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effect of dust on the performance of solar PV panel

Discussion in 'Mathematics and Physics' started by PG1995, Apr 10, 2015.

  1. PG1995

    PG1995 Active Member

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    Hi

    I was having a discussion with someone and that someone was of the opinion that solar panels shouldn't be used in countries where dust is prevalent assuming no manual cleaning or self-cleaning method is used. It seems plausible that dust or any other impurity accumulated on the panel itself or too much dust in the environment would affect the efficiency of panels.

    A monocrystalline panel is optimistically 25% efficient. It means that average insolation of 1000 W/m^2 would produce 250W. I googled to get some estimate about how much efficiency is affected due to dust etc. This webpage says, "That loss may range as high as 25% in some areas according to the National Renewable Energy laboratory. Individual dealers have reported losses as high as 30% for some customers who failed to ever clean their panels". I have also been through two papers [3] and [4] but couldn't get any clear estimate. According to [4], the efficiency is greatly affected by dust.

    Thank you for your help.

    Regards
    PG

    References and helpful links:
    1: http://www.solar-facts-and-advice.com/solar-energy.html
    2: http://www.solar-facts-and-advice.com/solar-panel-cleaning.html
    3: http://www.academia.edu/4117648/Eff...oltaic_Performance_Review_and_Research_Status
    4: http://www.academia.edu/3037876/Effect_Of_Dust_On_The_Performance_Of_Solar_PV_Panel
     
  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Are there any countries where dust isn't prevalent? :).
    Dust might well account for 25% or much greater loss of efficiency if allowed to remain on the panels. However, the orientation (slope) of the panels and their degree of exposure to wind and rain will be factors affecting how much dust remains and hence the average efficiency.
     
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  3. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    It is true that reports of dust accumulation can attenuate PV up to 90% and other reports that a HV electrostatic Field can repel up to 90% of the dust after cleaning... in the absence of rain.

    "A single-phase high voltage is applied to parallel wire electrodes embedded in the cover glass plate of a solar panel. It has been demonstrated that more than 90% of the adhering sand is repelled from the surface of the slightly inclined panel after the cleaning operation. "
    Electrostatic cleaning system for removal of sand from solar panels
     
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  4. dave

    Dave New Member

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  5. PG1995

    PG1995 Active Member

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    Thank you.

    Could you please tell me where you get this "90%" figure from?

    Regards
    PG
     
  6. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    your ref #4. https://www.academia.edu/3037876/Effect_Of_Dust_On_The_Performance_Of_Solar_PV_Panel

    e.g.
    Fig 5
    0.6% max with dust
    Fig 6
    6 % without dust
    Thus ~ 10% of clean PV.

    Although if late afternoon > 2pm ratio drops due to sun angle on dust-free PV but Dust covered PV stays flatter and even improves at 1 PM when Solar power in Fig 3 dropped perhaps from slight overcast or smog.

    However writer concludes "the result shows that dust considerably reduces the power production by 92.11% and efficiency as 89%."


    ___________
    here "Even a little bit of dust, for example one-seventh of an ounce per square yard (= 4 grams / square meter) —can weaken a panel’s power conversion by 40%."

    But if you live in Cali....
    "Researchers found panels that hadn't been cleaned, or rained on, for 145 days during a summer drought in California, lost only 7.4 percent of their efficiency

    Read more at: http://phys.org/news/2013-07-solar-panels-worth.html#jCp"
     
    Last edited: Apr 12, 2015
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  7. PG1995

    PG1995 Active Member

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    Thank you.

    To me, the two sources mentioned by you are in a little bit of conflict.

    Source #1:
    "Even a little bit of dust, for example one-seventh of an ounce per square yard (= 4 grams / square meter) —can weaken a panel’s power conversion by 40%."

    Source #2:
    "Researchers found panels that hadn't been cleaned, or rained on, for 145 days during a summer drought in California, lost only 7.4 percent of their efficiency."

    I tried to find a figure on dust deposition in California without any success. "145 days" are more than four months but still efficiency was only reduces by 7.4 percent. On the other hand, Source #1 says that 4 grams/square meter can reduces efficiency by 40%. Why wasn't the efficiency affected that much in California over the period of 145 days? Should we just assume that there is dust in California?! Thanks.

    Regards
    PG
     
  8. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    You can't expect much consistency without a pollen and dust analysis. Nor can you expect crystalline dust to be a linear filter. Until regional averaged data is avail. with environmental factors such as wind , rain and height above the ground, it is rather limited in accuracy and statistical accuracy.

    I do think the electro-static repulsion with almost zero power is a good idea. It might even keep birds away.
     
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  9. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hello there,

    You can also think about this like your automobile windshield. It gets dirty but not that dirty unless you are driving in bad conditions.
    Here where i park, the windshield only gets a little dirty unless it is driven where there is road stuff that comes up onto the window. When parked the main stuff comes from the trees and occasional birdie droppings. The trees drop different things depending on what kind you have nearby. Mine drop seedlings and some leaves. The leaves usually blow off unless it rains first. The seedlings can stay put for several days unless we get a good wind, but they only cover probably 10 percent of the area of the whole windshield.
    Depending on the direction the car is parked, i can also get road dust on the windshield, but it's not real thick dust just very light. It's hard to estimate the optical drop in efficiency of the glass plus dust though, and it would vary by the amount of traffic that went by and other conditions like wind. I dont see this as something you can accurately estimate and be confident that the estimate will be good for all year round or even season to season or for all years in say a decade, just because it's like trying to predict the weather. I would say try to strive for a top limit and be satisfied with that.
     
    Last edited: Apr 19, 2015
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  10. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    Imagine how much pollution there is in other parts of the world.
     

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