Site assessment

We accompany your project from the first energy yield estimation to wind measurements up to the final bankable wind study as a basis for your financial considerations. Depending on the site-specific characteristics, anemos has the possibility of using different kinds of flow models for energy yield calculations to reasonably simulate the wind conditions at your site. For sites in complex terrain we use CFD simulations.

Whether for the long-term correlation of wind measurements or energy yield data of reference turbines or to drive the flow models - the data of our wind atlases are applied in every wind study as additional information. Hereby, we reach the high accuracy of our energy yield calculations.

The reports are prepared according to the Technical Guideline TR 6 which defines the high-quality standards of German site assessment studies and according to the international IEC guidelines.

If your first estimate does not need to comply with TR 6, the initial estimation based on wind atlases is sufficient.

According to the EEG 2017, the quality of the wind turbine sites which are approved after 1.1.2017 and are not subject to exceptions, must be determined for commissioning and verified after 5, 10 and 15 years. The site quality index is the ratio of the turbine-specific energy yield, taking into account certain losses (site energy yield) and the reference yield of the corresponding WTG type.

The site energy yield for commissioning is equal to the gross energy yield minus loss factors. These include wake losses, losses due to technical unavailability, electrical efficiency losses and losses due to environmental restrictions. The 10-minute time series of the anemos Wind Atlas are particularly valuable for these losses.

The site quality index has to be proved by an accredited expert according to the guidelines of the FGW (Association for Wind Energy and other Renewable Energies). anemos is one of the first companies accredited for the determination of the site quality index for commissioning.

anemos has actively participated in the discussion and the formulation of the corresponding guidelines. The determination of site quality index for commissioning is based on a site assessment study. We also carry out the determination of site quality after commissioning after 5, 10 and 15 operating years.

Moreover, we create maps of site quality index (Germany) with the highest possible spatial resolution.

The calculation of losses is a major part within a wind and energy yield study. In addition to daily shutdowns and curtailments, annual and weather related restrictions are required for the licensing.

anemos is using high-resolution 10-minute data of the anemos Wind Atlases to calculate the energy losses. These data consist of 20 years of site-specific meteorological data providing information about the wind potential and energy yield. An accurate prediction of the losses for the future operation time can be achieved. Various restrictions may occur at the same time. Our time series analysis guarantees the consideration of simultaneous restriction events to avoid double rating.

Examples of possible restrictions are:

• shutdowns and curtailments due to noise issues
• shutdowns to avoid shadow impact
• shutdowns to protect the avifauna (i.e. bats, cranes, breeding seasons, etc.)
• sector management to reduce mechanical loads
• shutdowns due to ice accumulation

Licensing procedures for wind turbines are based on reports about the calculation of noise immission.

We calculate the noise immission using the module NOISE of the program package WindPRO by EMD International A/S according to the DIN ISO 9613-2 of the “Deutsches Institut für Normung e.V.” and the “Hinweise der Bund/Länder-Arbeitsgemeinschaft Immissionsschutz (LAI)”, as of 30.05.2016 and the demanded interim procedure for noise propagation calculation of the “NALS”, version 2015-05.1, respectively and according to the "TA Lärm" (1998). State specific regulations are considered if necessary. The corresponding yield is calculated by reducing time-dependent adaptation of the performance characteristic.

During the preparation of a noise immission report, we are in direct exchange with the licensing authorities.

We generate a yield estimation for the location of your small wind turbines, based on our anemos D-3km Atlas.

It is also possible to determine the wind potential on the basis of your wind measurement.