Traditional AL-BSF PV cells are made to convert light hitting the front side of the cell to electricity. However newer PV cell designs (e.g., PERC, PERL, PERT, and HIT) with some minor modifications can be made so that light hitting from both sides contributes to the current produced by the cell. When placed into modules designed with transparent backsheets or glass-glass construction, bifacial PV modules are born. This idea is not new, but has only recently been applied to mainstream PV modules and systems and is growing fast.  ITRPV 2018 forecasts predict that bifacial modules will make up 10% of the world market share of PV modules by 2020 and over 30% by 2028.

Ask yourself, if the first PV cell that was invented was bifacial, how would PV modules and systems be different from today’s PV technologies?  We believe that bifacial PV represents a revolutionary opportunity for increasing the efficiency and lowering the cost of solar energy systems.  Field data, characterization methods and standards, and predictive models are needed.

Sandia National Laboratories, the National Renewable Energy Laboratory, and the University of Iowa worked together from 2016-2018 to better understand the performance characteristics of bifacial PV modules and systems. Sandia and NREL are currently working together on a follow-on project from 2019-2021 aimed at optimizing the performance of bifacial PV systems.

1. Outdoor bifacial PV performance data
2. Bifacial characterization and rating standards
3. Performance modeling of bifacial PV systems

Our Team:

• Joshua S. Stein   Sandia National Laboratories   (Principal Investigator; Field data and modeling)
  • Cameron Stark, Dan Riley, Cliff Hansen
• Chris Deline        National Renewable Energy Laboratory  (Co-PI; Characterization and modeling)
  • Silvana Ayala Pelaez, Bill Marion
• Fatima Toor        University of Iowa   (2016-2018)
  • Amir Asgharzadeh Shishavan (PhD, 2019)

Publications and Presentations

2021

• MESIA Webinar on Bifacial Photovoltaic Module and Systems: Experience and Results – Moderated by Joshua S. Stein, June 29, 2021: Recording: https://lnkd.in/dXA6SHB.
• Stein, J.S., C. Reise, et al. (2021). IEA-PVPS T13-14:2021: Bifacial Photovoltaic Modules and Systems: Experience and Results from International Research and Pilot Applications (1321 downloads)
• Pike, C., E. Whitney, M. Wilber and J. S. Stein (2021). “Field Performance of South-Facing and East-West Facing Bifacial Modules in the Arctic.” Energies 14(4): 1210.
• Marion, B., Measured and satellite-derived albedo data for estimating bifacial photovoltaic system performance, Solar Energy, v.215, pp. 321-327, 2021, https://doi.org/10.1016/j.solener.2020.12.050.

2020

• Monark, Mark and Ayala Pelaez, S., Analysis and Validation of Spectral Irradiance Simulations for 75 kW Bifacial Solar Test Field, NREL Student Intern Symposium, 2020
• Stein, J.S. et al., Estimation of Maximum Current Generated by Bifacial PV Arrays for System Design,”  EU PVSEC, 2020. SAND2020-9271C.
• Marion, B., “Albedo Data Sets for Bifacial PV Systems,” in 2020 IEEE 47^th PVSC, 2020.
• Gostein, M., Marion, B., Stueve, B., “Spectral Effects in Albedo and Rearside Irradiance Measurement for Bifacial Performance Estimation,” in 2020 IEEE 47^thPVSC, 2020.
• Ayala Pelaez, S., Deline, C., Marion, B., Sekulic, B., McDanold, B., Parker J., Stein, J.S. “Field-Array Benchmark of Commercial Bifaical PV Technologies with Publicly Available Data” 47th IEEE PVSC Conference, virtual June 2019.
• Carlos D. Rodríguez-Gallegos, Haohui Liu, Oktoviano Gandhi, Jai Prakash Singh, Vijay Krishnamurthy, Abhishek Kumar, Joshua S. Stein, Shitao Wang, Li Li, Thomas Reindl, Ian Marius Peters. Global Techno-Economic Performance of Bifacial and Tracking Photovoltaic Systems. Joule, 2020; DOI: 10.1016/j.joule.2020.05.005
• Cell Press. (2020, June 3). Double-sided solar panels that follow the sun prove most cost effective. ScienceDaily. Retrieved June 4, 2020
• Deline, C., S. A. Pelaez, S. MacAlpine and C. Olalla (2020). “Estimating and parameterizing mismatch power loss in bifacial photovoltaic systems.” Progress in Photovoltaics. https://doi.org/10.1002/pip.3259.
• Ayala Pelaez, S. and C. Deline (2020). “bifacial_radiance: a python package for modeling bifacial solar photovoltaic systems.” Journal of Open Source Software 5(50). https://doi.org/10.21105/joss.01865

2019

• Stein, J.S, M. Prilliman, C. Stark, J. Nagyvary, S. Ayala Pelaez, C. Deline, Bifacial Performance Optimization Studies using Bifacial Radiance and High Performance Computing (1069 downloads) , Presented in: 36^th EU PVSEC, Marseille France, Poster.
• Deline C, Ayala Pelaez S, MacAlpine S, Olalla C. Bifacial PV System Mismatch Loss Estimation & Parameterization. Presented in: 36^th EU PVSEC, Marseille France. Slides
• Bill Marion, “Albedo from satellite and ground-based observations”, 2019 BiFi PV Workshop, Amsterdam, Netherlands, September 16-17, 2019.
• Michael Woodhouse, Bill Marion, Susan Huang, David Feldman, Brittany Smith, and Robert Margolis, “Considerations for Utilizing Bifacial Photovoltaic Technologies Based Upon Their Impact to Project Financial Metrics”, 2019 BiFi PV Workshop, Amsterdam, Netherlands, September 16-17, 2019.
• Deline et al. 2019.  Bifacial PV System Performance: Separating Fact from Fiction (2042 downloads) , Plenary presentation at Photovoltaics Specialists Conference, Chicago, IL.
• Stein et al. 2019.  Bifacial Photovoltaic Performance Optimization Using Ray Tracing and High Performance Computing (1103 downloads) , Keynote presentation at Photonics North, Quebec City, Canada.
• Ayala Pelaez et al. 2019. The subtle art of bifacial performance modeling (2259 downloads) , 12th PV Performance Modeling Workshop, Albuquerque, NM.
• Marion, Bill, 2019.  Albedo Data to Facilitate Bifacial PV System Planning (1525 downloads) , 12th PV Performance Modeling Workshop, Albuquerque, NM.
• Marion B, Albedo Data for Bifacial PV Systems, PV Reliability Workshop, 2019
• Ayala Pelaez, S., C. Deline, P. Greenberg, J. S. Stein and R. K. Kostuk (2019). “Model and Validation of Single-Axis Tracking with Bifacial PV.” Journal of Photovoltaics, 9(3): 715-721.  DOI: 10.1109/JPHOTOV.2019.2892872.
• Liang, T. S., M. Pravettoni, C. Deline, J. S. Stein, R. Kopecek, J. P. Singh, W. Luo, Y. Wang, A. G. Aberle and Y. S. Khoo (2019). “A review of crystalline silicon bifacial photovoltaic performance characterisation and simulation.” Energy & Environmental Science 12(1): 116-148. DOI 10.1039/C8EE02184H.
• Ayala Pelaez, C. Deline, S. Macalpine, B. Marion, J. S. Stein, and R. K. Kostuk, “Comparison of bifacial solar irradiance model predictions with field validation,” IEEE J. Photovoltaics, vol. 9, no. 1, pp. 82–88, 2019. https://ieeexplore.ieee.org/abstract/document/8534404

2018

• Stein, J.S. and Jordan, D.C. 2018. Glass-Glass Photovoltaic Modules – Overview of Issues (1905 downloads) . DuraMAT Fall Workshop, Stanford, CA
• Hansen et al. 2018. Field Performance of Bifacial PV Modules and Systems (1660 downloads) . 28th NREL Silicon Workshop, Winter Park, CO.
• Riley, D. et al. 2018. Performance of Bifacial PV Modules with MLPE vs. String Inverters (1547 downloads) . WCPEC-7, Waikoloa, HI.
• Ayala Pelaez, S. 2018. Model and Validation of Single-Axis Tracking with Bifacial PV (1659 downloads) . WCPEC-7, Waikoloa, HI. (Paper submitted to JPV). Preprint: https://www.nrel.gov/docs/fy19osti/72039.pdf
• Asgharzadeh, A. 2018.  A Comparison Study of the Performance of South/North-facing vs East/West-facing Bifacial Modules under Shading Conditions (1419 downloads) . WCPEC-7, Waikoloa, HI.
• Ayala Pelaez, S. et al. 2018. Comparison of Bifacial Solar Irradiance Models with Field Validation (1812 downloads) . 10th PV Performance Modeling Collaborative Workshop, Albuquerque, NM
• Asgharzadeh, A. et al. 2018. Bifacial PV System Performance: Investigation of Shading Conditions (1723 downloads) . 10th PV Performance Modeling Collaborative Workshop, Albuquerque, NM
• Asgharzadeh, A. et al. 2018. “A Sensitivity Study of the Impact of Installation Parameters and System Configuration on the Performance of Bifacial PV Arrays.” IEEE Journal of Photovoltaics 8(3): 798-805.
• Stein, J.S., 2018. Solar PV Performance and New Technologies in Northern Latitude Regions (1523 downloads) . Alaska Rural Energy Conference, Fairbanks, AK.
• Hansen et al., 2018. Field Performance of Bifacial PV Modules and Systems (1466 downloads) . PV Module Technology & Applications Forum 2018, Cologne, Germany

2017

• Stein, J.S. et al., 2017. Comparison of modeling methods and tools for bifacial PV performance (2325 downloads) . 9th PV Performance Modeling and Monitoring Workshop, Weihai, China.
• Deline, C., et al., 2017. Bifacial PV Performance Models: Comparison and Field Results (2124 downloads) . BiFiPV 2017 Workshop, Konstanz, Germany
• Hansen, C., et al., 2017. A Detailed Performance Model for Bifacial PV Modules (1887 downloads) . 33rd European PV Solar Energy Conference and Exhibition. Amsterdam, Netherlands.
• Stein, J. S., et al., 2017. Outdoor Field Performance of Bifacial PV Modules and Systems (1723 downloads) . 33rd European PV Solar Energy Conference and Exhibition. Amsterdam, Netherlands.
• Asgharzadeh, A. et al., 2017. Analysis of the Impact of Installation Parameters and System Size on Bifacial Gain and Energy Yield of PV Systems (2085 downloads) . 44th IEEE PVSC. Washington, DC.
• Stein, J. S., et al., 2017. Outdoor Field Performance from Bifacial Photovoltaic Modules and Systems (1857 downloads) . 44th IEEE PVSC. Washington, DC. SAND2017-6464C.
• Hansen, C. W., et al., 2017,. A Detailed Model of Rear-Side Irradiance for Bifacial PV Modules (1661 downloads) . 44th IEEE PVSC. Washington DC. SAND2017-6554 C.
• Marion, B., et al., 2017. A Practical Irradiance Model for Bifacial PV Modules (2078 downloads) . 44th IEEE PVSC. Washington DC.
• Riley, D., et al., 2017. A Performance Model for Bifacial PV Modules (2002 downloads) . 44th IEEE PVSC. Washington, DC.
• Hansen and Riley, 2017, Performance model for bifacial PV modules (5947 downloads) . Presentation at the 8th PVPMC Workshop, Santa Ana Pueblo, New Mexico.
• Asgharzadeh, A., et al., 2017.  “Ray Tracing Models for Bifacial PV Performance“. Presentation at the 8th PVPMC Workshop, Santa Ana Pueblo, New Mexico.
• MacAlpine et al., 2017,”Progress Toward Efficient Bifacial Rear Irradiance Models”, Presentation at the 8th PVPMC Workshop, Santa Ana Pueblo, New Mexico.
• Deline, C., S. MacAlpine, B. Marion, F. Toor, A. Asgharzadeh and J. S. Stein (2017). “Assessment of Bifacial Photovoltaic Module Power Rating Methodologies – Inside and Out.” Journal of Photovoltaics,V. 7(2), p. 575-580.
• Stein et al., 2017, Field Performance of Bifacial PV Modules and Systems (7326 downloads) , Presentation at the 8th PVPMC Workshop, Santa Ana Pueblo, New Mexico.
• Stein, J.S., Burnham, L., and, Lave, M. 2017. One Year Performance Results for the Prism Solar Installation at the New Mexico Regional Test Center: Field Data from February 15, 2016 - February 14, 2017 (2224 downloads) . Albuquerque, NM, Sandia National Laboratories. SAND2017-5872.

2016

• Deline, C., S. MacAlpine, B. Marion, F. Toor, A. Asgharzadeh and J. S. Stein. 2016. Evaluation and Field Assessment of Bifacial Photovoltaic Module Power Rating Methodologies. 43rd IEEE Photovoltaic Specialist Conference. Portland, OR.
• Hansen, C. W., J. S. Stein, C. Deline, S. MacAlpine, B. Marion, A. Asgharzadeh and F. Toor.  2016. Analysis of Irradiance Models for Bifacial PV Modules (1568 downloads) . 43rd IEEE Photovoltaic Specialist Conference. Portland, Oregon. SAND2016-0803 C.

Bifacial Open Source Software

• bifacial_radiance: Contains a series of Python wrapper functions from NREL to make working with RADIANCE easier, particularly for the PV researcher interested in bifacial PV performance.
• bifacialvf: A self-contained view factor (or configuration factor) model from NREL which replicates a 5-row PV system of infinite extent perpendicular to the module rows. Single-axis tracking is supported, and hourly output files based on TMY inputs are saved. Spatial nonuniformity is reported, with multiple rear-facing irradiances collected on the back of each module row.
• 3Dbifacial_VF: Matlab functions and example scripts to model rearside irradiance using a 3D view factor approach.  Able to simulate variations across individual modules in an array.  Code is available here: Sandia_Bifacial-PV_View-Factor-code_0.2-1.zip (2968 downloads)

Bifacial Workshops (click on links to access information and presentations)

2019	2019 Bifacial (BiFi) Workshop	Amsterdam, Netherlands
2018	2018 Bifacial (BiFi) Workshop	Denver, USA
2017	2017 Bifacial (BiFi) Workshop	Konstanz, Germany
2016	2016 Bifacial (BiFi) Workshop	Miyazaki, Japan
2015	2015 Bifacial (BiFi) Workshop	Antofagasta, Chile
2014	2014 Bifacial (BiFi) Workshop	Chambery, France
2012	2012 Bifacial (BiFi) Workshop	Konstanz, Germany

 

External Bifacial Resources and References (please send me additional references to add to this site)

• New Energy Update Article that includes quotes from project members: “As US cuts tariffs, bifacial builders test design gains“, June 19, 2019
• Castillo-Aguilella, J. E. and P. S. Hauser (2016). “Multi-Variable Bifacial Photovoltaic Module Test Results and Best-Fit Annual Bifacial Energy Yield Model.” IEEE Access 4: 498-506.
• Anoma, M. A., D. Jacob, B. C. Bourne, J. A. Scholl, D. M. Riley and C. W. Hansen (2017). View Factor Model and Validation for Bifacial PV and Diffuse Shade on Single-Axis Trackers (1662 downloads) . 44th IEEE PVSC, Washington, DC.
• SolarWorld White Paper: “Calculating the Additional Energy Yield of Bifacial Solar Modules“