The most relevant milestones are marked below. They are in chronological order, and some of them could not appear in a specific project (for instance, not all projects have a limited notice to proceed or the payment milestones can vary a lot from project to project).
Limited notice to proceed (LNTP): in this milestone an agreement is reached between the party to perform some works (for instance, to purchase some long lead time item, such as the substation main transformer). It makes sense when it’s necessary to accelerate the project for some reason.
Advance payment: this is a down payment paid by the customer before the start of the works. It is usually done to secure the production slot of the turbines
Commencement date: in this milestones, all condition precedents are met and the contract is activated.
Payment milestones: every contract has different payment milestones (and different percentage of payment associated with each milestone). However, some “standard” milestones are marked below to give you an idea of how they could look like:
- WTG ex works
- WTG shipped
- WTG erected
- WTG commissioned
Mechanical completion: in this milestone, a certificate is issue stating that the wind turbine has been erected following the relevant technical specifications and it’s ready to start Commissioning
Commission certificate: at the end of commissioning (a set of test done to confirm that the turbine is ready for production) the turbine is ready to start trial operations. A certificate is issued to formalize this fact.
Taking over certificate (TOC): this milestone is usually linked to transfer of risk and beginning defects liability period for a specific turbine (the “defects notification period”).
Provisional acceptance: from this point in time, usually an Operation and Maintenance contract for the wind farm start.
Final acceptance: in this milestone the customer formally accept that the wind farm is complete, fully operational and compliant with the relevant technical specifications.