licenses are usually fixed amounts, but there can be taxes/levies which are proportional to production. As Enercon notes, the main difference is linked to wind levels (or, in case of poor performance, to operational failure).

O&M (operations and maintenance) agreements can be structured as flat fees (effectively linked to nominal capacity) or proportional fees (linked to actual production) or a combination of both. Payments can also be linked to "availability" (ie the percentage of time the wind turbines are actually able to produce power, irrespective of what the wind is). The main differences are linked to whether the operator (which is typically the turbine manufacturer) takes wind risk, and to what extent it takes performance risk on its own turbines.

Nothing that hasn't been done for decades in this and other industries.

Wind power