Streamlining Due Diligence with the IECRE

Imagine that your task is to determine the insurance rate for lifetime coverage on a PV plant. It is easy enough to predict the lifetime of a PV module as 25 years with an indicated uncertainty of plus or minus 25 years. Unfortunately, it is considerably more difficult to predict the lifetime of a PV power plant with a small amount of uncertainty. The latter is the type of prediction that the investment community and other stakeholder groups require to have confidence that a PV asset will deliver an anticipated return on investment.

The consensus among industry stakeholders is that a module design qualification standard alone is not adequate to provide this level of confidence. Instead, stakeholders require quality assurance standards at every step along the value chain: for the materials used in manufacturing; module design; manufacturing process control; equipment selection for the specific climate and installation conditions; system design; shipping, handling and installation; and, finally, O&M after deployment. This requires a comprehensive approach to quality assurance.

International Standardization

The International Electrotechnical Commission (IEC) is the world’s leading organization providing international standards for devices that use or produce electricity. To assure quality in emergent renewable energy sectors, the IEC developed and launched a comprehensive certification system known as the IEC System for Certification to Standards Relating to Equipment for Use in Renewable Energy Applications or more simply the IECRE.

Founded in 2014, the IECRE covers wind energy, marine energy and solar photovoltaic energy sectors. It aims to improve these industry sectors by facilitating the international trade of equipment and services while maintaining high standards of safety and quality. To this end, IEC Technical Committee 82, the working group responsible for PV energy systems, publishes standards that relate to all the elements making up PV systems, and the IECRE incorporates these standards and defines how to implement them.

Since comprehensive quality assurance is complex and requires numerous steps, the IECRE addresses every stage of development in PV power plants, as shown in Table 1. The goal of the IECRE is to develop an efficient, effective and widely adopted quality assurance system, capable of meeting the needs of nations that wish to participate as well as those of national, regional and local organizations.

Benefits of the IECRE. Though independent engineers and other stakeholders are adept at doing due diligence, the IECRE can improve this process by eliminating redundancies. PV projects typically have multiple stakeholders, including manufacturers, engineers, investors and insurers. Often each of these parties has a different protocol for quality assurance, which can create testing redundancies that add costs without providing meaningful benefits.

Standardization not only streamlines the due diligence process, saving time and expense, but also improves practices across the industry by leveraging the extensive international experience available today. The IECRE leverages the experience of the industry and incorporates the practices that experts have identified as most useful. The transfer of scientific and industry expertise facilitates the training of designers, installers and maintenance personnel. The IECRE also implements continual improvement processes that enhance learning and allow manufacturers to change technologies and adapt manufacturing techniques over time without sacrificing quality.

In addition to setting a high bar for quality, the IECRE aims to reduce costs by increasing stakeholder confidence. When system damage occurs, for example, a universally accepted certification of quality and project condition can reduce conflict over its source. Imagine that a Level 4 hurricane has hit a PV power plant, leading to discussions about the extent of the weather-related damages. The insurer might question whether subtle damages, such as cracked cells or hot spots, occurred during the hurricane or during manufacturing, shipping or installation. Using the IECRE certification process to thoroughly document quality and condition over time—from point of manufacturing to time of commissioning and annually thereafter—can provide stakeholders with the information necessary to identify the cause of damage and the responsible party.

Certification bodies and test labs also benefit from uniform application of the IEC standards, including those listed in Table 2. Participating countries and certification bodies mutually accept test results and certificates; that reciprocity is a fundamental principle of the IECRE. A peer assessment process ensures uniform application of the requirements for certification. Internationally standardized procedures not only facilitate agreement between stakeholders but also provide a system to resolve conflict. Process standardization simplifies contract writing.

A good quality management system such as the IECRE is especially critical in a market that is characterized by tight margins and intense price competition. The industry relies on effective international quality assurance to avoid quality control failures. Widespread failures could have persistent consequences, such as higher customer acquisition and insurance costs or loss of public and government support.

Finally, effective quality assurance increases energy production. TÜV Rheinland estimates that a 1% increase in energy production produces a fringe benefit of roughly $5 million per 100 MW of PV capacity. To put these potential benefits in perspective, the US installed nearly 15 GW of PV in 2016, bringing its total capacity to more than 40 GW. Since improved quality assurance also reduces the time and material costs associated with repairs, replacements and recalls, the potential industry-wide savings are even greater.

IECRE Certifications

The IECRE for the solar sector includes a currently available comprehensive set of certifications covering parameters including component quality and annual plant performance. Other certifications are still in draft form or under development.

Component quality. In January 2016, the IEC published the first edition of a technical specification, IEC TS 62941, that provides guidelines for increasing confidence in PV module design qualification and type approval. To guide the review process for PV factory audits and manufacturing quality system certification, the IECRE includes a 3-part operational document, OD-405, for manufacturers and auditors. In effect, IEC TS 62941 establishes technical design engineering and quality management standards, and OD-405 clarifies how to implement them.

Manufacturing facilities qualified to IECRE standards need to demonstrate good quality control. To do so, they must use recognized methodologies, such as statistical process control, and failure mode and effects analysis. These methodologies use monitoring and measurement throughout the manufacturing process to ensure consistent quality during mass production. Process monitoring is critical because a change in materials could cause field problems that, while not apparent at first, appear years later. IECRE-certified factories are also required to have a materials quality assurance plan in place to control for contamination and ensure that materials and components consistently meet specifications.

Since electrostatic discharge causes bypass diode failures, industry stakeholders added a control for electrostatic discharge to IEC 62941. The technical specification also includes steps to verify the proper use of performance measurement equipment so that manufacturers label and bin accurately. These steps include regular calibration of solar simulators and temperature control of the module during measurement. Traceability requirements in the technical standard call for manufacturers to inform customers of a defective product. The ability to track production time or manufacturing lots also enhances continual improvement from field performance, another certification requirement. Feedback can facilitate design improvements, a reduction in manufacturing variability or both.

The IECRE includes training materials for auditors to ensure that audits to IEC 62941 are implemented consistently. Without certification, it is unclear whether factory auditors are capable of accurately auditing module-manufacturing facilities. IECRE certification combined with peer reviews can ensure consistent factory audits internationally.

PV project completion. In June 2017, the IEC approved the publication of the first edition of a technical specification, IEC TS 63049, that provides quality assurance guidelines for PV system installation and O&M. The IECRE includes an operational document, OD-401, which defines how to implement IEC TS 63049 and more than a dozen other IEC standards to verify that a PV system is deployed as originally designed and is ready for operation. Reviewing the specifics of each PV plant as outlined in OD-401 effectively ensures that project stakeholders meet the quality assurance and continual review requirements in the installation and O&M technical specification.

The influx of new workers to the rapidly growing solar sector presents a challenge in terms of maintaining both safety and quality assurance standards. Therefore, the IECRE mandates installer training and continual monitoring. This is an important quality assurance step, as TÜV Rheinland estimates that roughly 50% of PV plant defects are incurred during the installation process.

Properly trained installers understand that it is important not to drop, twist or bend modules. Improper handling—such as carrying a module overhead with the weight resting on a hard hat—can crack PV cells and lead to hot spots. It is likewise important not to walk or kneel on modules during the installation process. Adjusting mounting hardware too loosely or too tightly can also damage modules. Since today’s modules often have thinner glass, thinner frames and larger collector areas compared to earlier products, they tend to have a lower tolerance for mishandling. System performance also suffers when installers connect mismatched modules or unequal string lengths to the same inverter or maximum power point tracker.

It is also important to monitor and track system performance to detect installation errors. Some errors, such as reverse polarity on PV source circuits, can dramatically reduce system performance right out of the gate. Other issues, such as scraped or punctured backsheets, only manifest with the passage of time. Recordkeeping and tracking not only allow for traceability but also provide a feedback mechanism that enhances learning. To the extent that you identify potential problems in advance, you can correct them at the project completion stage, before they have an adverse impact on performance and reliability.

The guidelines in the IEC 63049 technical standard also call for application-specific design adaptation. Consider a PV plant installed at a location that frequently experiences heavy snow loads or large hail, where the standard mechanical load tests, detailed in IEC 61215, may not provide a good indication of long-term reliability. In this scenario, you may want to use modules tested to enhanced mechanical loads and constructed with deeper frames or thicker glass, given the expected snow or hail loads. Designers could also opt for steeper or taller mounting systems where damage due to snow buildup and shedding is a concern. Similarly, quality designs can account for environmental conditions such as high wind loads, corrosion and extreme temperatures.

Test methodology is also an important consideration. Infrared (IR) thermography, for example, can enable rapid, economical detection of certain defects. With an appropriate temperature scale and resolution, IR testing has the potential to reveal a number of problems in fielded modules, including hot spots, bypass diode defects, solder bond failures, mechanically damaged cells and so forth. While aerial IR surveys may be most appropriate for some utility-scale PV plants, IR camera apps for cell phones may be adequate for surveying smaller systems.

Annual PV plant performance. A PV system energy test evaluates plant performance over time by comparing predicted and expected performance. Whereas predicted energy is based on historical weather data, expected energy is based on actual weather over the 1-year test period. These long-term energy test results provide valuable documentation regarding long-term PV system performance over the entire range of environmental conditions at a given site. (See “PV System Energy Performance Evaluations,” SolarPro, October/November 2014.)

To standardize performance evaluation activities, the IECRE includes an operational document, OD-402, regarding annual PV plant performance certification. This document defines terms—such as expected energy or energy performance index—that are essential for calculating plant performance. To facilitate feedback and learning, the test results are quantitative rather than merely pass or fail. The assessment accounts for nonoperational periods outside the control of plant operators, such as grid outages. It also compares actual O&M costs with the planned O&M costs and documents performance lost due to maintenance events. This feedback facilitates continual improvement.

Certifications in development. The list of operating documents in draft form or under development covers everything from project design to O&M.

Project design. A project design certificate, OD-403, is in draft form. This operational document will evaluate system designs against best practices for inverter and wire sizing, plant layout, shade analyses and climate- or region-specific considerations. 

Project condition. A project condition certificate, OD-404, also in draft form, will address considerations related to asset transfer. This operational document will evaluate the repair and maintenance needs of fielded plants and use historical performance to estimate degradation rates and quantify risk and value. The project condition evaluation will also include a field survey to identify hot spots, browning, etching, corrosion, damaged interconnects, delamination and other issues that can impact performance and lifetime. This type of condition assessment could prove useful after an extreme weather event as a means of identifying weather-related damages.

O&M. A review is under way for an O&M certificate, OD-410, which will provide a quality management system for O&M companies. When complete, this operational document will certify that providers have the training and the tracking systems in place to comply with technical specifications such as IEC 63049 and IEC 62446-2, which covers grid-connected PV system maintenance. This certificate will address common maintenance issues such as vegetative shading between rows in PV farms. On sites where O&M providers need to mow weeds, they must avoid flinging rocks into module glass or backsheets in the process. Service providers need to protect against damage inflicted by people or animals as well. In addition, the O&M certificate will include standards related to cleaning and soiling. For example, a report in the IEEE Journal of Photovoltaics (vol. 6, issue 5, pp. 1,333–38) suggests that some methods of squeegee-cleaning operating arrays may permanently damage monolithic thin-film modules due to partial shading patterns. The new O&M operating document will ensure that cleaning methods do not damage modules. It will also provide guidelines for conducting cost-benefit analyses to optimize the timing of these activities.

Future opportunities. Other opportunities lie ahead to develop and implement additional certifications. In 2018, for example, the IEC expects to publish new standards for inverters and power conversion equipment that include guidelines for robust product designs and quality management systems. Once the IEC publishes this technical standard, IECRE working groups can develop an associated certification for inverters.

Status of Implementation

To date, 16 countries have joined the IECRE, including Austria, Canada, China, Denmark, Egypt, France, Germany, Hungary, India, Japan, Netherlands, South Korea, Spain, United Arab Emirates, United Kingdom and the US. These countries are the member bodies of the IECRE, each represented with a national committee. Rules of participation vary from country to country. In the US, the national committee members are organizations—companies, labs and agencies—that participate in renewable energy industries; each organization designates one or more individuals to represent it.

Numerous organizations have applied for authorization to participate in the IECRE, including certification bodies, inspection bodies and test labs. The IEC is in the process of approving more than two dozen applications. Some requests for proposals now ask for IECRE certification. Large-scale PV installations are likely to utilize the IECRE certification process first, with eventual adaptation at the individual consumer level.

—Katherine Jordan / Complex Review / Denver / complexreview.com

—George Kelly / American Renewable Energy Standards and Certification Association / Norwich, VT / aresca.us

—Sarah Kurtz / National Renewable Energy Laboratory / Golden, CO / nrel.gov

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