Transfer of title and transfer of risk are 2 key concepts in wind farms contracts (and, presumably, in many other comparable businesses). They appear in both EPC and Supply Only agreements.
This is what they usually means:
Transfer of title (ToT): the ownership (of the entire turbine or of one of the component of the wind farm, such as the foundation) is transferred to the buyer.
Transfer of risk (ToR): risk of damages and losses is transferred to the buyer.
Although it may look counterintuitive they do not have to happen at the same point in time: for instance, an EPC contract could have transfer of title when a certain percentage of the wind turbine is paid -for instance, 80%- and transfer of risk only after commissioning (that is, the turbine is installed, tested and ready for production).
When the relevant percentage is paid is defined in the projects cash flow. In general, it could happen that the transfer of title happen many months before wind turbine installation.
The percentage of the wind turbine price to be paid to have transfer of title is usually one of the key negotiation topics. For the sake of clarity, the wind turbine seller would retain some case of security (e.g. a bank bond) until the equipment is paid in full in case the buyer stop the payments after the transfer of title.
It is worth to notice that one party (or both) might be interested in an early ToT or ToR, for instance if they are linked to revenue recognition. For instance, in some Supply Only or Supply and Install contracts revenue recognition is at ToR, so the turbine seller want to have it as soon as possible.
For a variety of reasons, it could be the buyer interested in an early ToT or ToR, possibly even before the completion of the wind farm balance of plant (basically, when the wind farm is not ready for installation). In a similar scenario the turbines would be delivered to a temporary storage area where the ToT and ToR would happen.
One more interesting point is that, in some jurisdictions, a sales tax could become applicable when the ownership of the turbines is transferred. This could be a good reason for an early or late transfer of title in a different jurisdiction.