Solar panel cleaning materials: your complete guide
A well-maintained solar panel system starts with the right solar panel cleaning material. With the appropriate tools, you will remove dirt safely, quickly and without streaks, keeping your yield up year after year.
By Hendrik Vandervoort4 min read
A well-maintained solar panel installation starts with the right solar panel cleaning material. With the appropriate tools, you remove dirt safely, quickly and without streaks, keeping your yield up year after year.
Why is the right material so important?
Not all brushes or cleaners are suitable for the fragile glass and anti-reflective coating of solar panels. If you use the wrong tools, micro-scratches, hot spots or even cell damage will occur - and you will see that reflected in your energy bill.
"We see in practice that panels treated with an abrasive sponge or standard window cleaner lose up to 8 % permanent efficiency," warns Hendrik, CEO of Solarco.
Efficiency loss due to dirt
A recent KU Leuven study shows that dust, bird droppings and pollen cause yield drops of up to 5 % within three months. In regions with agricultural or industrial emissions, this even goes up to 12 %. Regular cleaning with correct equipment is therefore pure profit.
Overview of indispensable solar panel cleaning equipment
| Material | Function | Practical tip |
|---|---|---|
| Telescopic handle (5-10 m) | Reaches roofs without ladder climbing | Opt for lightweight carbon to reduce arm fatigue. |
| Soft brush with split hairs | Dissolves dirt without scratching | Replace after ± 100 hours of use to avoid wear points. |
| Pure water | Rinses spotlessly, prevents limescale marks | Check the TDS value (< 30 ppm) for optimal results. |
| Rubber trigger (squeegee) | Dries the glass streak-free | Use only on glass; do not scrape over sealing rubbers. |
| pH-neutral cleaning agent | Soaks off oil and bird droppings | Avoid products containing ammonia or abrasive grit. |
| Microfibre cloths | Polishing edges and frames | Wash without fabric softener - that leaves film. |
| Fall protection & non-slip shoes | Working safely on pitched roofs | CE-certified harness and roof hook mandatory >2 m height. |
| Work gloves & safety goggles | Protect against sharp edges and splashing dirt | Choose nitrile gloves for good grip. |
Additional options for large installations
- Cleaning robot - Autonomous platform that handles up to 600 m² per hour without pressure on the glass.
- Portable drone spray - For hard-to-reach facade installations; observe local regulations.
Step-by-step guide
1. Preparation
- Switch off the inverter and let the panels cool down.
- Fill the pure water tank and test the TDS value.
- Install fall protection; anchor the line on a supporting ridge.
"Safety always comes first," stresses owner Sander. "A good anchor line and non-slip shoes are not a luxury but a necessity."
2. Pre-cleaning
- Rinse the panels liberally with pure water.
- Let the water soak for two minutes so that moss and mud soften.
3. Active cleaning
- Move the soft brush in long, overlapping strokes from ridge to gutter.
- Keep the brush constantly wet; drying while scrubbing will scratch it.
- Use pH-neutral soap only on stubborn spots and rinse immediately.
4. Replaying and drying
- Rinse away the foam completely.
- Pull the squeegee down in one smooth motion; overlap 2 cm at the next job to avoid streaks.
- Polish the frame edges with a microfibre cloth; inspect immediately for hairline cracks or loose cables.
5. Evaluation
Note down the date, TDS value of the water and details (resin, bird droppings, algae). This way, you build up a maintenance history that will come in handy later in warranty claims.
Common mistakes - and how to avoid them
- High-pressure cleaner - Water penetrates junction box; may cause short circuit.
- Household cleaner - Often too alkaline, affects the coating.
- Rain as an excuse - Rainwater contains minerals; leaves stains.
- Cleaning in full sun - Water evaporates at lightning speed → scale & streaks.
- Brushing with dry fibres - Friction creates electrostatic charge and actually attracts dust.
Maintenance myths debunked
Although solar panel cleaning seems simple, there are persistent misconceptions circulating that lead DIYers astray.
Myth 1: "A solid summer shower does the same as a professional cleaning."
Rain lowers the surface temperature and washes away some dust, but leaves behind minerals, insect debris and pollen that actually stick to the glass.
Myth 2: "A dash of washing-up liquid won't hurt."
Many household soaps contain fat solvents and salts that slowly degrade the dirt-repellent nanocoating, leading to faster dirt adhesion and micro-scratches in the future.
Myth 3: "Dark panels automatically get hot enough to burn away dirt."
Heat can dry out organic material, but actually fixes residue more strongly. Only a controlled rinse with pure water removes all residue without damaging the microstructure of the glass.
When do you call in a professional?
- Roof pitch > 35° or ridge difficult to reach.
- Installation larger than 30 panels (time vs yield).
- Persistent soiling such as moss, bird droppings or industrial precipitation.
- Missing safe anchor points.
Read more about our professional solar panel cleaning service Or schedule an inspection immediately.
Costing
Self-cleaning costs around €10-€50 per turn (in materials and time). Professional cleaning by Solarco starts at €125 for 25 panels and includes:
- Cleaning robot or telescopic brushes with pure water.
- Full safety assurance and insurance.
- Visual inspection + maintenance report.
- Average 10-20 % yield improvement.
Case study: 15 % more yield in Ghent
A customer in Ghent had its 42 panels cleaned by Solarco last April. Before cleaning, the daily yield was 11.2 kWh; the following month 12.9 kWh - an increase of 15 %. Thanks to the correct solar panel cleaning equipment and pure water, the additional yield is expected to outstrip cleaning costs within four months.
"Every kWh counts now that energy prices fluctuate so much," says Hendrik. "With one annual cleaning, you earn back tenfold over the life of the system."
Checklist for your next cleaning
| Step | Check | Done? |
| Fall protection mounted | ⬜ | |
| Pure water TDS < 30 ppm | ⬜ | |
| Bristles intact | ⬜ |
Ready to get the most out of your solar panels?
Click on Request a quote and receive a personalised quote within one working day. Feel free to share this article with neighbours or friends who also want to keep their panels in top condition - that way you'll help everyone get more green energy and lower bills.
Frequently asked questions
What equipment do you need to clean solar panels safely?
Safe cleaning calls for suitable non-abrasive brushes (with soft, flagged bristles that won't scratch) and pure water, without harsh cleaning agents or high pressure. A rubber squeegee used in one smooth downward stroke prevents streaks. For high or large roofs, professionals use telescopic poles or a cleaning robot, so nobody has to stand on the panels.
Can you use a pressure washer or Kärcher on solar panels?
No, never use a pressure washer. The high pressure can cause micro-cracks, damage the seals around the panel and force water into the junction boxes, leading to faults and lost yield. Always clean at low pressure, with pure water and a soft, non-abrasive brush.
Can you clean solar panels with washing-up liquid?
No, washing-up liquid or soap is not recommended, because it leaves a thin film that attracts dirt and causes streaks every time it rains. That soap film absorbs light and so reduces output, while alkaline products can damage the coating over time. Clean with pure water and suitable brushes instead, without soap.
How does Solarco clean solar panels?
Solarco cleans with professional equipment: suitable non-abrasive brushes and purified water, without harsh cleaning agents or high pressure. For large installations and solar parks, we use battery-powered, manufacturer-certified cleaning robots. A visual check and, if required, a thermographic check are carried out before and after cleaning.
What mistakes should you avoid when cleaning solar panels yourself?
Avoid pressure washers, hard or abrasive brushes, steel wool and household cleaning products, as they damage the coating and seals. Never clean the panels dry (this creates static and scratches) and never in full sun, because the water evaporates too quickly and leaves streaks. Don't use cold water on hot panels, to prevent thermal shock and micro-cracks.
Does rain clean solar panels?
No. Rain only washes away loose dust and often leaves minerals and stubborn dirt behind. Moss, lichen, bird droppings, pollen, Saharan sand and industrial fallout stay stuck to the panels, and it's precisely these layers that cost the most yield. Even a thin layer of dirt can mean 5 to 10% less output.
