When solar panel cleaning is worthwhile
Rain removes some deposits, but not every type of dirt. The actual condition, surroundings and safe access to the panels determine whether cleaning is useful and how it should be arranged.
Decide by condition, rather than a fixed calendar
On sufficiently tilted modules, rain can wash away loose deposits. Stubborn bird droppings, dirt along frames and site-specific residues may remain. Low-tilt installations and sites exposed to agricultural, traffic or industrial dust deserve particular attention.
Annual cleaning is therefore not necessary for every system. Have the visible condition and operating data assessed together. Lower electricity output may also result from weather, shading or a technical fault; it does not prove heavy soiling on its own.
Individual stubborn patches may matter even when the rest looks clean. For an initial enquiry, observations from a safe position or existing photographs are enough. Do not climb onto the roof to prepare the request.
Separate cleaning from technical maintenance
Solar installations may produce electricity or heat. Cleaning covers photovoltaic module surfaces or the outside of thermal collectors. Work on electrical equipment or the heat-transfer circuit is not automatically included.
| Service | What to clarify |
|---|---|
| Surface cleaning | Which modules or collectors, frames and accessible edges are included? |
| Visual inspection | Will apparent damage be recorded? This is not an electrical inspection. |
| Maintenance / repair | Measurements, inverter work or thermal circuit work require separate agreement. |
| Roof / gutters | Define additional surfaces and their cleaning separately. |
The method must suit your panels
Glass, coatings, seals and connections place requirements on cleaning. Ask whether the proposed method complies with the instructions for your actual modules. Existing manufacturer or system documents help, but are not a prerequisite for an initial request.
Contractors may use suitable soft brushes and treated water. Not every detergent, water pressure or robot is approved for every system. Temperature conditions matter as well. A universal recommendation to use washing-up liquid or a pressure washer would therefore be inappropriate.
Modules must not be used as a walkway. Damaged components or suspect connections should be assessed before cleaning. Recording visible problems during the job should not be presented as a complete technical inspection.
Access and safety affect the work required
Mounting position, height, roof shape and access determine how the work can be carried out. A ground-mounted system differs from a steep house roof or a façade. A roof hatch alone does not establish a safe workplace.
The contractor must assess falls from and through the roof and choose suitable equipment. Whether a platform, another access system or existing protective equipment can be used belongs in the work plan. Existing anchor points should not be assumed suitable without checking.
Also clarify water supply, equipment space, vehicle access and operational restrictions. Fragile or potentially contaminated roof materials require a compatible approach. You do not need to carry out your own material investigation to submit an enquiry.
A square-metre rate is not the complete price
The relevant area is the module or collector surface being cleaned, not automatically the entire roof. Panel counts and system documents can help estimate it. A fixed kWp-to-area conversion is not reliable across panels of different sizes and efficiencies.
One Swiss tariff checked in October 2026 lists CHF 3.50 per m² for manual cleaning, plus CHF 150 base costs and CHF 157.50 for setup and removal, excluding VAT. For an assumed 50 m², this totals CHF 482.50 before travel, vehicle costs, VAT and any additional work. This is a calculation from one tariff, not a final price for your installation.
Another regional contractor publishes CHF 5 per m² plus travel for easily accessible systems up to 50 m²; VAT and any minimum job charge are not fully quantified. These examples cannot therefore be combined into a dependable market price range.
- Same scope. Compare the same panel area, soiling and additional roof work.
- Complete cost. Include travel, setup, access equipment, water, supplements and VAT.
- Records. Agree whether photographs or reports of visible damage are included.
Assess the benefit without assuming a fixed output gain
No fixed percentage increase can be promised for every installation. For photovoltaics, the relevant figures are how much energy cleaning can actually recover and what that energy is worth when used on site or exported.
A purely hypothetical example: of 200 additional usable kWh, 100 kWh might replace purchased electricity at 30 centimes and 100 kWh might be exported at 15 centimes. That would be worth CHF 45. The energy and tariffs are chosen assumptions, not a forecast or current market prices. The same kWh cannot count as both avoided purchases and exported electricity.
Compare the expected benefit over a plausible period with the complete cleaning cost. Unusual output or damage may call for a technical assessment first. For solar thermal systems, assess the heat produced rather than applying an electricity-bill calculation.
Frequently asked questions
Does every solar system need annual cleaning?
No. Tilt, surroundings, deposits and actual condition determine the need. A fixed interval does not suit every system; inspections and cleaning should be planned separately.
Does cleaning guarantee more electricity?
It can reduce losses caused by soiling. A fixed percentage gain is not reliable without assessing the particular system. Weather and technical causes also matter.
Is maintenance included in the cleaning price?
Only if expressly agreed. A visual check does not replace an electrical inspection or maintenance of a solar thermal circuit.
Do I need to know the exact area?
No. An approximate panel count or an area figure you already have helps with the initial enquiry. Missing measurements can be clarified later; do not climb onto the roof to obtain them.
Can the gutters be cleaned at the same time?
Combining visits may help, but the gutter work needs its own scope and price. Access and suitable methods may differ from those for the panels.
