pv magazine Quality Roundtable, Taiwan: Carrier-induced solar cell degradation: Solved (sort of)

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Solar PV industry insiders discussed LID and floating panels at the pv magazine Quality Roundtable, held during Energy Taiwan 2018, last week.

Light-induced degradation (LID) is caused by boron-oxygen defects in the wafer material, while elevated temperature degradation (LeTID) is believed to involve excess hydrogen bonding with other chemical species. It is an ongoing discussion how to handle these effects.

Brett Hallam, a researcher at the University of New South Wales (UNSW) Sydney in Australia who studies defect-engineering, told pv magazine that for single crystal cells, most Chinese manufacturers use current injection to counteract the effects of both. As it does not depend on whether one generates carriers electrically or by illumination, the term carrier induced degradation might be even more accurate than the term light induced degradation.

At the seminar, however, Sascha Rossmann, VP of Global Sales for solar module manufacturer, Winaico, said that no solar cell manufacturers could reliably produce cells with less than 3.5% efficiency loss. Three percent losses are normally included in the warranty conditions. Machinery suppliers at the roundtable, such as Rehm Thermal Systems, added, that it would be possible to limit the loss to about 2%. The discrepancy between the 2% and 3.5%, however, can be due to other limitations in mass production, such as differences in materials or production lines.

Some, such as the executive director of EPC Sinogreenergy, K.H. Chen, believe that if the volume of purchased modules is high enough and they degrade, then module manufacturers should immediately replace degraded products without waiting for third party analyses to find the root cause. Others, such as a vice general manager at TÜV Rheinland, Sebastian Petreschek, said that it is too much of a burden.

Other topics discussed during the quality roundtable included how to use machine learning algorithms to spot problems with rooftop solar modules, and some of the issues with floating PV systems, which come in handy when there is not enough space available.

Xiao Fuqin, vice general manager of inverter-manufacturer Sungrow’s 2016-born floating panel branch, said they are faster to build and deliver more power output than other solar farm types, but it is challenging to ensure they can last for up to 25 years. Hongjie Hu, a market development manager at DuPont, pointed out that panel frames or edges eroding from water is one such threat.

This was the 12th pv magazine Quality Roundtable worldwide, and the second in Taiwan. The event, with about 100 attendees, was organized by pv magazine in collaboration with SEMI and PV Guider, and initiative partner DuPont. Further sponsors were Sungrow, Stäubli, TÜV Rheinland, Winaico and Rehm Thermal Systems.

Read about the discussions at the Quality Roundtable and Future PV Roundtable, held last week in India at REI 2018, and watch out for coverage from pv magazine Roundtables at SPI in the United States this week, and All Energy Australia, next week. The video from our first Latin American Quality Roundtable is also available to view now.

By Andrew Silver