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Degradation Pathways in Glass/Glass Bifacial PV With Emerging Encapsulants and Half-Cut Cells

DuraMAT will combine accelerated stress testing, outdoor characterization, and microscopy/chemical failure analysis to understand packaging materials' degradation for bifacial and half-cell photovoltaic (PV) modules.

For mechanisms specific to these emerging module designs, we will pay particular attention to:

  • New encapsulant chemistries in bifacial glass/glass (G/G) structures
  • Potential for improved durability in half-cell modules with lower resistive power dissipation at interconnect regions.

Two ways to increase PV power generation per area are:

  • Bifacial PV, which can generate 10%–30% higher power compared to monofacial
  • Half-cell modules, which decrease cell-to-module losses by lessening resistive power dissipation.

While deployment of both technologies is rapidly growing, there is a lag in fundamental understanding of the new module packaging requirements and degradation processes.

Core Objective

Fielded Module Forensics


National Renewable Energy Laboratory


Our work is of immediate importance to PV experts in module manufacturing, field operation/ monitoring, and module qualification. Insights on durability of G/G packaging materials and half- versus full-cell designs will help de-risk the path to high energy density module architectures. Our methods for multiscale analysis, outdoor characterization, and accelerated stress testing will further serve as an important example for carrying out root cause failure analysis on new PV module designs.


This capability is available to NREL and external collaborators.


Sulas-Kern, D.B.; Owen-Bellini, M.; Ndione, P.; Spinella, L.; Sinha, A.; Uličná, S.; Johnston, S.; Schelhas, L.T. "Electrochemical Degradation Modes in Bifacial PERC Silicon Photovoltaic Modules," under review, 2021.

Sinha, A.; Sulas-Kern, D.B.; Owen-Bellini, M.; Spinella, L.; Uličná, S.; Pelaez, S.A.; Johnston, S.; Schelhas, L.T. "Glass/Glass Photovoltaic Module Reliability and Degradation: A Review" J. Phys. D: Appl. Phys. 2021, 54, 413002.

Johnston, S.; Moutinho, H.R.; Jiang, C.S.; Guthrey, H.L.; Norman, A.; Harvey, S.B.; Hacke, P.L.; Xiao, C.; Moseley, J.; Sulas, D.; Liu, J.; Albin, D.S.; Nardone, M.; Al-Jassim, M.A. From Modules to Atoms: Techniques and Characterization for Identifying and Understanding Device-Level Photovoltaic Degradation Mechanisms, OSTI Technical Report , 2019.


To learn more about this capability, contact Dana Kern.