Explain Staebler-Wronski Effect?

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  • Amorphous silicon cells degrade through a process called the Staebler-Wronski Effect. 
  • This degradation can cause reductions of 10-30% in the power output of the module in the first six months of exposure to light. Thereafter, the degradation stabilises and continues at a much slower rate.
  • The performance of the modules may tend to recover during the summer months, and drop again in the colder winter months


  • Additional degradation for both amorphous and crystalline technologies occurs at the module level and may be caused by:
  • Effect of the environment on the surface of the module (for example pollution).
  • Discoloration or haze of the encapsulant or glass.
  • Lamination defects.
  • Mechanical stress and humidity on the contacts.
  • Cell contact breakdown.
  • Wiring degradation.

2 Responses to "Explain Staebler-Wronski Effect?"
  1. Ravi Kiran P says:

    1. Are there any methods to decrease the degradation rate of the cells such as varying the doping percentage or material in the cells?
    2. Is the degradation rate high in tech such as concentrated photo voltaic tech wherein the electricity is generated at higher temp?

    • Module degradation is due to EVA (Ethyle Vynile Asitate) property. EVA is used for incapsulation of solar cells between the tedlar and the glass. Better EVA quality can reduce the modu,e degradation rate. Module is generally harmetically sealed, however some moisture can enter inside the module due to the thermal cycling when it is exposed to the varying weather conditions.
      The temperature alone do not have a major effect on the module degradation, it is the thermal cycling which affect the module property.

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