Renewable energy
The Essential Guide to Maintaining and Cleaning Your Solar Panels in 2026
A poorly maintained solar panel can lose up to 25% of its efficiency. Discover our practical tips for cleaning, maintaining and maximizing your solar panel production in Belgium.
· 15 min read · VCN Energy
Why maintaining and cleaning your solar panels is essential
Solar panels are an ecological and economical must-have. But to keep them producing energy at full capacity, regular maintenance is essential. A poorly maintained solar panel can lose up to 25% of its efficiency, directly translating into lower electricity production and a longer return on investment.
In Belgium, weather conditions — rain, pollution, spring pollen and autumn leaves — create deposits that gradually accumulate on the glass surface. While natural rain removes some dust, it's not enough to remove stubborn stains like bird droppings, lichen or pollution residues.
Key figures on efficiency loss
| Type of soiling | Estimated efficiency loss |
|---|---|
| Light dust | 2 to 5% |
| Urban/industrial pollution | 5 to 15% |
| Dried bird droppings | 10 to 20% |
| Lichen/moss | 15 to 25% |
| Mixed accumulation, uncleaned | 20 to 30% |
The main enemies of your solar panels
1. Dust and fine particles
Airborne particles always end up settling on panels. In rural areas, pollen and agricultural residues are the main culprits. In urban environments, diesel particles and industrial soot create a greasy film that's harder to remove.
2. Leaves and plant debris
If your panels are installed near trees, dead leaves, pine needles and small branches can accumulate, especially in corners and gaps.
3. Bird droppings
Often underestimated, bird droppings are one of the most harmful factors. A single dried dropping can create a "hot spot" on the panel, reducing production of the entire chain of series-connected cells.
4. Air pollution
Near motorways or industrial areas, polluting particles accumulate quickly and form a greasy film difficult to remove with water alone.
5. Limescale and mineral deposits
In Belgium, tap water is often hard. Cleaning with unfiltered tap water can leave white marks that also reduce light transmission.
How often should you clean your solar panels?
It's recommended to visually inspect your panels every 3 to 6 months and carry out a thorough cleaning 1 to 2 times per year. Ideal periods:
- Spring (March-April): after winter
- Autumn (October-November): after leaf fall
How to clean your solar panels effectively
Required tools
- A garden hose with low pressure or a bucket of water
- Demineralised water or rainwater
- A soft sponge or microfibre cloth
- A telescopic brush with soft bristles
- A mild biodegradable soap
- A soft rubber squeegee (optional)
⚠️ What you should NEVER use
- Pressure washer: risk of cracking tempered glass
- Aggressive chemicals: ammonia, bleach, acetone
- Abrasive sponges or scrapers: scratch the anti-reflective coating
- Hot water on cold panels: thermal shock risk
6 steps for perfect cleaning
- Choose the right time: clean early morning or late afternoon
- Turn off the inverter: safety first
- Rinse with clean water: from top to bottom
- Clean stubborn stains: with diluted mild soap
- Rinse thoroughly: with demineralised water
- Let dry: air dry or use a soft squeegee
Should you call a professional?
When to DIY
- Panels are easily accessible from ground level
- Light soiling (dust, pollen)
- You're comfortable working at height
When to call a professional
- Difficult-to-access roof
- Lichen or embedded deposits
- Significant production drop
- Physical damage to panels
Professional cleaning by VCN Energy
A professional cleaning includes: complete visual inspection, demineralised water cleaning, anti-moss treatment, fixing checks, and a performance report.
Indicative price: from €200 for a standard residential installation (10-20 panels).
Financial impact: how much does a dirty panel cost you?
For a 6 kWp installation in Walloon Brabant:
- Annual optimal production: ~5,400 kWh
- Average kWh price 2026: ~€0.35
- With 15% loss due to soiling: ~€283/year lost
A professional cleaning at €200 pays for itself in the first year.
FAQ
Doesn't rain clean the panels enough?
Rain removes light dust but not dried droppings, lichen or greasy pollution. Manual cleaning remains necessary 1 to 2 times per year.
Can you walk on solar panels?
Absolutely not. Photovoltaic cells can develop micro-cracks under a person's weight.
Is vinegar suitable for cleaning panels?
Diluted vinegar can occasionally be used for limescale marks, but the acidity can damage seals and anti-reflective coating over time. Prefer demineralised water with mild soap.
Conclusion
Regular maintenance and cleaning of your solar panels is a minimal investment that guarantees optimal production for 25 to 30 years.
Need professional solar panel cleaning in Walloon Brabant, Brussels or Wallonia? VCN Energy offers a complete cleaning and inspection service. Contact us at 010 80 20 92 or book online.