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Water pressure and water volume for cleaning large PV systems

  • Expert Knowledge

Problem: Poor cleaning due to incorrect water usage

Operators of large photovoltaic systems face a recurring technical problem:

  • Many cleaning methods use too little water or utilize high-pressure cleaners – which may seem powerful for solar modules, but can damage the sensitive glass surface.
  • Pure low pressure on smooth PV surfaces can cause abrasion from dirt particles without a sufficient water volume, instead of dissolving them.
  • Furthermore, height differences and long hose distances lead to water pressure losses that reduce the cleaning effect.
  • Incorrectly sized hoses further reduce water throughput and thus the cleaning performance.

→ Studies on PV cleaning techniques recommend adjusted water volumes and suitable pressure to optimize cleaning efficiency and module protection.

Solution: Low pressure + sufficient water volume + correct hose technology

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1. Pre-cleaning and main cleaning with water

For optimal results, pre-cleaning and main cleaning with water is recommended, ideally with osmosis water:

Osmosis water is free of salts, minerals, and residues, offering a gentle yet effective cleaning without additives.

The filtered water creates a flushing effect that gently dissolves dirt without rubbing.

Benefit: Gentle removal of dirt, lower risk of scratching, and less post-cleaning required.

2. Low-pressure range instead of high pressure

Solar cleaning robots work effectively in the low-pressure range (approx. 2–4 bar) – this is roughly the same as a standard tap connection. Low-pressure cleaning ensures the surface of the modules is not damaged. Benefit: Gentle cleaning without risk to module glass or seals.

3. Consider water pressure losses and hose diameter

Pressure losses are caused by: Height differences: Rule of thumb: ~1 bar pressure loss per 10 m height Long hose lengths and small internal diameters: reduce water throughput hyCLEANER recommends supply hoses with an internal diameter of at least 10 mm for the solarROBOT series to ensure sufficient water flow. Benefit: Constant water pressure and higher cleaning effect across the entire system.

Advantages of the correct water strategy

Challenge Solution Result
Dirt rubs instead of dissolving Osmosis water + sufficient water volume Less abrasion & cleanliness
Pressure losses Correct hose + pressure planning Uniform cleaning
Module risks Low pressure instead of high pressure No surface damage
Dirt rubs instead of dissolving
Solution
Osmosis water + sufficient water volume
Result
Less abrasion & cleanliness
Pressure losses
Solution
Correct hose + pressure planning
Result
Uniform cleaning
Module risks
Solution
Low pressure instead of high pressure
Result
No surface damage
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