Strong Attraction and Adhesion Forces of Dust Particles by System Voltages of Photovoltaic Modules

Chun Sheng Jiang, Helio Moutinho, Bobby To, Chuanxiao Xiao, Craig Perkins, Matthew Muller, Mowafak Al-Jassim, Lin Simpson

Research output: Contribution to journalArticlepeer-review

15 Scopus Citations


We report for the first time on direct measurements using atomic force microscopy (AFM) of electric field induced attraction and adhesion forces associated with soiling on photovoltaic (PV) modules. Real dust particles and silica spheres as surrogate to simulating dust particles were glued to AFM probe cantilevers. The electric field induced force (Fes) was measured via AFM force-distance (f-z) curves, where the electric field was generated by applying a voltage (Vs) to a simulated PV module. Fes and van der Waals (Fvw) force contributions could be separated with the f-z curves. The results show that Fes ∼2.5 μN on dust particles is ∼5 times larger than Fvw ∼0.5 μN at even Vs = -100 V (i.e., similar to large-module operating voltages). Fes increases by an order of magnitude as the applied potential increases from Vs = -100 V to Vs = -500 V. These adhesion forces are by far the strongest that we have measured using the AFM technique for 'initial' contact of particles. Furthermore, unlike the more typical short-range forces of Fvw and liquid bridge, Fes extends sub-millimeters to a millimeter beyond the PV module surface, creating large attraction forces to even uncharged dust particles (i.e., via induced dipoles) in the air. These results indicate that the high voltages typically used with PV arrays today will attract more dust particles from the air, hold the dust particles to the surface very strongly, and potentially induce other PV module surface effects, all of which could increase the power production losses because of soiling.

Original languageAmerican English
Article number8727418
Pages (from-to)1121-1127
Number of pages7
JournalIEEE Journal of Photovoltaics
Issue number4
StatePublished - Jul 2019

Bibliographical note

Publisher Copyright:
© 2019 IEEE.

NREL Publication Number

  • NREL/JA-5K00-70821


  • Adhesion force
  • atomic force microscopy (AFM)
  • electric field
  • electric field attraction
  • electrostatic
  • photovoltaic (PV)
  • soiling
  • system voltage


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