Does Dry Cleaning Scratch Solar Panels? What the Research Says
“Won’t a dry brush scratch my solar panels?” It is one of the most common questions we hear from plant owners considering waterless cleaning. It is a fair question: solar module glass carries a thin anti-reflective coating that helps more light reach the cells, and damaging it would cost generation for the life of the plant. Here is what research says, and how to clean dry without causing harm.
What the anti-reflective coating does
Most modern solar modules have an anti-reflective coating (ARC) on the front glass. It reduces the amount of sunlight that bounces off the glass, so more light reaches the cells. Like any coating, it can wear over time, through weather, sand abrasion and cleaning.
What the research says
A field study published in the IEEE Journal of Photovoltaics in 2024 by researchers at the Qatar Environment and Energy Research Institute (Figgis et al., “Abrasion of PV antireflective coatings by robot cleaning”) tested nine module types and five coating samples under 18 months of dry-brush robot cleaning in the Qatari desert, comparing daily cleaning, weekly cleaning and no cleaning at all.
The key findings were:
- Abrasion resistance varied widely between module types. Five of the nine module types lost more performance with more frequent cleaning; the other four did not.
- Scratch depth and number differed greatly between coatings.
- The authors concluded that both the robot’s “harshness” and the coating’s durability matter, and recommended field-testing specific robot and module combinations rather than relying only on lab tests.
In other words, dry cleaning is not automatically harmful or automatically safe. It depends on how the cleaning is done and which modules are being cleaned.
What actually causes scratches
- Hard or contaminated bristles that drag sand particles across the glass.
- Too much pressure from tools or people pushing down.
- People walking on modules, carrying grit on their shoes.
- Abrasive powders, scouring pads and harsh chemicals.
- Badly aligned machines that rub frames or glass edges.
Water-based cleaning is not risk-free either. Hard water leaves mineral deposits, detergents can leave residue, and wiping with a dirty cloth drags grit across the surface just like a dirty brush.
How to clean dry safely
- Use soft, purpose-made brushes designed for solar glass, not household brooms or scrubbers.
- Clean often and lightly. Frequent cleaning removes dust before it builds up into a layer that needs scrubbing.
- Keep brushes clean and replace them when worn or clogged.
- Never stand on panels.
- Check your module manufacturer’s cleaning guidelines and follow them.
- Watch your generation data. A well-run cleaning programme should show steady, recovered output after each cycle.
How MROBOTICS designs for panel safety
MROBOTICS products are built around gentle, waterless cleaning. The Aqualess Cleaner uses a dual-bristle brush head that combines soft and firm fibres to remove dirt while preserving the panel surface. The Solar Glide robot cleans without water and includes path-correction and safety-stop features so it stays aligned on the row. And because both products remove the need for anyone to walk on the panels, they eliminate one of the most common causes of cracks and scratches.
If you are planning robotic cleaning on a large plant, we recommend discussing your module make and coating with us so we can advise on brush setup and cleaning frequency for your site.
Frequently asked questions
Is waterless cleaning as effective as washing?
For the everyday dust that causes most soiling loss, frequent dry brushing is very effective. Stubborn deposits such as dried bird droppings may occasionally need spot cleaning with a damp cloth.
How often can I dry-clean without damaging panels?
With soft, clean brushes and light pressure, frequent cleaning is normal practice, and many robotic systems clean daily. Follow your module manufacturer’s guidance, and monitor output over time.
Will cleaning void my module warranty?
Cleaning in line with the manufacturer’s instructions is normal maintenance. Check the warranty document for any prohibited methods or materials.
Have questions about cleaning your specific modules? Talk to MROBOTICS.
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