IEC 60904-5-2011 Photovoltaic devices - Part 5 Determination of the equivalent cell temperature (ECT) of photovoltaic (PV) devices by the open-circuit voltage m.pdf

1、 IEC 60904-5 Edition 2.0 2011-02 INTERNATIONAL STANDARD NORME INTERNATIONALE Photovoltaic devices Part 5: Determination of the equivalent cell temperature (ECT) of photovoltaic (PV) devices by the open-circuit voltage method Dispositifs photovoltaques Partie 5: Dtermination de la temprature de cellu

2、le quivalente (ECT) des dispositifs photovoltaques (PV) par la mthode de la tension en circuit ouvert IEC 60904-5:2011 THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2011 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or uti

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16、dsirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du Service clients ou contactez-nous: Email: csciec.ch Tl.: +41 22 919 02 11 Fax: +41 22 919 03 00 IEC 60904-5 Edition 2.0 2011-02 INTERNATIONAL STANDARD NORME INTERNATIONALE Photovoltaic devices

17、Part 5: Determination of the equivalent cell temperature (ECT) of photovoltaic (PV) devices by the open-circuit voltage method Dispositifs photovoltaques Partie 5: Dtermination de la temprature de cellule quivalente (ECT) des dispositifs photovoltaques (PV) par la mthode de la tension en circuit ouv

18、ert INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE K ICS 27.160 PRICE CODE CODE PRIX ISBN 978-2-88912-366-7 Registered trademark of the International Electrotechnical Commission Marque dpose de la Commission Electrotechnique Internationale 2 60904-5 IEC:2011 CON

19、TENTS FOREWORD . 3 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 . 7 5 Determination of required input parameters 7 6 Procedure 8 6.1 General . 8 6.2 Operating in a cont

20、rolled environment . 8 6.3 Taking measurements under arbitrary irradiance conditions 8 7 Calculation of equivalent cell temperature 8 8 Test report 9 60904-5 IEC:2011 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ PHOTOVOLTAIC DEVICES Part 5: Determination of the equivalent cell temperature (ECT) of

21、photovoltaic (PV) devices by the open-circuit voltage method FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co

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30、 (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct applicat

31、ion of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 60904-5 has been prepared by IEC techni

32、cal committee 82: Solar photovoltaic energy systems. This second edition cancels and replaces the first edition, issued in 1993, and constitutes a technical revision. The main technical changes with regard to the previous edition are as follows: added and updated normative references; added reportin

33、g section; added method on how to extract the input parameters; rewritten method on how to calculate ECT; reworked formulae to be in line with IEC 60891. 4 60904-5 IEC:2011 The text of this standard is based on the following documents: CDV Report on voting 82/595/CDV 82/626/RVC Full information on t

34、he voting for the approval of this standard can be found in the report on voting indicated in the above table. A list of all parts of IEC 60904 series, under the general title Photovoltaic devices, can be found on the IEC website. This publication has been drafted in accordance with the ISO/IEC Dire

35、ctives, Part 2. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirmed, withdrawn, re

36、placed by a revised edition, or amended. 60904-5 IEC:2011 5 INTRODUCTION 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

37、can be observed over the area of the module. Second, as the solar cells 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 det

38、ermining the equivalent cell temperature for on-site measurements of 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 th

39、e device (cells, modules, arrays of one type of module) which equates to the current operating temperature if the entire device were operating uniformly at this junction temperature. 6 60904-5 IEC:2011 PHOTOVOLTAIC DEVICES Part 5: Determination of the equivalent cell temperature (ECT) of photovoltai

40、c (PV) devices by the open-circuit voltage method 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 characteristic

41、s, determining NOCT (nominal operating cell temperature) and translating measured I-V characteristics to other temperatures. This standard applies to linear devices with logarithmic V OCdependence on irradiance and in stable conditions. It may be used for all technologies but one has to verify that

42、there is no preconditioning effect influencing the 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 documen

43、t (including any amendments) applies. IEC 60891, Photovoltaic 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:

44、Requirements for reference solar devices IEC 60904-7, 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 photovol

45、taic (PV) modules Design qualification and type approval 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

46、 The method described below is based on the fact that the open-circuit voltage (V OC ) 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 60904-5 IEC:2011 7

47、equivalent temperature of all the cells 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

48、by the method described here than by any alternative technique. However, as the temperature coefficient drops rapidly at irradiances below 200 W/m 2 , 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

49、 following criteria: 1) The variation of V OCneeds to be linear as defined in IEC 60904-10 with respect to temperature. 2) The variation of V OCneeds 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) The shunt resistances of the device need to be reasonably hig