Free tool
What is soiling costing your solar plant?
Put in your plant, how fast it soils and what a clean costs. See the revenue lost to dirty glass, the cleaning interval that costs least overall, and what changing your schedule could save.
Behind the numbers
Built by engineers, on measured data
RenewChem’s engineers built this calculator on published soiling research, from IEA PVPS, NREL and field studies, and on measurements from Southern African plants. It gives a planning estimate. Your plant’s real soiling rate, and what a better clean is worth, come from measuring it on site.
The real figure for your plant
- We measure soiling on your own strings, against a clean reference
- We identify what’s on the glass: dust that washes off, or a deposit that doesn’t
- You get a cleaning plan for your seasons, costs and water
About the calculator
Common questions
Still have a question?
Ask one of our engineers. Tell us about your plant and we’ll answer it properly.
Send your questionWhat does the calculator take into account?
Your plant’s size, yield and energy value, how fast its panels soil, how often you clean and what one clean costs. From these it estimates what soiling costs you each year, the cleaning interval that keeps soiling and cleaning costs lowest together, and what changing your schedule could save. It’s a planning estimate: a soiling measurement on your plant replaces the assumptions with facts.
Does rain change the answer?
Yes. Rain can wash loose dust off, but it doesn’t remove cement, scale or other deposits bonded to the glass, and in a long dry season it doesn’t fall at all. The regional rates are dry-season values, so the estimate fits the months when soiling costs most. Measuring your site shows how much your rain actually helps.
What soiling rate should I enter?
Use a measured rate if you have one. Published rates run from about 0.05% a day in typical conditions to 0.36% on heavy farmland and up to 0.5% near bird colonies (NREL 2018), and CSIR data from an uncleaned Pretoria tracker plant in dry winter showed performance-ratio losses of about 1.2–1.8% a week (roughly 0.2% a day). Our soiling-measurement service gives you your plant’s own number.
Where do the regional rates on the map come from?
From published soiling studies, and there are few. Measured PV soiling rates exist for only two places in the region: Kalkbult near De Aar in the Northern Cape (du Plessis, Stellenbosch University, 2017) and the CSIR campus in Pretoria (IEA PVPS 2022). Every other region borrows the nearest measured climate, such as NREL’s typical rate, Mediterranean sites in Spain and California for the Western Cape, or Pretoria’s dry winter for Zimbabwe and Mozambique, and the map says which. Treat them as a starting point: plants near mines, factories, farmland or the coast can soil far faster, and measuring your own site gives the real number.
Is this a quote or a guarantee?
No. It is a planning estimate from the figures you enter. For a real answer, we measure your soiling and water, and prove the result on your own strings in a free pilot.