A Practical Irradiance Model for Bifacial PV Modules

William Marion, Christopher Deline, Amir Asgharzadeh, Fatima Toor, Daniel Riley, Joshua Stein, Clifford Hansen

Research output: NRELPresentation


A model, suitable for a row or multiple rows of photovoltaic (PV) modules, is presented for estimating the backside irradiance for bifacial PV modules. The model, which includes the effects of shading by the PV rows, is based on the use of configuration factors to determine the fraction of a source of irradiance that is received by the backside of the PV module. Backside irradiances are modeled along the sloped height of the PV module, but assumed not to vary along the length of the PV row. The backside irradiances are corrected for angle-of-incidence losses and may be added to the front side irradiance to determine the total irradiance resource for the PV cell. Model results are compared with the measured backside irradiances for NREL and Sandia PV systems, and with results when using ray tracing software.
Original languageAmerican English
Number of pages15
StatePublished - 2017

Publication series

NamePresented at the 44th IEEE Photovoltaic Specialist Conference, 25-30 June 2017, Washington, D.C.

NREL Publication Number

  • NREL/PR-5J00-68678


  • bifacial PV module
  • configuration factor
  • irradiance
  • model
  • performance


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