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Balance of System and Power Electronics Testing: Task Group 11

Task Group 11’s system verification work aims to develop a comprehensive system for certification of photovoltaic (PV) systems and components, including verifying appropriate design, installation, and operation methods.

Task Group 11 has recently focused mainly on power conversion electronics (PCE), with focus on PV inverters. The interests of the participants (largely manufacturers, test labs, and product customers) have defined the subgroup’s scope:

  • Elucidating failure mechanisms at the materials science level

  • Cataloging results from the field to understand the stresses under which devices fail

  • Designing appropriate tests for specific failure mechanisms seen in the field because the stresses and levels in current IEC tests for balance-of-system (BOS) components are regarded as not having sufficient physical basis and are not currently employed by solar BOS manufacturers

  • Comparing and contrasting test protocols in existence. While design verification and validation tests are usually the manufacturer’s domain, consensus is lacking on third-party verification tests (e.g., IEC, TUV-Rheinland 2PfG reliability and safety standards of AC/DC components, Sunspec 4C, materials durability, insulation, communication protocols, etc.).

  • Collecting data and information from related products that can clarify the durability of PV electronics products

  • Developing ways to visualize the durability data of PV electronics products, including in standards, accelerated stress tests, and field results

  • Developing pointers to design for reliability, including elucidating what is known about the most important failure modes

  • Understanding causes of nuisance trips (including earth fault) and coordinating mismatched standards to minimize them

  • Determining how to test components (e.g., boards, subsystems) and conditions for certification of that board within various larger systems, including for qual testing

  • Determining the potential wear-out mechanisms; i.e., what is limiting the warranty term and elucidating areas for improvement to extend life

  • Developing quality assurance programs, including collection of data to elucidate failure points in the production, delivery, installation, and operations and maintenance; and identifying areas for continuous improvement in the value chains for devices

  • Developing useful standards for stakeholders

  • Developing and validating analytical models and tools to assist with failure analysis, e.g., thermal, electrical, humidity, and combined models. Looking at the most critical components, the idea is to answer what the useful tests are: component-based (e.g., IPC, telcordia) and environment-based.

  • Developing of tools and models to study the consequences of failures, including performance and safety. Those tools could help evaluate the relative priority for different failure (failure mode and effects analysis).

Complementary efforts are underway to support module durability and manufacturing consistency.

Progress Update

Task Group 11 has been examining failure mechanisms at the materials science level. This examination includes the development and validation of analytical models and tools (e.g., thermal, electrical, humidity, and combined models). The models help establish meaningful accelerated lifetime tests for power conversion electronics, which can be incorporated into useful standards for stakeholders.

The special focus is on the development of IEC 62093 ED2: “Power conversion equipment for photovoltaic systems - Design qualification testing.”

Standards Activities

IEC 62093 ED2: Power conversion equipment for photovoltaic systems - Design qualification testing

Related Resources

Hacke, P., Lokanath, S., Williams, P., Vasan, A., Sochor, P., Tamizh Mani, G., Shinohara, H., and Kurtz, S, A Status Review of Photovoltaic Power Conversion Equipment Reliability, Safety, and Quality Assurance Protocols, Renewable and Sustainable Energy Reviews

Chung HS, Wang H, Blaabjerg F, Pecht M, editors. Reliability of power electronic converter systems. Institution of Engineering and Technology (IET); 2015

PVQAT Task Group 11 Failure Modes, Mechanisms, and Effects Analysis for Inverter components accessed 30 June 2020 (use for request of password)

Task Leaders

Peter Hacke, National Renewable Energy Laboratory, coordinating the subgroup on power electronics

Other leaders are welcome.