How to Clean Solar Panels: Best Practices for Higher Efficiency

You’ve invested in solar panels to generate your own electricity? An excellent decision! But did you know that simple, regular maintenance can make a real difference to your energy production? Discover how to clean your photovoltaic panels easily and enjoy optimal performance all year round.

Why Is It Important to Clean Your Solar Panels Regularly?

Your panels work for you every day, exposed to natural elements such as rain, wind, dust, pollen, and pollution. Over time, these particles build up on the surface, forming a thin layer of dirt that blocks sunlight. The result? Your system produces less energy than it should.

The Tangible Impact on Your Energy Production

The numbers speak for themselves: without regular cleaning, the efficiency of your photovoltaic panels can drop by 5% to 25%, depending on your environment and the type of soiling involved. By contrast, a well‑maintained solar installation can retain up to 95% of its production capacity even after 20 years of operation.

In practical terms, if your system normally produces 4,000 kWh per year, dirty panels could cause an annual loss of 200 to 1,000 kWh. This loss directly affects your electricity bills and the overall profitability of your photovoltaic system. Discover how SunPower panels maximise energy production thanks to their high‑efficiency solar cell technology.

Extending the Lifespan of Your Installation

Beyond immediate performance, regular maintenance protects your investment over the long term. Over time, accumulated dust and debris can cause dangerous localised increases in temperature on the panel surface. Preventive cleaning helps you avoid costly repairs and keeps your system in excellent condition throughout its entire lifespan. At SunPower, our panels benefit from a 40‑year warranty, the most comprehensive on the market.

What Causes Solar Panels to Get Dirty?

Solar panels are designed to be highly durable, but their surface is still exposed to various forms of soiling that reduce efficiency.

The Invisible Enemies of Your Solar Production

• Dust and pollen: particularly abundant in spring, they form a film that reduces sunlight absorption
• Fallen leaves: in autumn, they accumulate and create shaded areas that negatively impact performance and can be harmful to panel health
• Bird droppings: stubborn and opaque, they locally block photovoltaic cells
• Urban pollution: in cities, fine particles leave a greyish layer on equipment
• Salt and sand: in coastal areas, sea air covers the surface with saline deposits

Even if your panels are equipped with a self‑cleaning coating, these elements inevitably accumulate over time, gradually reducing the efficiency of your system and your overall energy production.

When Should You Clean Your Solar Panels?

Timing is essential to optimise performance while avoiding unnecessary effort.

How Often Should You Clean Your System?

For most photovoltaic systems, cleaning twice a year is enough to maintain optimal production. However, certain environments require closer attention:

• Near farmland or agricultural zones: dust and pollen increase dirt build‑up (3–4 cleanings per year recommended)
• Dense urban areas: pollution may require more frequent cleaning
• Coastal locations: salt and sand demand regular maintenance
• Flat roofs: a tilt of less than 15° allows dirt to accumulate, as rain runoff is insufficient

For large commercial & industrial (C&I) flat roofs, this issue is even more pronounced due to larger surface areas and higher exposure to atmospheric pollutants. In these cases, professional quarterly cleaning is strongly recommended. C&I installations also require specialised equipment and enhanced safety protocols for working at height.

Pro tip: monitor your energy production. An unexplained drop in output or higher electricity bills often signal that cleaning is needed. Learn how to optimise your solar production with SunPower expert advice.

What Is the Best Time of Day to Clean Solar Panels?

Never clean your panels in direct sunlight.

Morning Is Your Best Ally

Clean your panels early in the morning, before sunrise if possible. At that time, the surface is still cool. During the day, panel temperatures can reach 80°C, while cleaning water is much cooler - this thermal shock can damage photovoltaic cells and leave marks.

Additionally, midday sun causes water to evaporate too quickly, leaving mineral residues that reduce cleaning effectiveness and impact energy production.

How to Clean Your Solar Panels Safely

Cleaning your panels is a simple task that requires minimal equipment to maintain peak performance.

Recommended Cleaning Equipment

Basic tools you’ll need:

• Lukewarm water (not cold, not hot - ideally room temperature)
• A soft cloth or non‑abrasive sponge
• A telescopic pole or soft brush (for roof‑mounted systems)
• Foam squeegee (optional, for stubborn stains)

Professional tip: use de‑mineralised water to avoid limescale stains. Tap water can leave a white residue that reduces cleaning efficiency.

The 4‑Step Cleaning Method

1. Wet the surface with lukewarm water
2. Gently wipe using circular motions with a soft cloth
3. Rinse thoroughly with clean water
4. Allow to air‑dry or use a foam squeegee

Rinse your cloth every square metre to prevent spreading dirt back onto clean panels.

What Should You Absolutely Avoid?

To protect your solar system and maintain performance, never:

• Use a high‑pressure washer (even low pressure can damage seals and cells)
• Use hard brushes or scrapers
• Walk on the panels
• Apply chemical cleaners or detergents
• Clean during extreme heat

For stubborn stains, be patient and gentle - lukewarm water and a foam squeegee only.

Should You Clean the Panels Yourself or Hire a Professional?

It depends on accessibility and safety.

DIY Cleaning: Cost‑Effective and Practical

If your panels are easy to reach and you’re comfortable with basic DIY tasks, cleaning them yourself is an economical option. You’ll only need water, a soft cloth, and possibly a telescopic pole (an investment of around €100, typically paid back over a few years through maintained energy output).

Professional Cleaning: Safety and Expertise

Professional intervention is strongly recommended if:

• Your installation is high or on a steep roof
• Panels are difficult to access
• There are visible cracks or damage
• You lack time or confidence

Expect €100–€250 per visit. Many installers offer annual maintenance contracts that include cleaning and system inspection.

Professional advantage: beyond surface cleaning, technicians inspect the inverter, wiring, and overall system condition - often detecting invisible issues that affect production. Find a SunPower‑certified installer near you.

Your Solar System Deserves the Best Care

Regularly cleaning your solar panels ensures optimal energy production and protects your investment for the long term. With just two cleanings per year and a few simple best practices, you can maximise the performance of your photovoltaic system.

At SunPower, we design high‑performance, durable panels built to last for decades. Discover why SunPower leads the solar industry with cutting‑edge technology and maximum production - even in low‑light conditions.

Ready to optimise your system?

Get a personalised quote and benefit from expert guidance for a powerful, future‑proof solar solution.