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PV Module Reliability Workshop Cultivates Innovation, Progress

March 15, 2011

On February 16 and 17, the PV Module Reliability Workshop upheld its reputation as a highly regarded event within the photovoltaics (PV) industry. This gathering of about 180 PV experts from the business and research communities provided a forum in which to exchange information. The event was sponsored by the Performance and Reliability Group within the National Center for Photovoltaics, based at the National Renewable Energy Laboratory (NREL).

NREL holds this series of workshops following the principle that there is great value in sharing information about module materials, tests, measurements, designs, and practices. Such an exchange of information lowers costs, improves PV module durability, and increases confidence in reliability.

The workshop is participatory in nature, so each attending organization was required to bring a presentation or posters. Typically, many of the presenters are key decision makers for module materials, design, and manufacturing in the most important multinational and domestic PV companies, testing labs, materials manufacturers, and the research community. About 180 people attended.(See the attendee and presentation lists on the workshop website.)

An excellent overview of the state of module durability was given by Dave Degraaff of SunPower, a vertically integrated PV company. First Solar discussed ongoing module durability and performance research themes of value to them—themes often pursued at NREL—and Amonix discussed the durability models and value proposition for concentrating photovoltaics (CPV). Plenary presentations and discussions to hear the customer's perspective were held with officers of Solar Power Partners and Borrego Solar Systems. Key themes included the need for industry-wide comparative metrics and tests for durability, and better understanding of location-dependent stresses that modules face—two areas where the NREL Performance & Reliability group leads in research and standards development.

Other parts of the workshop were more tutorial in nature. NREL's Keith Emery and Dirk Jordan described instrumentation and data analysis for determining PV system performance. Presenters also gave updates on the current knowledge of materials, such as glass for PV, and components, such as connectors. Other presentations described progress in harmonizing international standards and delineated areas in the standards arena where work is still needed.

Second-day, technology-specific sessions included timely themes in the major PV technologies.In crystalline silicon, presentations and discussions centered around modeling and quantifying power loss caused by cell cracks, the long-term effects of high-voltage system stress on modules, and the issue of how small breaks in the wire bussing in modules or connectors lead to arcing, and in some cases, fires.

In the thin-film area, the emerging subject of flexible barrier packaging and edge seals for active layers such as copper indium gallium diselenide (CIGS) was a main theme. In addition, the durability requirements for building-integrated photovoltaics (BIPV) and understanding the metastabilities in power of thin-film modules were presented and discussed.

In the CPV area, analyses of incumbent and emerging lens materials were presented, as were analyses of the degradation modes experienced by CPV. Another presentation featured discussions about the standard spectrum for use in rating CPV performance.

In the spirit of the workshop goals, participants shared a great deal of information, concerns, and progress updates. Many discussions addressed the challenges that the industry faces in common, such as bankability and the need for cooperation on developing industry-wide standards for materials, components, and module durability.

For more information about attendees and topics, see the 2011 PV Module Reliability Workshop website.