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PV Module-Level Solutions for Degradation by Ionization Damage

DuraMAT will test the susceptibility of various photovoltaic (PV) cell types under the ionizing stress of ultraviolet light and positive electric potential. Then, we can identify the properties of module packaging materials required to mitigate power degradation.

We will quantify an examination of the relationship between material properties, such as resistivity and ultraviolet cut-off wavelength. With this, we will inform the PV module value chain and how to appropriately value materials and to minimize degradation rates for a 50-year module life.

PV modules are subjected to ultraviolet light and electrochemical potential gradients continuously during their operation.  These stress factors cause ionization and chemical changes in the cell and module.  Also, because higher-efficiency PV cells rely on excellent surface passivation, susceptibility to ionization damage is becoming a greater factor in power loss. Candidate mechanisms for this include:

  • Loss of hydrogen providing surface passivation at the cell front
  • Degradation of the optics in the surface passivation layer and the encapsulant
  • Formation and migration of ions, resulting in chemical reactions
  • Changes in interface and fixed charge states at the cell surface.

Core Objective

Disruptive Acceleration Science


National Renewable Energy Laboratory and SLAC National Accelerator Laboratory


  • Testing of solar cells to ionizing ultraviolet light and voltage potential
  • Evaluation of module encapsulation material to prevent power loss by ionization processes
  • Evaluation of products of degradation for identification of the mechanisms.


Available to NREL scientists and external collaborators


Bosco, N.; Moffitt, S.; Schelhas, L.T. (2019) “Mechanisms of adhesion degradation at the photovoltaic module's cell metallization‐encapsulant interface.” Progress in Photovoltaics: Research and Applications, 27 (4), 340-345. 
Hacke, P.; Miller, D. C.; Moffitt, S.; Sinha, A.; Schelhas, L. T. (2019) “Module-Level Solutions for Degradation by Ionization Damage.” Proceedings of the 2019 PV Reliability Workshop, 26-38 February, Lakewood, CO, p. 842. 
Li, J.; Shen, Y.C.; Hacke, P.; Kempe M. (2018)  “Electrochemical mechanisms of leakage-current-enhanced delamination and corrosion in Si photovoltaic modules.” Solar Energy Materials and Solar Cells, 188, 273-9.  
Hacke, P.; Terwilliger K.; Glick S.; Smith R.; Perrin G.; Kurtz S.; Bosco N.; Wohlgemuth J. (2014)  
"Application of the terrestrial photovoltaic module accelerated test-to-failure protocol." In 2014 IEEE 40th Photovoltaic Specialist Conference (PVSC), pp. 0930-0936. 


To learn more about module-level solutions for degradation by ionization damage, contact Peter Hacke.

Two images of modules showing the frame, glass, EVA, and backsheet. One image is labeled UV radiation showing hydrogen loss at cell/passivation interface, hot carrier damage and interface bulk defects,  EVA discoloration and delamination, and backsheet yellowing. The other image is labeled electrical field showing oxidation and sulfurization of Ag gridlines, Age ion transport from cell to EVA, and ARC degradation (delamination,discoloration).

UV radiation and electric field ionization mechanisms that degrade PV modules.