Cleaning solar systemsOnly when needed.

A solar system needs little care. On pitched roofs, the rain usually washes the modules clean. Even so, there are cases where cleaning is worthwhile. We check on site whether that applies to you, before you spend any money.

When does cleaning make sense?

Dirt collects mainly where the rain does not wash it off or where a lot accumulates:

• Low tilt: Below about 10 degrees, dust and dirt stay on the lower edge.
• Farms: Barn air, dust and pollen form a film on the glass.
• Trees nearby: Leaves, resin and pollen.
• Birds: Droppings form marks that shade cells and can lead to hotspots.
• Dusty location: Road, building site, commercial premises or sand.

If the dirt is light, the loss of yield is usually small. With heavy dirt, it can become noticeable, especially on flat and shaded systems. Whether cleaning pays off depends on the system. We tell you if it is not worth it.

How do you clean solar modules properly?

The modules are glass surfaces, but not car windscreens. Wrong cleaning damages the coating and can put the warranty at risk. This is how we work:

• Demineralised water: It dries without limescale marks.
• Soft brush: No scratches on the glass.
• No high-pressure washer: The pressure can attack seals and cells.
• No chemicals: Aggressive cleaners attack the coating and frame.
• Cool time of day: Hot modules react sensitively to cold water.
• Secured: We work with fall protection and do not slide across wet modules.

Please do not clean the system yourself on the roof. The risk is high, the benefit usually small.

What does cleaning achieve?

A clean module lets more light through. How big the gain is depends on the system. With a light film of dirt it is small, with a crust of dust, bird droppings and pollen it is clearly larger. So we measure first and clean only if it pays off for you.

Maintenance and inspection at the same time

Cleaning is the best occasion for an inspection. When we are on the roof anyway, we check:

• Modules for cracks, discolouration and hotspots
• Connectors and cabling
• Fixings and mounting structure
• Inverter and error messages
• Yield figures compared with the forecast

If we find damage, for example after hail, we help further: see hail damage to your solar system.

Getting more from your existing system

The inspection on site often shows more than just dirt. Perhaps you use little of your own electricity and feed a lot into the grid. Then a battery to retrofit may be worthwhile. Or your roof has room for more modules: you can read more under extend your solar system. We discuss both if you are interested, with no obligation.

Request an inspection on site

Our locations are in Zumikon ZH and Lachen SZ. We travel across German-speaking Switzerland. In the appointment card, choose a date and enter your postcode. We check your system and tell you honestly whether cleaning is needed.