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SESK: Stuff Everyone Should Know · sesk.info/solar-uneven-dirt-hot-spots

Besides cutting output, what problem can uneven dirt like bird droppings cause on solar panels?

Localized hot spots.

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  3. Localized hot spots ✔

Why: When part of a panel is covered, that spot can heat up instead of making power. NREL says to reduce uneven soiling, such as bird droppings.

Huh, didn't know that: NREL notes a heavy rain can clean an array for free, which makes cleaning benefits hard to calculate.

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References

Answer: Localized hot spots. When part of a panel is covered, that spot can heat up instead of making power. NREL says to reduce uneven soiling, such as bird droppings.

  1. NREL: Best Practices for O&M of PV and Energy Storage Systems, 3rd ed. (2018) docs.nlr.gov/docs/fy19osti/73822.pdf
    Soiling reduces the energy output of the PV array and can lead to localized hot-spot failures if the soiling is uneven.
    Checked 2026-10-10.

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