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@ARTICLE{Wittmann:1029115,
      author       = {Wittmann, Ernst and Buerhop-Lutz, Claudia and Christlein,
                      Vincent and Hauch, Jens and Brabec, Christoph and Peters,
                      Ian Marius},
      title        = {{T}he {V}oltage-{E}ar – {A}n {A}nomaly in photovoltaic
                      systems with undersized inverters},
      journal      = {IEEE photonics journal},
      volume       = {16},
      number       = {4},
      issn         = {1943-0655},
      address      = {New York, NY},
      publisher    = {IEEE},
      reportid     = {FZJ-2024-04971},
      pages        = {1 - 6},
      year         = {2024},
      abstract     = {This study presents a phenomenon in photovoltaic field
                      installations we call voltage ear. PV installations exhibit
                      the voltage ear under specific conditions where modules
                      generate more power than the inverter can handle. When
                      inverters exceed their power limit it results in inverter
                      clipping, and the solar modules are regulated to operate at
                      a voltage above that at maximum power. This kind of voltage
                      rise leads to a specific pattern in the monitoring data –
                      the voltage ear. In the present study, data from a solar
                      park in France was analyzed. This park featured a high rate
                      of inverter malfunctions, including overheating and fires,
                      resulting in an estimated $5\%$ failure rate and,
                      ultimately, in a complete replacement of inverters. An
                      automated analysis of the monitoring data revealed 32.000
                      occurrences of excess voltage in 1.65 million data points
                      $(2\%).$ Instances of the phenomena were detected and
                      segmented using a K-means sorting algorithm, which yielded a
                      perfect recall value. Analysis of the identified voltage ear
                      conditions showed, that it occurs predominantly during
                      seasons of high irradiance and cool temperatures. Excess
                      voltages of up to 161 V in single strings were observed,
                      increasing the probability for PID and inverter damage. The
                      direct yield loss due to deviation from maximum power point
                      was between $0.02\%$ in January and $0.9\%$ in June. We
                      assume, that the voltage ear is a symptom of system design
                      issues that can result in malfunctioning of inverters and
                      hope that it will be useful as an indicator for identifying
                      design and operation issues.},
      cin          = {IEK-11 / IET-2},
      ddc          = {620},
      cid          = {I:(DE-Juel1)IEK-11-20140314 / I:(DE-Juel1)IET-2-20140314},
      pnm          = {1214 - Modules, stability, performance and specific
                      applications (POF4-121)},
      pid          = {G:(DE-HGF)POF4-1214},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:001283252600003},
      doi          = {10.1109/JPHOT.2024.3430029},
      url          = {https://juser.fz-juelich.de/record/1029115},
}