Abstract—Soiling significantly reduces the energy production
of photovoltaic (PV) modules. The reduction is not only
determined by the amount and composition, but also by the size
distribution of the particles. This study investigates the
particle-size characteristics of dust accumulated on horizontal
and inclined glass surfaces used in PV modules. The
accumulated dust is compared to the ambient airborne dust.
Effects of tilt angle and wind speed are investigated. Variations
in particle size over the glass surface are also studied. Dust
accumulating on a photovoltaic module is finer than ambient
airborne dust, except for a combination of forward tilt AND low
wind velocity. For wind velocities large enough to initiate wind
erosion the accumulated dust is finer than the airborne dust
even in the case of forward tilt. For backward tilt the
accumulated dust is always finer than the airborne dust.
Reasons for the finer dust are the preferential accumulation of
the finer particles in the wake of the module due to their lower
response time compared to coarse particles and the preferential
removal of the coarsest fractions by the wind. At forward tilt
accumulated dust is finest near the leading and trailing edges of
a module whereas at backward tilt the particle size distribution
over a PV module is more uniform. Energy prediction models
should incorporate these internal variations and the differences
with airborne dust.
Index Terms—Dust, glass, particle size distribution, PV
module, soiling.
Dirk Goossens is with the Department of Electrical Engineering and the
Department of Earth and Environmental Sciences at KU Leuven, Belgium
(e-mail: dirk.goossens@kuleuven.be).
[PDF]
Cite:Dirk Goossens, "Soiling of Photovoltaic Modules: Size Characterization of the Accumulated Dust," Journal of Clean Energy Technologies vol. 7, no. 3, pp. 25-31, 2019.
