Understanding how lenders evaluate wind energy yield assessments is crucial for developers seeking project financing. This guide explains the key criteria and common concerns that lenders and their technical advisors (LTAs) assess during due diligence.
What Lenders Look For
1. Independent Assessment
Lenders require assessments from independent consultants with no ties to the developer, turbine manufacturer, or project. This independence ensures objective findings. An assessment prepared by the developer's own engineering team, or by a consultant with existing turbine supply contracts, will not be accepted without significant qualification.
2. Methodology Transparency
Clear documentation of all methodologies, assumptions, and data sources is essential. Lenders or their technical advisors must be able to audit the complete analytical chain — from raw met mast data through long-term correction (MCP), wind flow modelling (WAsP, WindPRO, Openwind, or CFD for complex terrain), wake modelling, and gross-to-net loss derivation. Any black-box step is a red flag.
3. Uncertainty Analysis
Comprehensive quantification of all uncertainty sources is critical. Lenders use P90 estimates for debt sizing, so understanding what drives the P50-to-P90 spread is essential for DSCR calculations. Under-stated uncertainty — particularly around long-term correlation quality or inter-annual variability — is a frequent trigger for LTA pushback.
4. Measurement Campaign Quality
High-quality on-site measurements are strongly preferred. Lenders assess:
- Measurement campaign duration — typically minimum 12 months; 24+ months preferred
- Sensor calibration records and traceable calibration certificates
- Data recovery rate — typically >95% expected
- Correlation quality with long-term reference (ERA5, MERRA-2, or regional stations)
- Measurement height relative to proposed hub height
- Representativeness of the mast location relative to turbine positions
Common Red Flags
Lenders' technical advisors look for issues that may indicate problems with the energy case:
- Unusually low uncertainty estimates relative to the measurement campaign length
- Limited on-site data with aggressive long-term correction claims
- Aggressive loss factor assumptions (availability, wake, electrical)
- Lack of sensitivity analysis on key assumptions
- Incomplete or inconsistent documentation
- Wake model choice inconsistent with site terrain or layout density
- Extreme wind analysis based on inadequate observational records
Best Practices for Developers
To ensure your assessment meets lender requirements:
- Engage independent consultants early — before the measurement campaign design, not after
- Invest in quality on-site measurements with calibrated anemometers and wind vanes
- Use multiple long-term reference datasets (ERA5 and MERRA-2) for cross-validation
- Request transparent methodology documentation with reproducible intermediate outputs
- Include comprehensive sensitivity analysis on the main uncertainty drivers
- Address potential concerns proactively rather than waiting for the LTA review