What determines the cost of cleaning a wind turbine (and why the price per machine does not tell the whole story)
Two quotes with the same price per machine can cost very different amounts. The cost of cleaning a wind turbine depends on six things, and the downtime, which appears on no invoice, is usually the largest.
This is not a price list: our rates come with each proposal, fixed per machine and scope. What is worth explaining is what the price depends on, because that is what lets you compare two quotes that look alike and are not.
1. The scope
Cleaning the tower does not cost the same as cleaning the whole machine. The usual scopes are full (blades, hub, tower and nacelle), blades and hub, tower only and nacelle only. The norm is to order the full clean, because once the crew is at the foot of the machine, each additional scope costs little more; cleaning only the tower and coming back six months later for the blades means paying two mobilisations.
2. The number of machines
Moving a crew to a site costs the same for one machine as for ten. That is why almost every contractor has a minimum order (ours is 4 turbines per campaign, with mobilisation included from there) and why the price per machine falls as the campaign gets longer. A site with four isolated machines is the most expensive case per unit, and also the one fewest contractors want.
3. Height and size
A large-rotor machine has more metres of blade and more tower to clean. Rates are usually tiered by rotor diameter, and each method has a physical limit: with a drone, we work on nacelles up to 100 metres.
4. Access and logistics
Tracks in poor condition, sites hours from the nearest water, mountain locations with short weather windows: all of that is crew days that somebody pays for. A serious contractor asks about it before quoting.
5. The method
This is where quotes stop being comparable. A rope access team takes 4-5 days per machine; a drone, one day. Even if the price per machine were identical, the real cost to the site is not, because of the next item.
6. Downtime, which appears on no invoice
While it is being cleaned, the machine does not generate. The contractor does not invoice that lost production, but the owner pays it, and it is proportional to the days of intervention. That is why drone cleaning reduces cost and lost production by 75-80% compared with rope access: it is not that the day rate is cheaper, it is that the machine is stopped for hours instead of days. The full arithmetic is in this article.
How to compare two quotes
- Ask for the price per machine and per scope, with mobilisation stated explicitly.
- Ask for the days of downtime per machine, and put them in the calculation.
- Ask what is included: permits, public liability insurance, water, photographic evidence. In our case all of that is inside.
- And ask what the method does not do. A quote with no limits is not a quote, it is a brochure.
With the number of turbines, the location and the rotor diameter, we return a fixed proposal within two working days. That is what any contractor needs to give you a real price.