Comparison of Bifacial Solar Irradiance Model Predictions With Field Validation

Silvana Ayala Pelaez, Chris Deline, Sara M. Macalpine, Bill Marion, Joshua S. Stein, Raymond K. Kostuk

Research output: Contribution to journalArticlepeer-review

85 Scopus Citations


Models predicting rear irradiance for bifacial systems are critical to establish accurate estimates of energy yield. Here, we compare five published bifacial irradiance models, varying clearance, row spacing, tilt, and albedo to measure the sensitivity to these parameters. Bifacial energy gains (BGE) as high as 20% are predicted for some configurations. Model agreement is generally good for low ground clearance (clearance heights lower than 0.75 times the collector width), but at higher clearances, finite system size and edge effects become a significant factor in simulations, stretching assumptions of infinite system extent made in some models. In addition, rear irradiance uniformity is improved at high ground clearance, as expected. A test-bed construction and results are described for comparison between modeled and measured data in Golden, CO, USA. The investigations indicate that model agreement for BGE calculation is better than 2% (absolute) when compared with measured results, depending on the system configuration.

Original languageAmerican English
Article number8534404
Pages (from-to)82-88
Number of pages7
JournalIEEE Journal of Photovoltaics
Issue number1
StatePublished - Jan 2019

Bibliographical note

Publisher Copyright:
© 2011-2012 IEEE.

NREL Publication Number

  • NREL/JA-5K00-72510


  • Bifacial solar panels
  • irradiance modeling
  • photovoltaic (PV) system modeling


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