Article: How standardisation can improve financing uncertainty in wind energy (3E)
As wind energy projects grow in scale and capital intensity, the robustness of energy yield assessments has become a critical concern for developers, lenders, and public authorities. Any deviation from actual performance can materially affect project financial viability.
General uncertainties on the end-result of energy yield assessments for example, lie within 8% to 14% depending on the project characteristics. While models improve over time, uncertainties remain significant.
An impact that is commonly underestimated however is the impact of the choice of the consultant and the applied methodologies on the end uncertainty, which is generally not something that is being quantified nor accounted for as usually considered embedded in the consultant’s own estimates.
To evaluate the differences of energy yield assessments between industry members and thereby evaluate the uncertainty solely related to the choice of the resource expert, the Danish Technical University (DTU) organised a proficiency test. In total, 28 participants (consultants and project developers), including 3E, submitted production estimates for the Walney 3 & 4 offshore wind farm with a rated capacity of 659MW.
The figure shows a clear spread across all submissions. While the standard deviation is relatively low (~3%), the gap between the most conservative and most optimistic results exceeds 10%, a range comparable to typical offshore energy yield uncertainty. This highlights the limitations of self-estimated uncertainty and the need for standardised, industry-proven methodologies.
To reduce uncertainty ranges, and to improve the consistency and comparability of results, the wind industry has established a suite of standards and methodological guidelines defining best practice for wind resource measurement and energy yield assessment. Prominent examples include the:
- IEC 61400-50 series;
- the MEASNET evaluation guidelines; and
- Germany’s FGW TR6 (commonly referred to as TG6).
Complementing these technical standards is a facilitating quality framework: ISO/IEC 17025, the international standard specifying requirements for the competence, impartiality, and consistent operation of testing and calibration laboratories. While IEC, MEASNET, and FGW define what should be done from a technical perspective, ISO 17025 governs how organisations demonstrate that these activities are executed under controlled, traceable, and quality-assured conditions.
From a project finance standpoint, this institutionalised quality assurance is particularly valuable: lenders and investors seek confidence not only in the methods applied, but also in the rigor and governance of the processes behind them.
As a result, ISO 17025 accreditation, specifically when scoped to relevant wind measurement and energy yield assessment activities, is increasingly referenced in tender specifications, lender technical advisor requirements, and regulatory frameworks across multiple markets.
Standardisation helps minimise these risks by ensuring that technical results are reproducible, traceable, and comparable.
3E is an international renewable energy consultancy and software company delivering technical advisory and analytics services across the full wind project lifecycle. The company recently obtained ISO/IEC 17025 accreditation, underscoring its commitment to standardised methodologies, measurement traceability, and data integrity in wind resource assessment.
Acting as an independent expert across a broad portfolio of projects and markets, 3E is routinely exposed to the full spectrum of industry practice: from exemplary implementations to installations where seemingly minor deviations from best practice can materially affect data quality. Experience shows indeed that wind measurement data used for site appraisal can vary considerably in reliability and consistency, depending on how rigorously standards are applied in the field, increasing uncertainty and, ultimately, project risk.
The relevance of accredited approaches extends beyond Europe. 3E has contributed technical expertise to projects developed under South Africa’s Renewable Energy Independent Power Producer Procurement Programme (REIPPPP), and the IFC’s Scaling Wind [2] and ESMAP programs where consistent application of standards and guidelines has been essential to support transparent project evaluation and attract international financing.
References:[1] Jake Badger, Dalibor Cavar, Morten Nielsen, Niels G. Mortensen, Brian O. Hansen (DTU Wind Energy), 15/09/2021, CREYAP 2021
[2] International Finance Corporation. (n.d.). Scaling Wind. World Bank Group.
