Volume 1 photovoltaic solar energy 1 39 – standards in photovoltaic technology

Volume 1 photovoltaic solar energy 1 39 – standards in photovoltaic technology Volume 1 photovoltaic solar energy 1 39 – standards in photovoltaic technology Volume 1 photovoltaic solar energy 1 39 – standards in photovoltaic technology Volume 1 photovoltaic solar energy 1 39 – standards in photovoltaic technology Volume 1 photovoltaic solar energy 1 39 – standards in photovoltaic technology Volume 1 photovoltaic solar energy 1 39 – standards in photovoltaic technology

1.39 Standards in Photovoltaic Technology H Ossenbrink, H Müllejans, R Kenny, and E Dunlop, European Commission DG Joint Research Centre, Ispra, Italy © 2012 Elsevier Ltd All rights reserved 1.39.1 1.39.1.1 1.39.1.2 1.39.1.3 1.39.1.4 1.39.1.5 1.39.2 1.39.2.1 1.39.2.2 1.39.2.2.1 1.39.2.2.2 1.39.2.2.3 1.39.2.2.4 1.39.2.3 1.39.2.3.1 1.39.2.3.2 1.39.2.3.3 1.39.2.3.4 1.39.2.3.5 1.39.2.4 1.39.3 1.39.3.1 1.39.3.2 1.39.3.3 1.39.3.4 1.39.3.5 1.39.3.6 1.39.3.7 1.39.4 1.39.5 1.39.5.1 1.39.5.2 1.39.5.2.1 1.39.5.2.2 1.39.5.2.3 1.39.6 1.39.6.1 1.39.6.2 1.39.6.3 1.39.7 Appendix References History The Early PV Development in the United States Establishment of IEC TC82 The European Commission’s Joint Research Centre The Early IEC Standards The Working Groups Standards for Performance Determination of PV Devices Introduction Performance Determination of PV Devices Light sources Measurement Traceability Preconditioning Existing IEC Standards Reference solar devices Measurement conditions Measurement practice Data analysis Device behavior Discussion and Conclusion Reliability Testing of PV Modules Introduction The Beginning of an International Standard for Type Approval Testing Weathering Test or Dedicated Stress to Identify Failure Mechanisms Type Approval Testing Pass/Fail Criteria Environmental Testing Correlation of Reliability Testing with Lifetime Energy Performance and Energy Rating Concentrating PV Standards CPV Design Qualification IEC 62108 Other Standards in Preparation Power rating Trackers CPV system safety Outlook New Technologies Major Markets TC82 Priorities Conclusion 787 787 788 788 788 789 789 789 789 790 790 790 790 790 791 791 791 792 792 792 793 793 793 793 793 793 794 795 795 797 797 798 798 799 799 799 799 799 799 799 800 802 1.39.1 History 1.39.1.1 The Early PV Development in the United States The use of photovoltaic (PV) solar cells on the ground actually started in the United States around 1978 At that time, the technology lead the United States had gained from power supply to spacecrafts, and consequently the governance of key knowledge, had spurred the first prototypes aiming to develop PV as a future electricity source also on the earth Favored by the first oil crisis shock, the United States embarked on a range of demonstration projects aiming to develop cost-effective and reliable terrestrial applica­ tions At the same time, companies that had never produced solar cells entered the field, comprised of not only US oil companies (Arco, Exxon, BP) but also semiconductor companies such as Motorola Comprehensive Renewable Energy, Volume doi:10.1016/B978-0-08-087872-0.00143-8 787 788 Applications The demonstration program, sponsored by the US Department of Energy, assigned to the Jet Propulsion Laboratory (JPL; Pasadena, CA) the task of developing specifications that participants to the program must meet The program as such was rolled out in ‘blocks’ along with the specifications The final, and most influential in terms of standardization, specification was the ‘Block V’ specification (1980), describing a range of environmental and mechanical stress tests PV modules would need to pass before being admitted to the program 1.39.1.2 Establishment of IEC TC82 The experience from this early demonstration program and the approach taken within the JPL specification had laid out one of the foundations for the international standardization process In 1980 when the Commission of the European Union decided to finance a similar ‘PV Pilot Program’ with the European Member States as participants, there was enough dynamics and interest to launch a dedicated technical committee (TC) within the International Electrotechnical Commission (IEC), the partner organization of ISO, with headquarters in Geneva, Switzerland The countries represented at the first TC meeting, now named TC82, were the United States, Canada, Australia, United Kingdom, Germany, France, Spain, Italy, and Japan Mr Leclerque from France was elected as the first chairman, and the Secretariat rested with the United States The scope for the TC82 ‘solar PV energy systems’ was defined as To prepare international standards for systems of photovoltaic conversion of solar energy into electrical energy and for all the elements in the entire photovoltaic energy system In this context, the concept ‘photovoltaic energy system’ includes the entire field from light input to a solar cell to and including the interface with the electrical system(s) to which energy is supplied In the beginning, phase work was organized along three working groups (WGs): WG1 Glossary WG2 Modules, nonconcentrating WG3 Systems Much of the work was concentrated in WG2, which had the task to collect existing standards and develop new ones in the two fields One was regarding the measurements of electrical performance of solar cells and modules and included items like the definition of a reference spectral irradiance, the measurements of spectral response (SR) and current voltage characteristics, and requirements for solar simulators The second focused on the test procedures to be harmonized and prescribed to establish an assessment of the expected reliability and minimum lifetime of terrestrial PV modules 1.39.1.3 The European Commission’s Joint Research Centre In 1982, the European Communities launched a pilot program on PV system, comprising 15 installations in the range of 15–300 kWp, totaling just above MWp Around the same time (1981), the global annual production of terrestrial PV solar cells amounted to less than MWp (in 2010, this quantity was produced every h), and the pilot program intended to stimulate more manufacturing and deployment experience To ensure the technical quality and performance of these installations, the European Commission’s Joint Research Centre (JRC) was put in charge of experimentally verifying not only all the PV module types regarding their electrical performance and expected reliability but also the full installations after commissioning For this purpose, the JRC had set up a specialized laboratory (European Solar Test Installation – ESTI) to perform these verifications according to their in-house specifications 101 (‘Standard Procedures for Terrestrial Photovoltaic Performance Measurements’) and 501 (‘Qualification Test Procedures for Photovoltaic Modules’) It was of strategic importance for the JRC that their specifications were contributing to the TC82 program of work, anticipating that only worldwide standards would contribute to a reliable and performing PV technology However, as the JRC as an international organization did not represent a national committee, a liaison was formed between IEC TC82 and the JRC, in order to allow the experts of ESTI to participate actively in the standards writing process from the end of 1982 onward The JRC specification 501 evolved into the second edition (Spec 502) during 1983, essentially dropping some less important test procedures Its introduction stated This specification lays down the control tests of the Commission of the European Communities, applied by the Joint Research Centre for the qualification of modules for photovoltaic projects funded by the Commission, or upon special request from industry or other organizations The general objective of these tests is to assess relative performances and to identify environmental factors and design features which could affect the attainment of a sufficiently long life-time The results of these tests are an essential part of all the photovoltaic pilot and demonstration plant activities of the Commission, they are also used as reference values for JRC’s monitoring programs 1.39.1.4 The Early IEC Standards The program of work of the IEC WG2 developed rapidly, and already in 1987, the first standard was published (IEC 891, today IEC 60891 ed 2.0), and a range of others describing measurement procedures followed in a short sequence as a series IEC 904 WG3 developed work not only on components such as charge controllers and inverters but also on complete systems The first publication was in 1992 (IEC 1194 – Characteristic parameters of stand-alone photovoltaic (PV) systems, today IEC 61194 – Ed 2) Standards in Photovoltaic Technology 789 The work on standards regarding reliability test procedures took longer, as agreement about altogether 17 test procedures had to be found and the laboratory experience in particular at ESTI had to be taken into account In order to allow the growing number of commercial clients a situation of stability, the JRC published in 1991 Specification 503, titled ‘Qualification Test Procedures for Crystalline Silicon Photovoltaic Modules’ This specification was essentially the content of the first committee draft (CD) of the new IEC 1215, which was still in the review process, anticipating that the publication would follow within years The consensus finding process took until 1993, and only after dropping the description of the UV exposure procedure and deciding upon a 1000 h damp heat test (as opposed to 2000 h) was this major standard which is in its 2nd edition still in use worldwide published as IEC 61215 From today’s view, this standard was and is certainly that which has influenced the development of PV module technology the most as it became mandatory in many public and private procurement programs It represented a fair balance between rigid requirements to ensure at least 20 years of lifetime and sufficient room for development of lower cost PV modules 1.39.1.5 The Working Groups The work of WG2 on measurement procedures around the series IEC 60904 was almost completed; however, the standardization of calibration methods for reference cells (used as reference standards to calibrate PV modules and solar simulators) turned out to be difficult, as the few laboratories had different methods, which produced some discrepancies in a range of round-robin tests It was only in 2009 that a document addressing the traceability of reference cells to SI standards could be published WG3 took on board the safety standards of both stand-alone and grid-connected systems, and in particular the consensus process on the latter was and still is lengthy, as existing national standards are often very different and difficult to harmonize For a short period in the late 1980s, WG4 existed with the scope to include electricity storage systems; however, it was dissolved in favor of a joint WG with TC82, named ‘Accumulator Systems for Photovoltaic Solar Energy’ In 1995, the markets evolved to the situation, which required improving the quality of PV production, deployment, and operation; an industry-developed approval system (PV GAP, photovoltaic Global Approval Program) was reason to establish WG5, titled ‘Accreditation and Certification’ However, the Standard Management Board of the IEC pointed out that such quality assurance systems would be better placed within the IECQ (IEC’s certification program for electronic components, processes, and related materials) organization, and the WG was discontinued After some years, this activity was extended to a comprehensive quality assurance system under IECEE (Conformity Testing and Certification of Electrotechnical Equipment and Components) During the following years, two new WGs have been established, WG6 for ‘Balance of System Components’ (1998) and WG7 for ‘Concentrating modules and systems’ (2003) 1.39.2 Standards for Performance Determination of PV Devices 1.39.2.1 Introduction This section reviews the IEC standards relevant for the determination of the electrical performance of PV devices The electrical performance of a PV device is normally determined as the maximum power it can deliver under well-defined testing conditions It is a key parameter for comparison with other PV devices, whether of the same type, of different type, or even of a different technology The absolute value of maximum power is furthermore an important input for the evaluation of energy rating, that is, the total energy a PV device will produce during operation in the field A common application in industry is to sort the output of a production line according to the electrical power measured on each single device This applies, for example, not only for single cells that are sorted to match them in the PV module into which they will be incorporated but also to finished modules The latter are often sold in power classes, where the same product is sorted according to their real maximum power and priced differently In the field of research and development, the determination of the absolute maximum power (or device efficiency, which is the maximum power divided by the device area) is important to assess the progress of PV device and technology The regularly published PV device efficiency tables [1] give an up-to-date picture of the state of the art and are based on maximum power measurements applying international standards at selected reference institutes The international standards relevant for PV devices and their measurement are developed within TC82 of the IEC The way to new standards is normally paved by scientific research, first by single institutions and then applied by others of the international community This might lead to some national standards Eventually, however, once agreement in the international scientific community has been reached, an IEC standard is prepared The standards relevant for this section are developed by WG2 of TC82 1.39.2.2 Performance Determination of PV Devices In this section, the main elements of the performance determination of PV devices are briefly described The relevant standards will then be reviewed in the next section The determination of electrical performance of PV devices consists of exposing the device to irradiance from a light source and measuring its electrical behavior by a suitable load The measured data are analyzed and the result reported together with the 790 Applications measurement conditions The irradiance intensity is usually determined by a reference device that should provide traceability to the international irradiance scale Care needs to be taken about the (meta-)stability of the device and its state 1.39.2.2.1 Light sources The PV devices are exposed either to natural or to simulated sunlight The latter may be continuous or – especially for practical reasons for large area devices – of a pulsed nature The sun always provides a good quality irradiance to measure PV devices However, a number of practical problems limit the measurements under natural sunlight The main difficulties encountered are that natural sunlight is not reliably available due to weather conditions and the control of the measurement conditions is difficult Therefore, solar simulators are widely used to measure the electrical performance of PV devices They can easily be integrated into a laboratory or production environment and allow measurements to be made at any time independent of weather conditions For smaller devices such as single-crystalline silicon solar cells, continuous source simulators are used, whereas for larger areas, a pulsed light source is more common However, there are also pulsed systems for single cells as well as large area steady-state simulators 1.39.2.2.2 Measurement 1.39.2.2.2(i) IV characteristics The maximum power is determined from a complete current voltage (IV) characteristic that is acquired using a suitable variable load while the PV device is illuminated by the natural or simulated sunlight While the maximum power is defined in IEC 61836, there is actually no guidance given in any of the IEC standards on how to extract it from a measured IV characteristic 1.39.2.2.2(ii) Standard test conditions There are three main parameters that influence the performance of PV devices, namely the device temperature, the total irradiance, and its spectral distribution For easy comparison, standard test conditions (STC) have been defined (see below) They foresee a device temperature of 25 °C and a total irradiance of 1000 W m−2 with a spectral irradiance as defined in IEC 60904-3 (for details see below) The STC are an artificial set of conditions that combine an expected irradiance on a clear day around midday with a device temperature easily achievable in a laboratory environment Under continuous exposure to an irradiance of 1000 W m−2, the PV device would normally equilibrate at a much higher temperature, for example, 50–60 °C Nevertheless, STC cannot be reached exactly and therefore data analysis and processing translate the measurement to STC, which is then reported In the United States, the term standard reporting conditions (SRC) is more common and in effect somewhat more appropriate The STC are the reference conditions for PV device calibration The calibration value of reference devices is quoted for STC In updating IEC 60904-3 from first to second edition, the tabulated reference spectral irradiance distribution was recalculated While maintaining the principal input parameters unchanged, the actual spectrum changed also because a newer version of software was used This improved the resolution of the tabulated spectrum However, it also changed the spectral irradiance distribution somewhat The latter resulted in a shift of the calibration values of PV devices The exact shift depends on the spectral response of the PV device For crystalline silicon PV devices the change led typically to an increase of the short circuit current of +0.7% with a corresponding increase in maximum power In conclusion the calibration values of all PV devices changed due to a redefinition of STC 1.39.2.2.3 Traceability Performing measurements of IV characteristics gives important information and in some cases the results need only be known on a relative scale However, in most cases, absolute results are required Therefore, all instruments used for a measurement have to be calibrated Furthermore, each calibration has to have a traceability chain, which needs to connect to international standards Only under these conditions are absolute performance measurements, or better calibration, achieved The most important instrument used for IV measurements is the reference device that is normally also a PV device, which is regulated by the IEC standards Measurements of current and voltage are, however, not specific to PV and are therefore not included in the IEC series on PV 1.39.2.2.4 Preconditioning PV devices might not always be stable Crystalline silicon remains stable for long time periods after a small initial degradation, whereas thin film devices are susceptible to stronger initial degradation, seasonal variations (during outdoor exposure), or metastable behavior depending on the storage conditions This needs to be taken into account when measuring PV devices, as the result might depend on the history of the PV device as well as on the actual conditions immediately before and during measurement This is a vast field that currently is only partly addressed by international standards, namely the stabilization through controlled light soaking in IEC 61646 1.39.2.3 Existing IEC Standards This section reviews the existing IEC standards applicable to determining the performance of PV devices as described in the previous section, concentrating on the standards regulating traceability, measurement execution, and data analysis These are the IEC 60891 Standards in Photovoltaic Technology 791 and the IEC 60904 series The relevant standards are nominated, briefly described, and where relevant notes on their development are given as background information 1.39.2.3.1 Reference solar devices IEC 60904-2 sets the requirements for reference solar devices The second edition of this standard unites the first editions of IEC 60904-2 (requirements for reference solar cells) and IEC 60904-6 (requirements for reference solar modules), the latter being discontinued IEC 60904-2 addresses the calibration of the reference solar devices together with the requirements for their classification, selection, packaging, marking, and care The calibration traceability chain is mentioned and three levels of reference devices are defined, namely primary, secondary, and working reference devices Furthermore, the calibration procedures for secondary references against a primary reference and working references against a secondary reference are described The crucial point of establishing calibration traceability to SI units (as required by IEC 60904-2) is addressed in IEC 60904-4 ed The calibration chain from primary standards over secondary standards to primary and secondary references is explained and the methods that are in use to transfer between these different levels are mentioned The requirements for traceable calibration procedures are mainly that all instruments used must themselves have unbroken traceability chains, an inherent absolute precision, and documented measurement uncertainty and repeatability Examples of calibration methods for the transfer from secondary standards to primary references are collected in an annex to IEC 60904-4 As far as solar reference devices are concerned, this is the most crucial step, as secondary standards are typically not PV devices but rather of a completely different technology with consequently different properties An example is the absolute cavity radiometer, which has an extended spectral sensitivity and slower response time compared with a PV device The other steps in the calibration and traceability chain have to satisfy the requirements of IEC 60904-4 but they are not described in the standard The transfer between primary and secondary standards is outside its scope as they are normally of non-PV technologies, whereas the transfer between primary and secondary PV reference devices is already addressed in IEC 60904-2 1.39.2.3.2 Measurement conditions Measurement principles for PV devices are defined in IEC 60904-3 together with a definition of the reference spectral irradiance data The description of the measurement principles in this standard is rather short, referring to the other standards Interestingly, it mentions STC without actually defining them or providing a reference In fact they are defined neither in the IEC 60904 series nor in IEC 60891, but in IEC 61836, and in IEC 61215 The larger part of IEC 60904-3 is a table defining the reference spectral irradiance distribution It was obtained from a solar spectral model SMARTS with a certain set of input parameters (CO2 concentration, precipitable water, ozone content, turbidity, and pressure) for a surface tilted 37° to the horizontal and air mass AM1.5 The total integrated irradiance is 1000 W m−2 between and ∞ wavelength It is worth noticing that this defined reference spectrum is not actually observed in nature, although under suitable conditions the measured solar spectrum is very close to it The spectrum is also often called AM1.5G referring to the air mass and that it represents global (direct and diffuse) irradiance IEC 60904-9 concerning the performance requirements of solar simulators is another important standard for measurements In its second edition, each solar simulator can be assigned three different classes (labeled A, B, and C) for the following three criteria: spectral match (to AM1.5G defined in IEC 60904-3), spatial nonuniformity of irradiance in the test plane, and temporal instability of this irradiance The latter is divided into short term (one data triplet of irradiance, current, and voltage) and long term (entire measurement of IV characteristics) The highest class (having best spectral match and lowest nonuniformity and instability) is class A, so a solar simulator best in each of the three criteria would be assigned class AAA Such products are commercially available Some manufac­ turers who claim that their specifications are significantly better than those required to achieve class A have labeled their products class A+, but this is not currently defined in any standard IEC 60904-9 also mentions the measurement procedures for the three criteria It is worth realizing that a class AAA simulator is certainly of a high quality but depending on its application might nevertheless give significant deviations between actual measurement of a PV device and its true value Therefore, even for such a simulator, data analysis and correction as well as a detailed measurement uncertainty analysis are required for quantitative results 1.39.2.3.3 Measurement practice The central measurement required for characterizing a PV device, namely the IV characteristics, is described in IEC 60904-1 ed This standard lays down basic requirements and defines different measurement procedures and guides toward minimizing measurement uncertainty The general requirements are for the measurement of irradiance, temperature, current, and voltage Furthermore, mounting and data correction (see below) are addressed The section on apparatus and measurement procedures are separated for measurements in natural and simulated sunlight, the latter furthermore for steady state and pulsed For data analysis and further measurement requirements, IEC 60904-1 refers to other standards within the series and IEC 60891 For test devices different from the reference device, a spectral mismatch correction is required (see below) that requires the SR as input The measurement of SR is described in IEC 60904-8 (currently under revision) The existing ed defines SR and how it can be determined for a test device with respect to a reference PV device Essentially both devices are illuminated by (quasi-) monochromatic light and the induced short circuit current is measured Three methods for obtaining suitable monochromatic light and measuring the SR are mentioned, namely using a monochromator or bandpass filter together with a steady-state light source and a chopper, or a pulsed solar simulator and bandpass filter 792 Applications 1.39.2.3.4 Data analysis A crucial step in data analysis is to correct from the actual measurement conditions to STC In general, this requires procedures for temperature and irradiance corrections to measured IV characteristics described in IEC 60891 Three methods for IV curve translation are described The first two procedures are mathematical translations of measured IV data pairs and require four correction parameters (the temperature coefficients of short circuit current and open circuit voltage, the internal series resistance, and the curve correction factor) These correction parameters have to be determined according to the methods given in the standard itself, if not know a priori The third correction method is an interpolation method not requiring correction parameters but a minimum of three IV curves spanning the temperature and irradiance range for which correction is required A further important aspect in data analysis is the spectral mismatch between the test and reference device IEC 60904-7 defines the spectral mismatch and its computation It then proceeds to give two methods for correcting the spectral mismatch In the first method, the irradiance is adjusted (normally only possible for simulated sunlight) before performing the IV measurement, which then does not need any further correction for spectral mismatch In the second method, the measured IV curve is translated using IEC 60891, but with the nominal irradiance replaced by an effective irradiance taking into account the spectral mismatch An indispensable part of any data analysis is the evaluation of measurement uncertainties Every component in the measurement and data analysis process has to be considered and the respective uncertainties and their influence on the final result calculated The final results need to be stated together with their uncertainties, because any quantitative statement without its associated measure­ ment uncertainty is worthless Details and the state of the art are given in a comprehensive analysis of measurement uncertainty in PV device calibration [2] 1.39.2.3.5 Device behavior For encapsulated PV devices such as modules, it can be difficult to measure the device temperature with temperature sensors However, an equivalent cell temperature (ECT) can be determined by the open circuit voltage method as described in IEC 60904-5 The ECT is the average temperature of the electronic junctions in the PV device The standard describes its determination based on the open circuit voltage at known temperature and irradiance conditions, the temperature coefficient of the open circuit voltage, and the thermal diode voltage For many methods described in the standards mentioned so far, the linearity of the PV device is required, which can be determined according to IEC 60904-10 Such a linearity check should be performed prior to any measurement or correction procedure, which requires linearity such as those in IEC 60891 The standard describes procedures for determining the degree of linearity and its calculation Finally, it sets requirements for acceptable limits below which the device can be considered linear 1.39.2.4 Discussion and Conclusion The standards described above, IEC 60891 and IEC 60904 series, form a comprehensive set for the determination of the electrical performance of PV devices All standards are applicable to PV devices in crystalline silicon technology However, there are limits of their applicability to thin film technologies and more importantly to multi-junction technologies These limitations are clearly listed in the scope of each single standard, giving hints on possible applications outside An evolution can be observed comparing the current status with that of the original first edition of each standard, which was exclusively for crystalline silicon technology Keeping in mind that these standards were developed in the late 1980s and early 1990s, this might not be surprising as crystalline silicon was the dominating technology at that time However, as thin film technologies have developed, many measurement methods have been applied to them as well and the experience gained led to the inclusion of some of these in the scope of the standards Currently, there remain two areas which are not covered, namely multi-junction (nonconcentrating) PV devices and concentrating devices Standards for the latter are under development (as described in another section), whereas for multi-junction flat-plate PV devices, there is a lack of any IEC standard while the industry is producing such devices in noticeable volumes The great benefit in international standards is that the community has agreed on the measurement methods and therefore the results become comparable on a global scale This aids in the strive for transparency concerning the quality of products and fair markets The development of IEC standards is necessarily a slow process as it is based on international agreements This becomes apparent when, as is the case for multi-junction technology, the development of industrial products progresses much faster than the development of suitable measurement methods This is somewhat alleviated by a small number of international reference laboratories, which actively develop the measurement methods that will eventually be included in the IEC standards Due to the experience and deep insight present in these laboratories, they offer a certain flexibility to apply standards beyond their scope or provide methods and procedures for which no standard yet exists For the much larger number of laboratories providing routine measurements, this does not apply and the published IEC standards need to be strictly followed The near future will certainly see a further inclusion of thin film technologies in the scope of the IEC standards and should also see the development of suitable new standards covering the multi-junction technologies Standards in Photovoltaic Technology 793 1.39.3 Reliability Testing of PV Modules 1.39.3.1 Introduction PV modules purchased and installed in the present-day marketplace have as a minimum requisite type approval or qualification testing, as defined in the document IEC 61215 for crystalline silicon modules or IEC 61646 for thin-film-based modules This type approval testing is often referred to as reliability testing or design qualification; it is not a lifetime test The early days of reliability testing and type approval for PV can be identified as the period in the early mid-1970s when in various parts of the world, and particularly in the United States and Europe, the first national and international programs were being launched to investigate alternatives to nonnuclear or conventional energy sources Programs such as the then European Communities PV Demonstration projects began to offer co-funding of PV systems as demonstration projects Since this co-funding was based on public finance, the funding bodies wished to obtain some form of assurance that these new PV materials could actually operate in an outdoor climate for extended periods This heralded the request to testing bodies and research centers to develop methods to assure the soundness of public and private investments by certifying the reliability of PV modules 1.39.3.2 The Beginning of an International Standard for Type Approval Testing In 1975, the European Commission’s Directorate-General XII and later the Directorate-General XIII (now DG Research and DG Energy, respectively) began promoting PV systems and installations and at the same time asked the JRC to support this promotion In 1977, the European Solar Test Installation of the JRC formally began to study measurement, characterization, and reliability of PV systems In this context, and together with similar activities around the world [3], the search for simple and cost-effective method for reliability testing of PV modules began in earnest 1.39.3.3 Weathering Test or Dedicated Stress to Identify Failure Mechanisms In the world of testing, different theories have been and still are applied For material or components which are well established, it is often sufficient to develop a test which applies multiple stress/acceleration factors (e.g., temperature, humidity, thermal stress, thermal mechanical fatigue, and UV or IR stress) in a single test, a so-called weathering test The benefit of this is that the test can be faster, since it is more extreme and potentially cheaper since it is a single test However, with such a testing method, it is usually very difficult to correlate any resulting defects or failures during the test to a single stress and therefore to improve parts of the module or component design In the early days of module testing, the PV industry was also in its infancy so the approach of applying single or at most double stress factors was adopted This approach brings the advantage that by analyzing the results of multiple stress tests of single or combined stress factors it is possible to establish where the design weakness is in a system This analytical feedback to the module manufacturers allowed a timely correction and improvement of the products, while avoiding the necessity to over engineer (and therefore raise costs) associated with the solution of a problem resulting from a weathering test From this decision, the concept to apply a series of combined tests developed into the first testing standards which were applied [3] 1.39.3.4 Type Approval Testing The IEC type approval standard 61215 for crystalline silicon PV modules lays down IEC requirements for the design qualification and type approval of terrestrial photovoltaic modules suitable for long-term operation in general open-air climates The objective of this test sequence is to determine the electrical and thermal characteristics of the module and to show, as far as is possible within reasonable constraints of cost and time, that the module is capable of withstanding prolonged exposure in climates described in the scope Eight PV modules are selected randomly from the production line to undergo type approval testing One module is kept as a reference module to be used to verify that the measurement method to determine degradation is repeatable, one module is used on the electrical characterization leg, and two modules are used for each of the three environmental test legs The testing scheme is illustrated in Figure 1.39.3.5 Pass/Fail Criteria For crystalline silicon PV modules, in order to declare that if a given module type has been deemed to pass a qualification test sequence, it must meet six pass/fail criteria • First the total degradation of maximum power must be less than 8% after each test leg • There can be no open circuits detected during the test sequence • There must be no major visual defects (e.g., broken, cracked, or torn external surfaces, including superstrates, substrates, frames and junction boxes) • The insulation requirements are met 794 Applications Initial visual inspection (VI)/performance measurement (PS)/insulation test (IN)/preconditioning (PRE)/wet insulation (WIN) VI/PS/WIN Temperature coefficients Ultraviolet exposure 200 Thermal cycles 1000-h damp heat NOCT VI/PS/IN VI/PS/IN/WIN WET leakage test Performance at NOCT 50 Thermal cycles Performance at low irradiance VI/PS/IN Outdoor exposure Humidity freeze Bypass thermal test VI/PS/IN Hot spot endurance VI/PS/WIN Electrical leg Mechanical load Hail resistance VI/PS/IN/WIN Rob termination VI/PS/IN/WIN Environmental leg Environmental leg Environmental leg Figure The IEC 61215 edition schematic of the test sequence NOCT, nominal operation cell temperature • The wet leakage tests are satisfied at the beginning and end of the test sequence • All specific requirements of the individual tests are met An extensive description is given in the IEC 61215 standard In the thin-film type approval standards IEC 61646, the test sequence is derived from IEC 61215 for the design qualification and type approval of terrestrial crystalline silicon PV modules However, it no longer relies on meeting a plus/minus criterion before and after each test sequence, but rather on meeting a specified percentage of the rated minimum power after all of the tests have been completed and the modules have been light soaked This eliminates the technology-specific preconditioning necessary to accurately measure the changes caused by the test The testing criteria and stress levels are outlined in Table for crystalline silicon PV modules 1.39.3.6 Environmental Testing There are three main environmental test legs applied in the standards (see Figure 1) which are intended to separate the individual stress factors: the UV humidity freeze (leg 1), the thermal cycle (leg 2), and the damp heat (leg 3) An analysis of the various defects observed from each of these testing legs can be found in Reference From this study comprising commercial PV module types conducted from 1990 to 2006, the classification of major defects in tested PV modules is related to either visual, loss of power, or Standards in Photovoltaic Technology Table The summary of test levels included in the IEC 61215 edition test sequences Acronym used in the text OE UVE HSP TC50 and TC200 HUF DAH ROB MEL HAR DT 795 Test title Test conditions Outdoor exposure test UV test Exposure to solar irradiation of total of 60 kWh m−2 Hot spot test Thermal cycling test Humidity freeze test Damp heat test Robustness of termination test Mechanical load test Hail test Bypass diode thermal test Exposure to UV irradiation of total of 15 kWh m−2 The UV wavelength range from 280 to 385 nm, with kWh m−2 in the wavelength range from 280 to 320 nm h exposure to 1000 W m−2 irradiance in the worst-case hot-spot conditions 50 and 200 thermal cycles from –40 °C to +85 °C, with STC peak power current during 200 cycles 10 cycles from +85 °C, 85% RH to –40 °C 1000 h at +85 °C, 85% RH Determination of terminations’ capability to withstand appropriate mechanical stress 2.4 kPa uniform load applied for h to front and back surface in turn 25 mm diameter ice ball at 23 m s−1, directed at 11 impact locations h at Isc and 75 °C, h at 1.25 times Isc and 75 °C insulation failures The total number of module types tested was 174, out of those 130 module types (74.7%) passed certification procedure, 27 (15.5%) passed after successful retest, and 17 types (9.7%) were rejected The great majority of failures occur following the environmental tests The reasons for failure can be broadly shared between power loss and major visual defect; the insulation failure occurred only once The most stressful test provoking highest failure rate was the Thermal Cycle Test TC200, suggesting a cause from the high thermomechanical fatigue, which is not observed to the same extent in the case of the TC50 The DAH test still provokes many failures, although encapsulation systems appear to be quite mature in contemporary modules The UVE test provoked much smaller number of failures than the DAH test Mechanical tests provoked very few failures since the mechanical features of the modules are generally well understood; however, these tests can be fatal for nonstandard modules such as nonglass and pole-mounted types 1.39.3.7 Correlation of Reliability Testing with Lifetime The correlation between the results of reliability tests such as the IEC 61215 is often taken as indication of lifetime This is not a correct assumption as the IEC testing does not directly determine degradation factors or estimate the lifetime; rather it sets a minimum level for the PV modules to be considered suitable for long-term outdoor exposure Exactly how long is ‘long term’ is the subject of continuing studies In our paper ‘The Results of Performance Measurements of Field-aged Crystalline Silicon Photovoltaic Modules’ [5], we investigated this correlation In this study, 204 crystalline silicon PV modules following long-term, continuous outdoor exposure were characterized before and after 20 years of outdoor exposure, in order to determine the relative degradation rates and the comparison to the assumption of 20 years lifetime of module certified to IEC type approval standard IEC 61215 We concluded from this study that the effective lifetime of PV modules is considerably greater than 20 years assumed from qualification testing The definition of lifetime is a difficult task as there does not yet appear to be a fixed catastrophic failure point in module aging but more of a gradual degradation Therefore, if a system continues to produce energy which satisfies the user needs, it has not yet reached its end of life These studies and observations are continuing 1.39.4 Energy Performance and Energy Rating Manufacturers of PV modules currently provide a power rating (Pmax) at STC These conditions correspond to an irradiance level of 1000 W m−2 at a defined spectral irradiance distribution (AM1.5) and a module temperature of 25 °C Other electrical information such as Voc and Isc are also typically provided The performance of a PV module at STC is a useful indicator for comparing the peak performance of different module types, but on its own is not sufficient to accurately predict how much energy a module will deliver in the field when subjected to a wide range of real operating conditions The reason for this is because the instantaneous power output of a PV module depends on the cell temperature and the intensity of the incident sunlight, which vary significantly as a function of location, climatic conditions, time of day, and season These are the two principal factors, but others such as solar spectrum, angle of incidence, and soil also affect the performance [6–13] Because the energy production over the module lifetime, or any shorter time period, is crucial in determining its economic viability, there has been much research interest in the performance of modules under real conditions in order to be able to provide a reliable rating for energy production This would also enable differentiation of different modules on the basis of their expected output There exist several proposals for an energy rating for PV modules, which attempt to account for the varying operating conditions that one encounters in the field A simple approach developed at ESTI has an emphasis on simplicity and practicality It is based on the 796 Applications solar irradiance and temperature data that are readily obtainable for many locations Furthermore, the proposed method incorporates existing internationally accepted standard measurements, discussed in other sections, to determine the module’s ‘performance surface’ as a function of global in-plane irradiance and ambient temperature Creating the performance surface using standard indoor tests is an advantage since no new test methods need be established In order to predict energy production for a site of interest from the performance surface, a distribution surface of environmental conditions is required The distribution surface provides an indication of the probability of occurrence of any given combination of irradiance and temperature for that location Other approaches to energy rating or prediction of real module performance are also under development and two approaches in particular are described here A matrix-based energy rating method has been described by workers at The Institute for Applied Sustainability to the Built Environment (ISAAC), SUPSI, Switzerland This method is also based on estimating Pmax as a function of two parameters, irradiance and ambient temperature However, in this case, a performance matrix is compiled from outdoor data measured over a long period of time, typically year Good results for energy prediction have been reported, but a disadvantage of this approach is clearly that a long outdoor measurement period is required in order to create the performance matrix Furthermore, the performance matrix may be influenced by particular conditions of the site at which the measurements take place and may therefore be less suitable for prediction of energy production in other geographical locations Another approach involves the definition of ‘standard days’, which are intended to be representative of different climates types around the world Complex modeling of module performance as a function of several parameters is performed in order to determine the energy rating for these standard locations While certainly comprehensive, and quite possibly accurate, the dis­ advantage of this method is the complexity, which may prove impractical and of uncertain cost benefit Nonetheless, while each of the above approaches has its own advantages and disadvantages, it is largely this last approach that has been the subject of discussion in the IEC TC82 WG2 Due to the complexity and relative lack of data, the draft IEC international standard 61853, ‘Performance Testing and Energy Rating of Terrestrial Photovoltaic (PV) Modules’ was under development for a number of years before it was decided to break it into several parts so that as agreement on each aspect was reached, the relevant part could be published The first part relating to the power rating was finally published in January 2011 The current status of the IEC 61853 standard will be further discussed in the following An extract from the scope for the 61853 series reads “this International Standard series establishes IEC requirements for evaluating PV module performance from both a power (watts) and energy (watt-hours) standpoint” It is further noted that “it is written to be applicable to all PV technologies, but the methodology does not take into account transient behavior such as light induced changes and/or thermal annealing” This means that it is expected to work well in the case of c-Si, but care must be taken with thin film technologies IEC 61853 Part in particular describes requirements for evaluating PV module performance in terms of power (watts) rating over a range of irradiances and temperatures The object is to define a testing and rating system, which provides the PV module power (watts) at maximum power operation for a set of defined conditions A second purpose is to provide a full set of characterization parameters for the module under various values of irradiance and temperature Test methods (which employ the existing IEC standards, such as the 60904 series) are described to enable mapping of module performance over a wide range of temperature and irradiance conditions The range of measurement conditions is then reported in a matrix format provided with the module Even in the absence of the following parts of the series, these data will be valuable to end-users in the estimation of energy production Part 2, currently in draft version only, is expected to describe procedures for measuring the performance effect of the angle of incidence; the estimation of module temperature from irradiance, ambient temperature, and wind speed; and impact of SR on the module performance Part 3, currently in draft version only, is expected to describe the calculations of PV module energy (watt-hours) ratings based on the measurements taken according to the first two parts It will define a rating methodology, which provides the PV module energy (watt-hours) and the performance ratio at maximum power operation for a set of defined ambient conditions Potential applica­ tions are the comparison of various modules or module technologies, prediction of actual module output in a climatic zone, and optimization of module construction for a specific application The final Part 4, again currently in draft version only, describes the standard time periods and weather conditions that can be utilized for calculating energy ratings according to Part It will describe standard time periods and contain the weather data that can be used to simulate the performance of a given module over these periods The current draft defines six reference days with hourly datasets of ambient temperature, direct and diffuse irradiance, wind speed, angle of incidence, and spectral distribution These are given the following acronyms and definitions: HIHT: High Irradiance, High Temperature HILT: High Irradiance, Low Temperature MIMT: Medium Irradiance, Medium Temperature MIHT: Medium Irradiance, High Temperature LILT: Low Irradiance, Low Temperature NICE: Normal Irradiance, Cool Environment IEC 61853 Part is already proving useful to manufacturers and end-users alike in the important task of predicting energy performance in a given installation location This unfortunately still falls short of the ambition to provide an energy rating Standards in Photovoltaic Technology 797 that would need to be a complete standardized method leading to the possibility of energy labeling of modules Due to the complexity, progress has been slow, even limiting the scope to c-Si, but it is hoped that the remaining parts of IEC 61853 will be issued in the near future 1.39.5 Concentrating PV Standards Concentrating PV is the remit of WG7 of IEC TC82, which has already been described in Section 1.39.1 WG7 has approximately 40 members now and meets approximately two times per year The longstanding convenor is Robert McConnell (United States) WG7 (concentrator modules) has the following mission statement: To develop international standards for photovoltaic concentrators and receivers These standards will be in the general areas of safety, photoelectric performance and environmental reliability tests The standards ultimately produced should be universal and non-restrictive in their application, taking into account different environments and manufacturing technologies In addition to the basic electrical and mechanical characteristics, standards will be written for other important factors such as thermal performance, high voltage performance, fault resistance and fault-tolerant design 1.39.5.1 CPV Design Qualification IEC 62108 The first concentrator photovoltaic (CPV) standard published by the IEC is IEC 62108, which covers design qualification and type approval It was published in 2008 and is in fact currently the IEC’s only CPV-specific standard This standard was identified from the beginning by WG7 as being of great importance, since failures in early CPV systems risked the market acceptance of new-generation systems then becoming available It was believed that a strong qualification standard would boost confidence by demonstrating the potential for long term system reliability, a problem that has in the past damaged the reputation of the entire CPV sector At the same time, it was necessary to ensure that the new CPV qualification standard would not be overly difficult to pass in comparison with existing flat-plate PV since this could prevent ground-breaking systems getting to the demonstration phase at all [14–17] IEC 62108 has as its objective the determination of the electrical, mechanical, and thermal characteristics of CPV modules and assemblies and to show, within reasonable constraints of cost and time, that CPV modules and assemblies are capable of withstanding prolonged exposure in open air The standard is an evolution of two earlier standards The first of these is the IEEE 1513 qualification standard, which was published in 2001 The second was IEC 61215, which was already in its second edition in 2005 This standard has been employed successfully to qualify literally hundreds of flat-plate module designs and has been a key part of the success of flat-plate PV to the present day As an aside, we note that IEC 61646 deals specifically with the qualification of thin film modules, but this in turn is based on the earlier IEC 61215 In the development of the standard, much time has been devoted to defining the terms to be used, complicated by the fact that many CPV system topologies are possible, operating over a range of concentration ratios involving different tracking requirements For these reasons, reconciling the need for a ‘universal and nonrestrictive’ standard that can be applied ‘within reasonable constraints of cost and time’ was not an easy challenge It was decided to illustrate the wide range of possible configurations with five basic types These types are the most widely used and should cover most implementations, but other types are not excluded: point-focus dish PV concentrator linear-focus trough PV concentrator point-focus Fresnel lens PV concentrator linear-focus Fresnel lens PV concentrator heliostat PV concentrator New terms, not needed in flat-plate PV, such as concentrator optics, receiver, module, and assembly were defined in order to be able to clearly identify these parts in the test specifications themselves Several of these tests are applied to selected parts of the CPV system for reasons of practicality or cost Since the test sequence is partially based on that specified in IEC 61215, most of the test procedures are similar However, the scope of the standard states “some changes have been made to account for the special features of CPV receivers and modules, particularly with regard to the separation of on-site and in-lab tests, effects of tracking alignment, high current density, and rapid temperature changes, which have resulted in the formulation of some new test procedures or new requirements” For example, the outdoor exposure test, the UV conditioning test, the damp heat and humidity freeze tests, and the maximum cell temperature and the thermal cycling tests have been modified significantly to be adapted to the requirements of CPV Furthermore, the technical difficulties in measuring the performance of CPV modules on simulators, allied with the current lack of a CPV power rating standard, mean that side-by-side measurements using a reference module have to be used to determine module degradation The potentially large size of some CPV systems meant that it was necessary to allow the option for the outdoor exposure test to be performed by an on-site witness 798 Applications The main differences between IEEE 1513 and IEC 62108 lie in the number and order of the tests applied to the modules and receivers in the qualification tests program and the CPV topologies included – IEEE 1513 takes into consideration only three types compared to the five in IEC 62108 Although IEC 62108 has been recently introduced, discussion of a revision is ongoing due to some issues identified by test labs and manufacturers One difficulty is that measuring the cell temperature during thermal cycling is not practical The requirement to cycle the current (because it can cause too high cell temperatures and nonrepresentative cell failures due to reverse currents) may be dropped from the standard Retest guidelines are also being discussed, similar to those that exist for flat-plate modules to guide test labs in how to limit the test sequence to reduce costs when designs are modified 1.39.5.2 Other Standards in Preparation The current lack of other CPV standards is of concern to the CPV community In their absence, reference has to be made to flat-plate standards that may not be strictly applicable or else manufacturers have to make their own de facto standards that can lead to confusion in the marketplace Happily, several work items covering the most important areas are currently at an advanced draft stage, and they will be summarized here The most urgent of these are the following: – Power and energy rating – Tracker standard – Safety standard 1.39.5.2.1 Power rating Probably the most important standard currently missing relates to the performance rating This means that there is no agreed definition of STC that should be used in CPV and furthermore there is no official procedure for rating the electrical performance It is the difficulty in reaching an agreement on the test and operating conditions that has delayed the issue of this standard, together with technical difficulties in actually performing tests and performance measurement translations Although no IEC standard exists for power rating CPV, an ASTM standard E2527 [18]) has been available for several years The standard under development in WG7 (IEC 62670 Power Rating Draft Standard) will allow both indoor and outdoor methods Outside the WG7, but of importance to CPV power rating, a new DNI spectrum (ASTM G173) has been defined to suit the requirements of present and future CPV systems [19] As explained by Emery et al [20], the previous direct reference spectrum was not representative of sunny conditions in regions with a high annual direct normal energy where concentrators might be deployed (in the United States, this is termed the ‘the Sun Belt’) Historically, this issue did not matter because at a given total irradiance and cell temperature under direct, global, or clear-sky natural sunlight, single-junction concentrator PV cells produced a similar short circuit current In contrast, the short circuit current of GaInP/GaAs/Ge triple-junction cells are much more sensitive to spectral variations This sensitivity to spectrum becomes problematic if the indoor measurement spectrum differs significantly from the spectra that are typically observed outdoors The new DNI spectrum improves this situation The choice of STC rating conditions for CPV is still causing serious debate Options are 850, 900, and 1000 W m−2 direct irradiance; 900 W m−2 is a serious contender since the ASTM G173 direct spectrum integrates very close to this value The latest consensus as of September 2011 is for the choice of 1000 W m−2 for the pragmatic reason that it permits direct comparison with flat-plate ratings Test temperature is also an issue, but a standard test temperature of 25 °C currently appears most likely [21] A lot of effort has been directed toward defining specifications for indoor simulators that need to be collimated to measure STC and also how to measure outdoor standard operating conditions (exact conditions still undefined) and translation between these 1.39.5.2.1(i) IEC 62670-2 Energy rating draft technical specification (energy rating by measurement) A method of energy rating by measurement (closely related to the performance ratio concept) has been accepted as a new work item by TC82 The method employs outdoor monitoring over a minimum period of months The data are then analyzed in order to provide an energy rating for the tested system 1.39.5.2.1(ii) CPV cell specification The standard (or guideline) is basically designed to provide a blank specification for cell manufacturers to provide cell data in a consistent manner The guidelines will not provide test methods for measuring cell electrical parameters Standards in Photovoltaic Technology 1.39.5.2.2 799 Trackers Trackers are used for traditional and CPV systems, but generally have more stringent tracking requirements for CPV applications due to their typically very small acceptance angle A draft technical specification for tracker manufacturers has been assigned the number 62627 This will ensure that tracker performance parameters are clearly defined and so customers can compare specifications 1.39.5.2.3 CPV system safety A draft standard for the safety of CPV systems has been assigned the number 62688 Specific topics will be provided to assess the prevention of electrical shock, fire hazards, and personal injury due to mechanical and environmental stresses This standard will be designed so that its test sequence can coordinate with those of IEC 62108, so that a single set of samples may be used to perform both the safety and performance evaluation of a CPV module and assembly 1.39.6 Outlook IEC TC82 has now 33 participating countries and 14 observer countries covering all continents More than 150 experts contribute to the WGs, making TC82 well prepared to accelerate the pace of international standardization The work program ahead requires continuously updating the already published standards in order to take into account progress in technology, measurement procedures, and feedbacks from both the PV manufacturing industry and the system operators Since the establishment of TC82, the PV industry has grown by more than a factor of 1000, and forecasts anticipate a continued growth of at least 25% per year Costs have decreased close to 100 US$ m−2 or 1000 US$ kWp−1, making PV an attractive choice to cover peak supply by professional grid operators The roof-top market will also continue to grow, as national incentive schemes around fixed feed-in-rates make PV very attractive for residential homeowners also Furthermore, even if difficult to quantify, rural electrification systems seem to grow at the same rate as grid-connected systems, in particular due to the availability of mature mini-grid and hybrid systems for village electrification 1.39.6.1 New Technologies PV technology development is not at its end Thin film technologies like a-Si-based tandems, CdTe, and CIS technologies are mature, exhibiting the same lifetime as standard crystalline silicon technology Further, R&D on concentrator cells, modules, and systems has progressed continuously, making these technologies mature for utility markets The early creation of WG7 that has meanwhile published a number of standards is an excellent example of how an anticipating standards policy actually accelerates innovation and allows a fast market take-up To this end, IEC TC82 will soon embark on work on the latest organic cell technologies 1.39.6.2 Major Markets With the massive deployment of PV systems, safety is of an increasing concern, in particular regarding roof-top installations The current situation that the fire risk in millions of roof-top systems is quite low is due to the continuous efforts on international standardization of safety tests and installation requirements However, as many national regulations have to be met in this field, consensus on CDs is still difficult to achieve A similar situation is observable in harmonizing standards for grid-feeding inverters, where many contradictions still exist in national, utility-based regulation 1.39.6.3 TC82 Priorities The principal mandate of the International Electrotechnical Commission is to contribute to the reduction or abolition of trade barriers between WTO (World Trade Organization) countries, as it allows innovation, competition, and lastly a reduction of costs Therefore, the major priorities for work of TC82 are standards for these global markets on wafers, solar cells, modules, system components, and entire systems More and swifter standards are required for inverters, safety, the grid interface, electromagnetic compatibility, recycling/disposal at the end of life, and the use of materials compatible with environmental standards 1.39.7 Conclusion TC82 is certainly a very successful committee of the IEC when measured against the impact on this relatively new energy technology The standards established are today in use worldwide and have guided the whole value chain of PVs The exactly 30 years of efforts of TC82 have contributed to millions of PV systems that today deliver reliable and continuous electricity, indifferent applications, sizes, and climates 800 Applications Appendix Past Chairmen of TC82 1982: M Leclerque, France 1992: Y Sekine, Japan 1997: R DeBlasio, USA Since 2004, H Ossenbrink, EU (as part of the German National Committee) IEC Standards Published (2011) IEC 60891 Edition 2.0 (14 December 2009) IEC 60904-1 Edition 2.0 (13 September 2006) IEC 60904-2 IEC 60904-3 Edition 2.0 (20 March 2007) Edition 2.0 (9 April 2008) IEC 60904-4 Edition 1.0 (9 June 2009) IEC 60904-5 Edition 2.0 (17 February 2011) IEC 60904-7 Edition 3.0 (26 November 2008) IEC 60904-8 Edition 2.0 (26 February 1998) IEC 60904-9 IEC 60904-10 IEC 61194 IEC 61215 Edition 2.0 (16 October 2007) Edition 2.0 (17 December 2009) Edition 1.0 (15 December 1992) Edition 2.0 (27 April 2005) IEC 61345 IEC 61646 Edition 1.0 (26 February 1998) Edition 2.0 (14 May 2008) IEC 61683 Edition 1.0 (25 November 1999) IEC 61701 IEC 61702 IEC 61724 Edition 1.0 (22 March 1995) Edition 1.0 (22 March 1995) Edition 1.0 (15 April 1998) IEC 61725 IEC 61727 IEC 61730-1 Edition 1.0 (30 May 1997) Edition 2.0 (14 December 2004) Edition 1.0 (14 October 2004) IEC 61730-2 Edition 1.0 (14 October 2004) IEC 61829 Edition 1.0 (31 March 1995) IEC/TS 61836 IEC 61853-1 Edition 2.0 (13 December 2007) Edition 1.0 (26 January 2011) IEC 62093 Edition 1.0 (29 March 2005) IEC 62108 Edition 1.0 (7 December 2007) IEC 62109-1 Edition 1.0 (28 April 2010) IEC 62109-2 Edition 1.0 (23 June 2011) IEC/PAS 62111 Edition 1.0 (29 July 1999) Photovoltaic devices – Procedures for temperature and irradiance corrections to measured I-V characteristics Photovoltaic devices – Part 1: Measurement of photovoltaic current-voltage characteristics Photovoltaic devices – Part 2: Requirements for reference solar devices Photovoltaic devices – Part 3: Measurement principles for terrestrial photovoltaic (PV) solar devices with reference spectral irradiance data Photovoltaic devices – Part 4: Reference solar devices – Procedures for establishing calibration traceability Photovoltaic devices – Part 5: Determination of the equivalent cell temperature (ECT) of photovoltaic (PV) devices by the open-circuit voltage method Photovoltaic devices – Part 7: Computation of the spectral mismatch correction for measurements of photovoltaic devices Photovoltaic devices – Part 8: Measurement of spectral response of a photovoltaic (PV) device Photovoltaic devices – Part 9: Solar simulator performance requirements Photovoltaic devices – Part 10: Methods of linearity measurement Characteristic parameters of stand-alone photovoltaic (PV) systems Crystalline silicon terrestrial photovoltaic (PV) modules – Design qualification and type approval UV test for photovoltaic (PV) modules Thin-film terrestrial photovoltaic (PV) modules – Design qualification and type approval Photovoltaic systems – Power conditioners – Procedure for measuring efficiency Salt mist corrosion testing of photovoltaic (PV) modules Rating of direct coupled photovoltaic (PV) pumping systems Photovoltaic system performance monitoring – Guidelines for measurement, data exchange and analysis Analytical expression for daily solar profiles Photovoltaic (PV) systems – Characteristics of the utility interface Photovoltaic (PV) module safety qualification – Part 1: Requirements for construction Photovoltaic (PV) module safety qualification – Part 2: Requirements for testing Crystalline silicon photovoltaic (PV) array – On-site measurement of I-V characteristics Solar photovoltaic energy systems – Terms, definitions and symbols Photovoltaic (PV) module performance testing and energy rating – Part 1: Irradiance and temperature performance measurements and power rating Balance-of-system components for photovoltaic systems – Design qualification natural environments Concentrator photovoltaic (CPV) modules and assemblies – Design qualification and type approval Safety of power converters for use in photovoltaic power systems – Part 1: General requirements Safety of power converters for use in photovoltaic power systems – Part 2: Particular requirements for inverters Specifications for the use of renewable energies in rural decentralized electrification (Continued ) Standards in Photovoltaic Technology 801 (Continued ) IEC Standards Published (2011) IEC 62116 Edition 1.0 (24 September 2008) IEC 62124 IEC 62253 Edition 1.0 (6 October 2004) Edition 1.0 (15 July 2011) IEC 62446 Edition 1.0 (13 May 2009) IEC 62509 Edition 1.0 (16 December 2010) Test procedure of islanding prevention measures for utility-interconnected photovoltaic inverters Photovoltaic (PV) stand alone systems – Design verification Photovoltaic pumping systems – Design qualification and performance measurements Grid connected photovoltaic systems – Minimum requirements for system documentation, commissioning tests and inspection Battery charge controllers for photovoltaic systems – Performance and functioning Recommendations for small renewable energy and hybrid systems for rural electrification IEC/TS 62257-1 IEC/TS 62257-2 IEC/TS 62257-3 IEC/TS 62257-4 IEC/TS 62257-5 IEC/TS 62257-6 IEC/TS 62257-7 IEC/TS 62257-7-1 IEC/TS 62257-7-3 Edition 1.0 (11 August 2003) Edition 1.0 (27 May 2004) Edition 1.0 (10 November 2004) Edition 1.0 (25 July 2005) Edition 1.0 (13 July 2005) Edition 1.0 (22 June 2005) Edition 1.0 (9 April 2008) Edition 2.0 (29 September 2010) Edition 1.0 (9 April 2008) IEC/TS 62257-8-1 Edition 1.0 (21 June 2007) IEC/TS 62257-9-1 IEC/TS 62257-9-2 IEC/TS 62257-9-3 IEC/TS 62257-9-4 IEC/TS 62257-9-5 Edition 1.0 (9 September 2008) Edition 1.0 (9 October 2006) Edition 1.0 (9 October 2006) Edition 1.0 (9 October 2006) Edition 1.0 (21 June 2007) IEC/TS 62257-9-6 Edition 1.0 (19 September 2008) IEC/TS 62257-12-1 Edition 1.0 (21 June 2007) Part 1: General introduction to rural electrification Part 2: From requirements to a range of electrification systems Part 3: Project development and management Part 4: System selection and design Part 5: Protection against electrical hazards Part 6: Acceptance, operation, maintenance and replacement Part 7: Generators Part 7-1: Generators – Photovoltaic generators Part 7-3: Generator set – Selection of generator sets for rural electrification systems Part 8-1: Selection of batteries and battery management systems for stand-alone electrification systems – Specific case of automotive flooded lead-acid batteries available in developing countries Part 9-1: Micropower systems Part 9-2: Microgrids Part 9-3: Integrated system – User interface Part 9-4: Integrated system – User installation Part 9-5: Integrated system – Selection of portable PV lanterns for rural electrification projects Part 9-6: Integrated system - Selection of Photovoltaic Individual Electrification Systems (PV-IES) Part 12-1: Selection of self-ballasted lamps (CFL) for rural electrification systems and recommendations for household lighting equipment Standardization Work in Progress IEC 61730-2 Ed 2.0 IEC 62670-1 Ed 1.0 IEC 62688 Ed 1.0 IEC 62716 Ed 1.0 IEC 61853-2 Ed 1.0 IEC 62548 Ed 1.0 IEC 61701 Ed 2.0 IEC 61683 Ed 2.0 IEC 62109-3 Ed 1.0 IEC 62109-4 Ed 1.0 IEC 62670-2 Ed 1.0 IEC 62759-1 Ed 1.0 IEC/TS 62738 Ed 1.0 IEC/TS 62748 Ed 1.0 IEC/TS 62727 Ed 1.0 Photovoltaic (PV) module safety qualification – Part 2: Requirements for testing Concentrator photovoltaic (CPV) module and assembly performance testing and energy rating – Part 1: Performance measurements and power rating – Irradiance and temperature Concentrator photovoltaic (CPV) module and assembly safety qualification Ammonia corrosion testing of photovoltaic (PV) modules Photovoltaic (PV) module performance testing and energy rating – Part 2: Spectral response, incidence angle and module operating temperature measurements Design requirements for photovoltaic (PV) arrays Salt mist corrosion testing of photovoltaic (PV) modules Photovoltaic systems – Power conditioners – Procedure for measuring efficiency Safety of power converters for use in photovoltaic power systems – Part 3: Controllers Safety of power converters for use in photovoltaic power systems – Part 4: Particular requirements for combiner box Concentrator photovoltaic (CPV) module and assembly performance testing and energy rating – Part 2: Energy rating by measurement Transportation testing of photovoltaic (PV) modules – Part 1: Transportation and shipping of PV module stacks Design guidelines and recommendations for photovoltaic power plants PV systems on buildings Specification for solar trackers used for photovoltaic systems (Continued ) 802 Applications (Continued ) Standardization Work in Progress Proposed new work PNW 82-654 Ed 1.0 PNW 82-655 Ed 1.0 PNW 82-665 Ed 1.0 PNW 82-666 Ed 1.0 PNW 82-668 Ed 1.0 PNW 82-669 Ed 1.0 PNW 82-673 Ed 1.0 PNW 82-674 Ed 1.0 PNW 82-675 Ed 1.0 PNW 82-676 Ed 1.0 PNW/TS 82-652 Ed 1.0 Photovoltaic devices – Part11: Measurement of initial light-induced degradation of crystalline silicon solar cells and photovoltaic modules Cross-linking degree test method for Ethylene-Vinyl Acetate applied in photovoltaic modules – Differential Scanning Calorimetry (DSC) Future IEC 6XXXX-1-2: Measurement procedures for materials used in photovoltaic modules – Part 1-2: Encapsulants – Measurement of volume resistivity of photovoltaic encapsulation and backsheet materials Future IEC 6XXXX-1-4: Measurement procedures for materials used in Photovoltaic Modules – Part 1-4: Encapsulants – Measurement of optical transmittance and calculation of the solar-weighted photon transmittance, yellowness index, and UV cut-off frequency Future IEC 6XXXX-1-3 Ed.1: Measurement procedures for materials used in photovoltaic modules – Part 1-3: Encapsulants – Measurement of dielectric strength Future IEC 6XXXX-1-5 Ed.1: Measurement procedures for materials used in photovoltaic modules – Part 1-5: Encapsulants – Measurement of change in linear dimensions of sheet encapsulation material under thermal conditions Concentrator photovoltaic (CPV) solar cells and cell-on-carrier (COC) assemblies – Reliability qualification Junction boxes for photovoltaic modules – Safety requirements and tests Connectors for DC-application in photovoltaic systems – Safety requirements and tests Dynamic mechanical load testing for photovoltaic (PV) modules Specification for concentrator cell description Member States of IEC TC82 (2011) Austria (P) Australia (P) Belgium (P) Bulgaria (O) Brazil (O) Canada (P) Switzerland (P) China (P) Cyprus (P) Czech Rep.(P) Germany (P) Denmark (P) Algeria (P) Spain (P) Finland (P) France (P) UK (P) Hungary (O) Indonesia (P) Ireland (P) Israel (P) India (P) Iran (O) Italy (P) Japan (P) Kenya (P) Korea, Republic of (P) Malaysia (P) Nigeria (P) The Netherlands (P) Norway (P) New Zealand (O) Oman (O) Poland (O) Portugal (P) Romania (P) Serbia (O) Russian Federation (P) Sweden (O) Singapore (O) Slovenia (O) Thailand (P) Turkey (O) Ukraine (O) USA (P) South Africa (P) (P): Participating (O): Observer References [1] Green MA, Emery K, Hishikawa Y, et al (2011) Solar cell efficiency tables (version 38) Progress in Photovoltaics: Research and Applications 19(5): 565–572 [2] Müllejans H, Zaimann W, and Galleano R (2009) Analysis and mitigation of measurement uncertainties in the traceability chain for the calibration of photovoltaic devices Measurement Science and Technology 20: 1–12 [3] Osterwald CR and McMahon TJ (2009) History of accelerated and qualification testing of terrestrial photovoltaic modules: a literature review Progress in Photovoltaics: Research and Application 17: 11–33 [4] Skoczek A, Sample T, Dunlop ED, and Ossenbrink H (2008) Electrical performance results from physical stress testing of commercial PV modules to the IEC 61215 test sequence Solar Energy Materials & Solar Cells 92: 1593–1604 [5] Skoczek A, Sample T, and Dunlop ED (2009) The results of performance measurements of field-aged crystalline silicon photovoltaic modules Progress in Photovoltaics: Research and Application 17: 227–240 [6] Bucher K (1995) 13th European Photovoltaic Solar Energy Conference, pp 2097–2103 [7] Kroposki B, Myres D, Emery K, et al (1996) Photovoltaic module energy rating methodology development In: 25th IEEE Photovoltaic Specialists Conference [8] King DL, Kratochvil JA, Boyson WE, and Bower WI (1998) Field experience with a new performance characterization procedure for photovoltaic arrays In: 2nd World Conference and Exhibition on Photovoltaic Solar Energy Conversion Vienna, Austria, 6–10 July [9] Anderson D, Sample T, and Dunlop E (2001) Obtaining module energy rating from standard laboratory measurements In: Proceedings of the 17th European PV Solar Energy Conference Munich, October 2001 [10] Kenny RP, Dunlop ED, Sample T, et al (2002) Energy rating of diverse PV module technologies through indoor and outdoor characterisation In: 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International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen [16] Muñoz E, Vidal PG, Nofuentes G, et al (2009) Standardization in concentrator photovoltaics In: 24th European Photovoltaic Solar Energy Conference Hamburg, 21–25 September [17] McConnell R and Ji L (2007) Concentrator photovoltaic standards In: 4th International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen El Escorial, Madrid [18] ASTM International (2006) ASTM E 2527-06 Standard Test Method for Rating Electrical Performance of Concentrator Terrestrial Photovoltaic Modules and Systems under Natural Sunlight ASTM International, USA [19] ASTM International (2008) ASTM G173-03 Standard Tables for Reference Solar Spectral Irradiances: Direct Normal and Hemispherical on 37 Tilted Surfaces [20] Emery K, Myers D, and Kurtz S (2002) What is the appropriate reference spectrum for characterizing concentrator cells? In: Proceedings 29th IEEE PV Specialists Conference New Orleans, LA, USA, 20–24 May [21] Kurtz S, et al (2010) Considerations for how to rate CPV In: 6th International Conference on Concentrating Photovoltaic Systems (CPV-6) Freiburg, Germany, 7–9 April  ... Edition 1. 0 (25 November 19 99) IEC 617 01 IEC 617 02 IEC 617 24 Edition 1. 0 (22 March 19 95) Edition 1. 0 (22 March 19 95) Edition 1. 0 (15 April 19 98) IEC 617 25 IEC 617 27 IEC 617 30 -1 Edition 1. 0 (30 May 19 97)... 1. 0 (26 January 2 011 ) IEC 62093 Edition 1. 0 (29 March 2005) IEC 6 210 8 Edition 1. 0 (7 December 2007) IEC 6 210 9 -1 Edition 1. 0 (28 April 2 010 ) IEC 6 210 9-2 Edition 1. 0 (23 June 2 011 ) IEC/PAS 6 211 1... in Photovoltaic Technology 8 01 (Continued ) IEC Standards Published (2 011 ) IEC 6 211 6 Edition 1. 0 (24 September 2008) IEC 6 212 4 IEC 62253 Edition 1. 0 (6 October 2004) Edition 1. 0 (15 July 2 011 )