How often should a wind turbine be cleaned (and why nobody gives you a number)

It is the first question in almost every conversation and the one with the worst answers online. Plenty of articles quote round numbers, every twelve months, every two years, without citing where they came from. We are not going to do that.

The honest answer

There is no public, single, universal manufacturer recommendation setting how often a wind turbine should be cleaned. Maintenance manuals cover the critical systems of the machine in detail, but exterior cleaning of blades, tower and nacelle does not carry the same status as a scheduled task with a fixed interval.

What does exist is industry practice. And practice converges on at least one visual review per year, with cleaning driven by whatever that review finds.

What actually drives the interval

Two sites with the same machine and the same commissioning year can need different cadences. These are the factors that explain it.

Salinity

Coastal sites build up salt deposits far faster and more aggressively. It is the single factor that shortens the interval most.

Dust and agricultural activity

A site surrounded by farmland, with seasonal harvesting and tillage, takes a particle load that a site on clean upland does not. Soiling also binds differently depending on site humidity.

Insects

Build up on the leading edge is seasonal and highly location dependent. At some sites it is the main reason for a cleaning campaign; at others it is irrelevant.

Fleet age

On machines that have gone years without an intervention, the first clean is not maintenance: it is recovery. After that, the cadence can be stretched.

How we approach it

Starting with a visual inspection before committing to a cleaning campaign is almost always cheaper than the other way round, and it gives you something a generic figure cannot: the real condition of your machines.

With a photographic report per turbine you can genuinely prioritise. Which ones need work this year, which ones can wait, and which scope the soiling is actually on, because it is not always where you would assume. There are sites where the tower is acceptable and the nacelle is not, and full scope campaigns that could have been single scope.

When cleaning and inspection are booked together, the inspection is built into the cleaning flight: each machine is handed over with its before and after. Booking inspection on its own makes sense when the goal is to document fleet condition to decide with data, or to build the internal case for a campaign.

What we are not going to tell you

We are not going to give you a percentage of production lost to soiling. Several figures circulate in the sector, they cite each other, and none arrives with a measurement we can verify at a specific Spanish site. Publishing one would be easy and would read well on this page. We do not have it.

What we can stand behind is the operational side: what gets cleaned, in how long, with what equipment, what evidence is handed over and what the before and after photographs show. With that, and with the real condition of your machines, the cadence decision makes itself.