Improvements to PVWatts for Fixed and One-Axis Tracking Systems: Preprint

Research output: Contribution to conferencePaper


This work presents improvements to the widely used NREL PVWatts photovoltaic system energy model to improve modeling accuracy for typical fixed and one axis system designs. The aim is to calculate losses in the PV system assuming typical modern system design assumptions, while maintaining simplicity by keeping the required set of input parameters small. These improvements allow users to more credibly and quickly evaluate competing system designs in early stage feasibility. Common submodels for module cover, spectral, snow, tracker, transformer, plant controller, and self-shading losses, in addition to a bifacial gain option, are incorporated into the PVWatts model, and are shown to improve PVWatts' system performance prediction capabilities without major impact to ease of use.
Original languageAmerican English
Number of pages9
StatePublished - 2019
Event46th IEEE Photovoltaic Specialists Conference (PVSC 46) - Chicago, Illinois
Duration: 16 Jun 201921 Jun 2019


Conference46th IEEE Photovoltaic Specialists Conference (PVSC 46)
CityChicago, Illinois

Bibliographical note

See NREL/CP-6A20-76289 for paper as published in IEEE proceedings

NREL Publication Number

  • NREL/CP-6A20-74097


  • bifacial
  • photovoltaic modeling
  • PVWatts
  • self-shading


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