Zelya Energy

Looking to acquire, insure, or optimize the performance of a wind farm?

Zelya Energy Experts, conducting wind turbine technical audits

Our teams perform ad hoc audits of parks and comprehensive due diligence. They also support operational activities with solutions and real-time optimization applications for wind turbine performance. 

  • analysis of operating, and curative and preventive maintenance reports
  • modeling the guaranteed availability rate and failure probability
  • on-site visit and assessment of the actual condition of mechanical, electronic equipment...
  • real-time feedback of key production information
  • extremely advanced web analysis applications for production, allowing to identify fragile equipment in real time and to explain the origins of alarms and shutdowns

Our team audits and supports several hundreds of megawatts in project or in operation every year.

Our understanding of how markets operate and our detailed knowledge of the profitability issues of renewable assets allow us to provide comprehensive solutions, meeting operational needs on the ground as well as managerial and financial requirements at head office level.

Our due diligence services

Wind farm technical due diligence

Study of electricity grid connection conditions

Audit of the actual condition of the equipment

Performance and failure risk study

Operational support services

Study of power increase possibilities

Production and performance monitoring dashboards

Services related to the closing

Full technical inventory

Zelya Energy Experts, wind technical due diligences

Technical due diligence


Technical due diligence is a complement to regulatory due-diligence. It validates general technical characteristics and quantifies uncertainties and risks related to quantities forecasted for a wind farm or portfolio.

More specifically, it aims to :

identify potential inconsistencies between sizing and production, operation and maintenance conditions

validate the general technical characteristics of the farm or portfolio: resource, losses, performance, availability, production

quantify uncertainties and risks that could negatively impact these technical characteristics;

prescribe realistic assumptions for these technical characteristics for the financial valuation model;

recommend, list and prioritize appropriate conditions precedent in the context of a purchase offer

Content / Steps

To evaluate the production to be considered and quantify the uncertainties and risks of its value, we proceed to the following tasks :

collection of relevant documents: equipment supply contracts, operation and maintenance, insurance, connection and access to networks, resource study and production, etc

Technological analysis and evaluation of the overall sizing of equipment

review of resource and production study

analysis of technical clauses of contracts: performance, raw, guaranteed and insured availability and production

See related services below

Assistance with electrical connection of wind farms

Study of technical conditions for connection to networks


The study of the technical conditions for connecting a farm or a wind portfolio to electricity transport or distribution networks is a complementary part of the technical due diligence.

It is required when it is necessary to examine more specifically and in detail if the connection is optimized from a technical and electrical point of view (acceptable level of line losses up to the delivery point, reasonable grid unavailability rate and reductions, ... ), and more generally, if the sizing and operating conditions of the internal electrical installation comply with that of the connection to the electricity networks.

More specifically, it aims to :

identify possible inconsistencies between the sizing and operating conditions of the internal installation and the connection infrastructure

validate technical characteristics of the connection

quantify uncertainties and risks that could negatively impact the wind farm's production

prescribe realistic assumptions for these technical characteristics for the financial valuation model

recommend, list and prioritize appropriate conditions precedent or possible improvements

Specific case of a projected wind farm / Steps

For a projected wind farm or wind portfolio, it is possible to complete the analysis of the only generally available documents (connection studies, technical and financial proposal) by a prospective analysis of the foreseeable connection agreement, operation agreement, and network access contract, given the current regulation

See related service: Optimization and negotiation of conditions for connection to electrical networks

Zelya Energy Experts, audits, visits on wind sites, equipment diagnosis

Audit of the actual condition of the equipment


The audit of the actual condition of equipment of a wind farm or a wind portfolio in operation is a complement to technical due diligence.

It allows to verify that the mechanical, electrical, hydraulic equipment is in good working and maintenance condition and to establish, where applicable, a list of measures to be taken and replacement equipment to be stored

More specifically, it seeks to :

take an inventory of installed equipment

qualify the actual state of the mechanical, electrical and hydraulic equipment and their maintenance

quantify their expected lifespan for the financial valuation model

identify measures to be taken before or after the transaction

recommend, list and prioritize the appropriate conditions precedent: replacement measures to be taken, equipment to be made in stock...

Content / Steps

The opportunity and scope of the technical audit of a farm or portfolio in operation can be decided based on the results and recommendations of the technical due diligence, the performance study and the warranty and maintenance study.

In particular, depending on these results, visual inspection and certain specific tests can be targeted on a sample of machines only (infrared, gearbox endoscopy, vibration analysis, isolation test,...)

The on-site audit by visual inspection typically covers the blades, the HV and LV cabinets, the generator, the power electronics, and the gearbox. Other specific tests are performed.

Wind turbine technical expertise and alarm and failure analysis

Performance and risk of failure study of an operating park


The study of the real performance of a wind park or a wind portfolio in operation is a complement to technical due diligence.

Its purpose is to identify the reasons for the sub-optimization of production given the operating conditions and, in particular, to quantify the impact of maintenance operations on the availability of the wind park, and thus, to verify whether the conditions of maintenance and the guarantees subscribed are optimal.

More specifically, it aims to:

estimate the real guaranteed and non-guaranteed unavailability of each machine and the park as a whole

identify the origin of unavailability

make recommendations on the values of real technical characteristics to be considered in the financial evaluation model

make recommendations on the machines that could usefully be subject to a technical audit on site and control tests

analyze the relevance of the warranty perimeter and the level of guaranteed availability per machine and for the park as a whole.

Content / Steps

The study of the real performance of a wind park or a wind portfolio in operation requires the following tasks:

Collection and analysis of relevant documents: production, operation and maintenance reports, maintenance contracts and protocols, list of failure codes, etc.

Estimation of real site resource characteristics, gross unavailability rate by origin

Analysis of the occurrence and duration of preventive and corrective maintenance operations by machine

Verification of the effectiveness and relevance of corrective maintenance operations given the type of failures observed, as well as the opportunity and consistency of preventive maintenance operations given operating conditions (wind speed)

Simulation of the actual power curve and estimation of actual producible, yield and actual annual operating hours

Comparative analysis of the real characteristics of the wind park with those provided by the equipment manufacturer or estimated in the site resource and producible study.

Wind management and alarm analysis application information

Our applications dedicated to wind aim to monitor and improve the performance of wind turbines

They provide dashboards updated in real-time, including:

the availability rate of each turbine and wind park,

fundamental technical parameters of equipment (oil, temperature, sound),

the origin and occurrence of stops and their associated losses,

the theoretical production that each turbine should and could have reached...

Furthermore, our platforms and applications are:

Responsive and accessible from smartphones, tablets, and computers,

Integrated, designed to be usable and understood by different departments: technical, management, finance,


Customizable: analyses can be targeted on specific days or months with one click,

Exportable: graphs, data tables, and images can be exported and shared in various formats such as jpg, xls, pdf.

More information is available here


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