V characteristics EN 60891 - IEC 60904-1 - Photovoltaic devices - Part 1: Measurement of photovoltaic current-voltage characteristics EN 60904-1 - IEC 60904-2 -
19、 Photovoltaic devices - Part 2: Requirements for reference solar devices EN 60904-2 - IEC 60904-7 - Photovoltaic devices - Part 7: Computation of the spectral mismatch correction for measurements of photovoltaic devices EN 60904-7 - IEC 60904-10 - Photovoltaic devices - Part 10: Methods of linearity
20、 measurement EN 60904-10 - IEC 61215 - Crystalline silicon terrestrial photovoltaic (PV) modules - Design qualification and type approval EN 61215 - IEC 61829 - Crystalline silicon photovoltaic (PV) array - On-site measurement of I-V characteristics EN 61829 - ISO/IEC 17025 - General requirements fo
21、r the competence of testing and calibration laboratories EN ISO/IEC 17025 - BS EN 60904-5:2011 2 60904-5 IEC:2011 CONTENTS INTRODUCTION . 5 1 Scope and object 6 2 Normative references . 6 3 Measurement principle and requirements . 6 3.1 Principle 6 3.2 General measurement requirements 7 4 Apparatus
22、. 7 5 Determination of required input parameters 7 6 Procedure 8 6.1 General . 8 6.2 Operating in a controlled environment . 8 6.3 Taking measurements under arbitrary irradiance conditions 8 7 Calculation of equivalent cell temperature 8 8 Test report 9 BS EN 60904-5:201160904-5 IEC:2011 5 INTRODUCT
23、ION When temperature sensors, such as thermocouples, are used to determine the cell temperature of PV devices under natural or simulated steady-state irradiance, two main problems arise. First, a considerable spread of temperature can be observed over the area of the module. Second, as the solar cel
24、ls are usually not accessible, sensors are attached to the back of the module and the measured temperature thus is influenced by the thermal conductivity of the encapsulant and back materials. These problems are aggravated when determining the equivalent cell temperature for on-site measurements of
25、array performance where all cells have slightly different temperatures and one cannot easily determine the average cell temperature. The equivalent cell temperature (ECT) is the average temperature at the electronic junctions of the device (cells, modules, arrays of one type of module) which equates
26、 to the current operating temperature if the entire device were operating uniformly at this junction temperature. BS EN 60904-5:2011 6 60904-5 IEC:2011 PHOTOVOLTAIC DEVICES Part 5: Determination of the equivalent cell temperature (ECT) of photovoltaic (PV) devices by the open-circuit voltage method
27、1 Scope and object This part of IEC 60904 describes the preferred method for determining the equivalent cell temperature (ECT) of PV devices (cells, modules and arrays of one type of module), for the purposes of comparing their thermal characteristics, determining NOCT (nominal operating cell temper
28、ature) and translating measured I-V characteristics to other temperatures. This standard applies to linear devices with logarithmic VOCdependence on irradiance and in stable conditions. It may be used for all technologies but one has to verify that there is no preconditioning effect influencing the
29、measurement. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60891, Ph
30、otovoltaic devices Procedures for temperature and irradiance corrections to measured I-V characteristics IEC 60904-1, Photovoltaic devices Part 1: Measurement of photovoltaic current-voltage characteristics IEC 60904-2, Photovoltaic devices Part 2: Requirements for reference solar devices IEC 60904-
31、7, Photovoltaic devices Part 7: Computation of the spectral mismatch correction for measurements of photovoltaic devices IEC 60904-10, Photovoltaic devices Part 10: Methods of linearity measurement IEC 61215, Crystalline silicon terrestrial photovoltaic (PV) modules Design qualification and type app
32、roval IEC 61829, Crystalline silicon photovoltaic (PV) array On-site measurement of I-V characteristics ISO/IEC 17025, General requirements for competence of testing and calibration laboratories 3 Measurement principle and requirements 3.1 Principle The method described below is based on the fact th
33、at the open-circuit voltage (VOC) of a solar cell changes with temperature in a predictable fashion. If the open-circuit voltage of the device at standard test conditions is known, together with its temperature coefficient, the BS EN 60904-5:201160904-5 IEC:2011 7 equivalent temperature of all the c
34、ells in the device can be determined. The open-circuit voltage is also slightly affected by the irradiance, so an additional correction may be required as outlined in IEC 60891. Experience shows that the equivalent cell temperature can be determined more precisely by the method described here than b
35、y any alternative technique. However, as the temperature coefficient drops rapidly at irradiances below 200 W/m2, this method should only be used at irradiances above this threshold. 3.2 General measurement requirements a) The device under test needs to match the following criteria: 1) The variation
36、 of VOCneeds to be linear as defined in IEC 60904-10 with respect to temperature. 2) The variation of VOCneeds to follow a logarithmic dependence with irradiance. 3) It needs to have an ohmic series resistance as otherwise there will be different ECT-coefficients for different temperature regions. 4
37、) The shunt resistances of the device need to be reasonably high, as for the majority of commercially available devices, as otherwise there will be different ECT-coefficients for different temperature regions. b) The irradiance measurements shall be made using a PV reference device packaged and cali
38、brated in conformance with IEC 60904-2 or a pyranometer. The PV reference device shall either be spectrally matched to the test specimen, or a spectral mismatch correction shall be performed in conformance with IEC 60904-7. The reference device shall be linear in short-circuit current as defined in
39、IEC 60904-10 over the irradiance range of interest. In accordance with IEC 60904-2, to be considered spectrally matched, a reference device shall be constructed using the same cell technology and encapsulation package as the test device. Otherwise the spectral mismatch will have to be reported. NOTE
40、 Some devices might have a significant spectral dependency in the open-circuit voltage. In such a case, a spectroradiometer would be needed to ensure stable incident spectrum. c) The active surface of the specimen shall be coplanar within 2 of the active surface of the reference device. d) Voltages
41、shall be measured to an accuracy of 0,2 % of the open-circuit voltage using independent leads from the terminals of the specimen and keeping them as short as possible. The measurement ranges of the data acquisition should be carefully chosen. If the test specimen is a module, the 4-wire connection s
42、hould start at the terminals or connectors. If the test specimen is a cell, the 4-wire connection should start at the bus bars. 4 Apparatus In addition to the general measurement requirements of Clause 3 the following equipment is required to perform I-V characteristic measurements: a) A PV referenc
43、e device that meets the conditions stated in 3 a). b) Equipment to measure the open-circuit voltage to a precision better than 0,2 %. c) Equipment to measure temperature to a precision 1 K. 5 Determination of required input parameters The procedure requires a number of input parameters. These are: T
44、emperature coefficient of the open circuit voltage, . This shall be determined from cell or module measurements of representative samples in accordance with IEC 60891. Open-circuit voltage (VOC1) at a reference condition (G1, T1) in accordance with IEC 60904-1 for a cell or module or in accordance w
45、ith IEC 61829 for a PV array. The BS EN 60904-5:2011 8 60904-5 IEC:2011 reference condition is often chosen to be the standard test conditions as defined in IEC 61215, i.e. GSTC= 1 000 W/m2and TSTC= 25 C. The procedure requires a constant, a , which is also interpreted as the thermal diode voltage.
46、The determination of this requires the measurement of the open-circuit voltage at two different irradiance levels G3and G4, one of which may be the point G1,T1. 6 Procedure 6.1 General The procedure can be carried out either in a controlled environment or by taking measurements at arbitrary irradian
47、ces and correcting to the reference irradiance G1. 6.2 Operating in a controlled environment a) Mount the radiation sensor coplanar with the test device to an agreement better than 2o. b) Set the irradiance to be equal to that of the reference condition G1using the reference device. c) Take simultan
48、eous readings of the open-circuit voltage of the test device VOC2and the incident irradiance (G2). Should there be any variation in the irradiance, treat as a measurement in arbitrary irradiance conditions as given in 6.3 and carry out the appropriate correction. An irradiance correction should be c
49、arried out if the scatter in the determined ECT is more than 1 K. d) Calculate the ECT as described in Clause 7. 6.3 Taking measurements under arbitrary irradiance conditions a) Mount the radiation sensor coplanar with the test device to an agreement better than 2o. b) Take simultaneous readings of the open-circuit voltage of the test device VOC2and the incident irradiance G2. c) Carry out a correction of VOC2to an irradiance equal to G1. d) Calculate the ECT as des
