c1 drafted · lead Module front glass
Deposits cause optical losses by lowering the transmittance of the glazing.
- Assessment of Photovoltaic Module Failures in the Field
sec=4.2.2h=389a887eb5f2
Soiling Losses
Soiling losses happen when dust, dirt and other particles build up on the module glass. Less light gets through to the cells, so yield goes down. Production usually drops slowly during dry spells and comes back after rain or cleaning. The loss can vary a lot from one site to another. Uneven dirt, such as a band along the bottom row of cells, can trigger a bypass diode. This costs power even when short-circuit current hardly changes, so Isc readings alone can make the loss look smaller than it is. To confirm soiling, use a soiling station or clean and dirty reference sensors, and track performance ratio or weather-normalized output over several days. Visual inspection and IV curve tracing help show where the dirt is and how it changes the module's electrical behaviour. To reduce the loss, set cleaning schedules from the measured soiling rate and the cost of cleaning, and consider anti-soiling coatings or a different module tilt.
<!-- review notes
- sentence 3: support check: partial - Bypass-diode power loss without Isc change and Isc underestimation are stated, but the specific band along bottom row of cells as trigger is only loosely tied.
- sentence 4: support check: partial - Methods are listed, but 'over several days' is only from energy-ratio detection, not a general confirmation recommendation.
- sentence 5: support check: partial - Visual inspection is a listed method and IV curves show soiling effects, but passages don't state they show where dirt is or are used as detection. -->
Claims
affects
presents_as
c2 drafted · lead Gradual performance decline
The soiling ratio falls while deposits build up and recovers after rain or other cleaning events.
- pv model losses
sec=fronth=10001d881d82 - Soiling Losses – Impact on the Performance of Photovoltaic Power Plants
sec=3.1h=1bd67b0ecb1e
c3 drafted · lead Reduced short-circuit current
Uniform soiling lowers short-circuit current roughly in step with power output.
- Soiling Losses – Impact on the Performance of Photovoltaic Power Plants
sec=3.1h=1bd67b0ecb1e
c4 drafted · lead Bypassed substring
When dirt collects unevenly, for example along the bottom row of cells, the bypass diode can open a soiled cell string. Power is lost but short-circuit current does not change.
- Soiling Losses – Impact on the Performance of Photovoltaic Power Plants
sec=3.1h=1bd67b0ecb1e
review note: support check: partial - Bypass diode opening a soiled string gives power loss without Isc change, but the passage mentions bottom-row accumulation only from partial cleaning, not exactly this framing; mostly supported.
c5 drafted · lead Distorted IV curve shape
Non-uniform soiling changes the shape of the IV curve and lowers Isc and maximum power by different amounts.
- Soiling Losses – Impact on the Performance of Photovoltaic Power Plants
sec=3.1h=1bd67b0ecb1e - Guidelines for Operation and Maintenance of Photovoltaic Power Plants in Different Climates
fig=95h=64f5d28c60e3
detected_by
c6 drafted · lead Soiling station
IEC 61724-1 calls for an on-site soiling station to reach monitoring class A.
- soiling losses
sec=h7h=22baf3f6fdbf - soiling losses
sec=fronth=8b3204cccd40
c7 verified · fact Clean/dirty reference comparison
The soiling ratio is often approximated from the short-circuit current of a soiled device compared with a clean reference device.
- soiling losses
sec=fronth=8b3204cccd40 - Soiling Losses – Impact on the Performance of Photovoltaic Power Plants
sec=3.1h=1bd67b0ecb1e
verified by: joshuahamsaverified on: 2026-10-16
c8 verified · fact Optical soiling sensor
Commercial sensors use LED optics or image-processing cameras.
- Soiling Losses – Impact on the Performance of Photovoltaic Power Plants
tbl=5.r2h=2e85ddcb867f
verified by: joshuahamsaverified on: 2026-10-16
c9 drafted · lead Performance ratio trend analysis
- soiling losses
sec=fronth=8b3204cccd40
c10 verified · fact Energy ratio analysis
Pattern matching on the energy ratio usually needs 5 or more days of data. Spans shorter than 4 days are not detected.
- pv model losses
sec=fronth=10001d881d82
verified by: joshuahamsaverified on: 2026-10-16
c11 verified · fact Weather-normalized production comparison
- soiling losses
sec=fronth=8b3204cccd40
verified by: joshuahamsaverified on: 2026-10-16
c12 drafted · lead Visual inspection
- soiling losses
sec=fronth=8b3204cccd40
c13 drafted · lead IV curve tracing
Shows how clean, uniformly soiled and unevenly soiled modules differ.
- Soiling Losses – Impact on the Performance of Photovoltaic Power Plants
sec=3.1h=1bd67b0ecb1e - Guidelines for Operation and Maintenance of Photovoltaic Power Plants in Different Climates
fig=95h=64f5d28c60e3
review note: support check: partial - Passages show IV curves of clean, uniform and non-uniform soiling, but IV curve tracing isn't stated as a detection method for soiling.
mitigated_by
c14 verified · fact Anti-soiling coating
Described as one of the most widely used mitigation methods.
- soiling losses
sec=h7h=22baf3f6fdbf - soiling losses
sec=fronth=8b3204cccd40
verified by: joshuahamsaverified on: 2026-10-16
c15 drafted · lead Cleaning schedule optimization
Base the schedule on the measured soiling rate and the cost of cleaning.
- soiling losses
sec=fronth=8b3204cccd40
c16 drafted · lead Module tilt optimization
- soiling losses
sec=fronth=8b3204cccd40
Referenced by
- Bifaciality
related_toc2 - Energy loss waterfall
related_toc4 - Energy yield assessment
related_toc7 - Flawed PAN File Yield Losses
distinguished_fromc11 - Glass Corrosion or Abrasion
leads_toc12 - Snow Accumulation Yield Losses
distinguished_fromc19 - Spectral Effect Yield Losses
distinguished_fromc11