The Effect of Inverter Loading Ratio on Energy Estimate Bias: Preprint

Kevin Anderson, William Hobbs, William Holmgren, Kirsten Perry, Mark Mikofski, Rounak Kharait

Research output: Contribution to conferencePaper


Subhourly effects, particularly variability in solar irradiance, can lead to underestimation of inverter clipping losses and overestimation of energy in hourly photovoltaic system performance models, particularly for systems with high inverter loading ratios. Direct simulation of this error can be complicated by factors such as the representation of spatial and temporal variability in hourly weather data and transient system conditions. In this work we take an alternative approach using real system power measurements to show that energy predictions from typical industry models suffer from a bias that increases with inverter loading ratio. We also show that this loading ratio-dependent bias is strongly correlated with an empirical subhourly inverter clipping bias derived from real power plant data. Finally, we show that this bias is not necessarily specific to any one model or weather dataset by recreating similar biases with alternatives of each.
Original languageAmerican English
Number of pages10
StatePublished - 2022
Event49th IEEE Photovoltaic Specialists Conference (PVSC 49) - Philadelphia, Pennsylvania
Duration: 5 Jun 202210 Jun 2022


Conference49th IEEE Photovoltaic Specialists Conference (PVSC 49)
CityPhiladelphia, Pennsylvania

NREL Publication Number

  • NREL/CP-5K00-82812


  • clipping
  • high-frequency
  • inverter
  • irradiance
  • modeling
  • photovoltaic
  • subhourly
  • variability


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