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WATER · CHEMICALS4 min read

What Should Solar Panels Be Cleaned With?

Short answer: Clean solar panels with pure (demineralized) or reverse-osmosis water kept below 30 ppm TDS, combined with soft nylon brushes — used this way it is sufficient on its own and needs no chemical additives. Avoid tap water, which leaves lime marks, and never use detergent, glass cleaner, vinegar, bleach or solvents. Doka's FK-1000 V3 and FK-600 V2 robots can feed osmosis water directly.

Summary
  • Pure or osmosis water (TDS below 30 ppm) plus soft nylon brushes is the correct method and needs no chemicals.
  • Pure (demineralized) water leaves no residue and is the first choice for professional cleaning; rainwater only works filtered and for pre-cleaning.
  • Never use tap water (lime marks), detergent, glass cleaner, vinegar/acids, bleach, acetone or solvents — they damage the anti-reflective coating.
  • Doka FK-1000 V3 and FK-600 V2 robots run 6-30 L/min adjustable flow, accept osmosis water directly, and offer a waterless dry mode for desert sites.

Pure water, osmosis water or detergent? The right cleaning agent is critical for panel longevity. The wrong material permanently damages the anti-reflective coating.

Short answer

Pure water or osmosis water (TDS < 30 ppm) is the right choice for panel cleaning. Combined with soft nylon brushes, it is sufficient on its own. You don't need any chemical additives.

Water types — detailed comparison

✅ Pure water (Demineralized)

Water with all minerals removed. Leaves no residue when it dries. The first choice for professional cleaning. Produced via filter systems; small and large infrastructure options exist.

✅ Osmosis water (Reverse Osmosis)

Highly purified water. Performance is similar to pure water. TDS should be below 30 ppm. Possible to produce on-site by installing an RO unit on your site's water source.

⚠️ Rainwater

Naturally pure but can pick up dust and sediment from the atmosphere. Usable if filtered. Not sufficient on its own; useful for pre-cleaning.

❌ Tap water (municipal supply)

In most regions, water hardness is high. Lime deposits leave white marks on the panel surface. Those marks block light — sometimes worse than the original soiling. Don't use.

❌ Well water

Mineral content varies wildly by region. Risky without a TDS measurement first.

Chemicals — absolutely not

None of the following should be used to clean solar panels:

  • Detergent / dish soap: Degrades the anti-reflective coating over time.
  • Glass cleaner: Most contain ammonia, harmful to the coating.
  • Vinegar / acids: Cause permanent surface damage.
  • Bleach: Chlorinated compounds damage the frame and cell contacts.
  • Acetone or solvents: Never, under any condition.

Exception: special cleaners explicitly recommended by the panel manufacturer for very stubborn oil or paint marks. Even then, pure water + mechanical brushing is usually sufficient.

Doka FK robots' water management

FK-1000 V3 solar panel cleaning robot and FK-600 V2 models run with 6 — 30 L/minute adjustable water flow. Water tank integration is available; osmosis water can be fed directly into the robot. The operator adjusts flow rate from the remote based on site soiling level.

In dry mode, the robot uses no water at all — just the soft imported Nylon 6.6 brush to remove loose dust. This mode is critical for desert and remote sites.

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