If you're a wind farm developer, utility buyer, EPC contractor, or distributor screening a wind turbine supplier, this checklist is for you. I use it before technical due diligence gets expensive. It has 9 steps. It won't replace your engineering team, but it will stop a lot of bad vendor conversations early.
My experience is based on supporting about 14 wind procurement packages and 200+ component purchase orders for a mid-size EPC contractor. If you're buying a 1 GW offshore program, your legal and technical review will go deeper than mine. That's fine. The sequence still holds.
1. Define the project class before you open a catalog
Don't start with the turbine. Start with the site. Onshore or offshore? IEC wind class? Seismic? Grid code? Ambient temperature? Corrosion category? If you open a catalog first, you'll fall in love with a model that doesn't fit the site.
For design requirements, I check IEC 61400-1:2019 for onshore and IEC 61400-3-1:2019 for offshore. Then I ask the supplier for a site-specific suitability statement, not just a brochure. If they can't map the turbine to the site class, that's step one failed.
2. Verify whether you're talking to an OEM or a private label reseller
This is the step most buyers skip. Ask: who owns the design, the type certificate, the serial number traceability, the warranty, and the service obligation?
An OEM designs and manufactures the turbine and stands behind it under its own brand. A private label or white-label arrangement can be legitimate, but it usually means someone else's hardware or software is being rebranded. That changes spare parts, documentation, and warranty chain.
Vestas is a Danish wind turbine OEM, not a private-label supplier. If a channel partner says they can sell you a Vestas turbine, confirm the contract path and service scope in writing. Do not accept a rebadged unit if your financing or certification requires OEM traceability. This is the core of the wind turbine OEM vs private label question.
3. Use the official wind turbine catalog, not a scraped PDF
Third-party catalogs go stale. I pull the official product page and save a timestamped copy. For the Vestas V236-15.0 MW offshore wind turbine, Vestas lists it as a 15 MW offshore turbine with a 236 m rotor and 115.5 m blades. I accessed the Vestas product page in May 2026. Verify current specs there before you put anything in a tender.
Check the following in the catalog: nominal power, rotor diameter, blade length, swept area, cut-in and cut-out wind speeds, operating temperature range, grid frequency, and certification basis. If the catalog doesn't show the certification basis, request it.
4. Confirm type certification and grid-code compliance
A glossy spec sheet is not a type certificate. Ask for the IECRE certificate or equivalent type certification, design evaluation report, and grid-code compliance statement. For power quality, IEC 61400-21 is the reference I expect to see cited. For offshore, the certification path should cover the turbine and the support structure interface.
Why does this matter? Because a turbine that isn't certified for your market can become a stranded asset. I've seen projects delay financial close over a missing grid-code document, not over blade length.
5. Map logistics and installation before you negotiate price
Offshore wind is a logistics business. The V236-15.0 MW has a 115.5 m blade and a 236 m rotor. That affects vessel selection, port storage, crane capacity, and installation weather windows. Onshore, it affects road surveys, blade trailers, and laydown yards.
I ask three questions: Can the supplier deliver to the port or site? What handling equipment is required? Who owns the risk if the vessel or crane is late? If those answers are vague, the unit price is almost meaningless.
6. Review the service model and spare-parts chain
Don't buy a turbine and assume service is included. Get the service scope in writing: preventive maintenance, remote monitoring, spare-parts availability, technician training, and response times. I do not accept verbal promises about uptime. I ask for the contractual availability definition and the exclusions.
Here's the thing: a cheap turbine with expensive service can cost more than a higher-priced turbine with a clear service model. That's not a sales pitch. It's a cash-flow issue.
7. Compare total cost of ownership, not price per MW
It's tempting to compare turbines by price per MW. But that ignores logistics, foundations, installation, commissioning, service, financing, and downtime risk. I build a simple TCO table: base supply price, transport, installation support, commissioning, service contract, spare parts, and expected major maintenance.
In my experience, the lowest quote has cost us more in at least 60% of cases once you add the hidden line items. That $120k saving on a service contract can vanish with one unplanned crane call. So I score value, not just price.
8. Validate performance guarantees and contractual boundaries
No supplier should guarantee a specific energy output unless the contract is structured for it. Power curves are test conditions, not production promises. I ask for the warranted power curve, the measurement standard, the availability guarantee, and the liquidated damages formula.
For energy yield, I use an independent assessment from a firm like DNV or UL. I never take an ROI number from a catalog. If a supplier guarantees ROI, that's a red flag.
9. Run a reference and documentation audit
Ask for three to five comparable references. Check the project type, turbine model, site conditions, and commissioning date. Then ask for the documentation package: O&M manuals, safety manuals, lifting plans, spare-parts lists, and cybersecurity documentation.
If a supplier can't provide a complete document index, the project will leak time later. I've learned that the hard way on smaller component orders. On a turbine, the cost of missing documentation is much higher.
Common mistakes I see
- Comparing catalog specs without checking site class.
- Accepting a private-label unit when the financing requires OEM traceability.
- Treating the power curve as a production guarantee.
- Forgetting port, vessel, and crane constraints for offshore turbines.
- Leaving service scope and spare-parts availability vague.
- Choosing the lowest quote without a TCO model.
- Not verifying grid-code compliance before signing.
Before you send the RFP
Use the checklist as a gate, not a scorecard. If a supplier fails step 2 or step 4, stop. If they pass, move to technical and commercial negotiation. And keep dated copies of everything. Prices, certifications, and product pages change.
One more boundary: I've only worked on mid-size onshore and offshore procurement packages. If you're buying in a different regulatory market, your certification and tax structure may differ. Verify with your legal and engineering teams.
Vestas official product pages and IEC standards are the sources I start with. As of May 2026, the Vestas V236-15.0 MW remains a 15 MW offshore platform with a 236 m rotor and 115.5 m blades on Vestas' public catalog. Check current data before you rely on it.