Wind speed and rear glass breakage on bifacial PV modules mounted on trackers
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Reports of glass breakage in bifacial PV modules installed in single-axis tracker-based solar farms have increased in recent years. While initial attention on tracker module failures was on 2P trackers due to torsional galloping, since 2020 there has been a growing body of reports for rear glass breakages afflicting solar farms installed with 1P tracker designs and large format (≥2.5m2) bifacial glass/glass modules supported on its long edges by short mounts. Importantly, such breakages occur in the absence of high wind speed events that could have explained the module breakages based on the module manufacturer's design wind load on approved module mounting design with short (usually 400-450mm in length) mounts on such tracker designs. This represents an existing engineering knowledge gap. While many hypothetical explanations were offered, there has been little clear evidence to further steer the attention towards any of the hypotheses.
In this white paper, DNV analyzes incidents where over 15% of bifacial PV modules on 1P trackers across the solar farm have experienced rear glass breakages. Additionally, mid-level wind speeds (>10m/s) were found to correlate well with glass breakages, both spatially across the solar farm and chronologically in relation to certain infield O&M events that are directly related to or can be related to glass breakages, which suggests that glass breakages were influenced by mid-level wind speed events.
This is the first report that analyses such correlation between module breakages and onsite records.
This paper was first published and presented at the 52nd IEEE Photovoltaic Specialist Conference in Seattle, USA, 9-14 June 2024.