About the Soiling Risk Assessment
Soiling risk assessment scores a solar site's susceptibility to panel soiling based on local dust levels, precipitation patterns, proximity to pollution sources, and bird activity — used to set cleaning frequency, evaluate robotic vs manual cleaning, and model site-specific soiling loss in energy yield estimates.
How to calculate it
- 1Score dust exposure: distance from unpaved roads, construction sites, industrial sources, and agricultural fields (harvest-season dust is severe in Punjab/Haryana).
- 2Score precipitation: sites with > 800 mm annual rainfall and frequent moderate showers self-clean more effectively. Sites in arid zones (Rajasthan, Gujarat) with < 400 mm rainfall are high-risk.
- 3Score bird activity: roosting birds cause localised heavy soiling that accelerates hotspot formation. Note proximity to water bodies, trees, and power lines.
- 4Combine scores into a soiling risk category: Low (coastal/humid), Medium (urban/plains), High (semi-arid), Critical (desert/industrial).
- 5Map risk category to expected soiling rate and recommended cleaning frequency.
Worked example
A 2 MW plant near Bikaner, Rajasthan: desert location (critical dust), < 300 mm rainfall, no bird issues. Risk: Critical. Expected soiling rate: 0.15–0.20%/day. Recommended cleaning: every 7–10 days in the dry season, every 14 days post-monsoon. Robotic cleaning justified at this scale.
What you can calculate
- 5 dust zones
- Annual loss %
- Cleaning ROI
- Revenue impact
Frequently asked questions
How do I know if my solar site has a high soiling risk?
High soiling risk indicators: (1) visible dust on the panel surface within 2–3 days of cleaning, (2) panels near agricultural fields during harvest season (post-October in North India), (3) near industrial facilities with stack emissions (flyash, cement dust), (4) close to unpaved roads with daily vehicle traffic. Compare cleaned vs uncleaned panel output with a monitoring system — a > 3% difference after 2 weeks confirms high soiling.
Does soiling affect all panels equally?
No — soiling is uneven. Panels at the leading edge of the array (facing the wind) accumulate more airborne dust; panels near bird-roosting spots accumulate heavy, localised deposits; lower-row panels in a steeply tilted array are cleaner (rain runs off more effectively). IR thermography and panel-level monitoring (with microinverters or power optimisers) reveal non-uniform soiling across the array.
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