The yield is down.
One wind speed cannot tell you why.
Three-axis and research-grade anemometry for wake interaction, terrain-driven shear and flow inclination, so an underperformance argument is made from measurement rather than from a model.
Underperformance is easy to see and hard to attribute
A site that generates below its assumption produces an immediate commercial problem and no immediate explanation. The shortfall is visible in the revenue and invisible in the SCADA wind speed, because the nacelle anemometer sits behind the rotor that is causing part of the effect.
Wake interaction between rows, terrain-driven shear and flow inclination all reduce yield, and they reduce it differently at different times of day and in different stability conditions. A single horizontal wind speed averages all of that into one number that explains nothing.
Without measurement, the conversation between owner, operator and turbine supplier becomes a comparison of models. Each party has one, and each model was built on assumptions the others did not make.
Every renewable decision starts at a measurement point
A renewable site measures across the whole asset. Wind at the nacelle and on the mast. Turbulence and shear across the rotor. Irradiance across the array, ambient at the substation, and the condition of the machinery below.
Nacelle-mounted wind sensor
Yaw and pitch are set from the nacelle reading, so an error there is not a data problem, it is lost yield on every hour the turbine runs.
- WindObserver 75 turbine-control accuracy 1 percent within 25 degrees of datum
- WindObserver 90 0 to 90 m/s where the site sees extreme gusts
- WindSonic M heated aluminium, operating to -40 degrees C
Met mast at hub height
The hub-height reading is the reference the whole power curve is argued from, and it has to survive a decade on a mast nobody climbs lightly.
- WindObserver 75 316 stainless open head, no moving parts, IP66
- WindMaster Pro 3-axis to 32 Hz for turbulence intensity
- MetConnect THP adds air density from temperature, humidity and pressure
Lower mast levels and the shear profile
Wind shear across the rotor is what turns a good site into a marginal one, and you only see it by measuring at more than one height.
- WindObserver 70 heated head for a second and third measurement level
- WindSonic 60 0.5 kg, low cost per additional level
- MetConnect THP WMO-compliant separation of sensors by height
Blade pitch and yaw position feedback
Pitch and yaw actuators run millions of cycles across a turbine life, and a position sensor with contacting parts is a scheduled failure.
- Blade position sensors non-contact inductive, linear and rotary
- Blade60 contactless linear position feedback
- Blade360 contactless rotary position feedback
Gearbox and main bearing condition
A gearbox failure means a crane, a weather window and weeks of lost generation. The wear shows up in the oil long before the vibration.
- WearDetect oil debris sensing for ferrous wear particles
- WearDetect with display local indication alongside the output
- LevelPro lube and hydraulic level with no moving parts
Hydraulic and lubrication fluid level
Level in the tower base is checked on a service visit, which on a remote site can be months apart.
- LevelPro capacitive level sensing, no moving parts
- LevelLite level measurement for smaller reservoirs
- DD1615 level display local display for the level output
Substation and grid connection
Transformer ratings derate with ambient temperature, so the substation needs its own measurement rather than the site average.
- MaxiMet GMX500 wind, temperature, humidity and pressure in one unit
- MetConnect THP accepts Pt100 and analogue inputs from existing kit
- WindSonic 60 a local wind reference for the compound
Solar array irradiance and soiling
Performance ratio is only meaningful against measured irradiance, and a soiling loss you cannot see is a soiling loss you do not clean.
- MaxiMet GMX301 solar radiation only, 0 to 1600 W per square metre
- MaxiMet GMX551 wind, T, H, P, solar and rainfall in one station
- MaxiMet GMX501 wind, T, H, P and solar without rainfall
Battery storage containers
Battery containers are rated on ambient temperature and airflow, and derating on a hot still day is a commercial event, not a technical one.
- MetConnect THP temperature to 0.2 degrees C, humidity to 1.5 percent RH
- MaxiMet GMX300 temperature, humidity and pressure, no wind
- WindSonic 60 airflow reference at the container face
Control building and SCADA
The measurement is only useful once it is inside the system that acts on it, in the protocol that system already speaks.
- MetConnect One Modbus RTU and ASCII, SDI-12 v1.3, NMEA 0183
- WindObserver 75 RS422 and RS485, Modbus RTU variant available
- MaxiMet GMX551 one cable, one output string into the logger
Crane pads and construction lifts
A nacelle lift stops at a defined wind speed. The argument afterwards is always about what the wind actually was.
- WindSonic 75 0 to 75 m/s, full-range accuracy published
- WindObserver 90 0 to 90 m/s for exposed lifts
- MaxiMet GMX200 wind only, 0.5 kg, for a temporary works mast
Turbulence and wake effects
Wake losses across a row are the difference between the yield model and the revenue, and measuring them needs the vertical component.
- WindMaster Pro 3-axis, 32 Hz, 0 to 65 m/s, stainless steel
- WindMaster 3-axis to 20 Hz with a 32 Hz option
- R3-50 50 Hz research-grade 3-axis for detailed studies
Icing and cold-climate operation
An iced cup anemometer reports a false calm, and a turbine that trusts it stops earning while the wind is still blowing.
- WindObserver 75 heated head, icing tested to MIL-STD-810F
- WindSonic M heated aluminium body, operating to -40 degrees C
- WindObserver 70 heated, operating to -55 degrees C with heating
Precipitation and site conditions
Rainfall matters for erosion, access and soiling, and on a remote site the maintenance burden of the gauge matters as much as its accuracy.
- TruMet PW100 optical, 0 to 200 mm/hr, no moving parts to block
- MaxiMet GMX551 rainfall alongside wind, T, H, P and solar
- MetConnect THP contact-closure input for the TruMet pulse output
Site assessment and pre-construction survey
The measurement campaign that sets the yield assumption is the single most expensive number in the project, and it is taken years before revenue.
- WindMaster Pro 3-axis for turbulence intensity and flow inclination
- WindObserver 75 the long-duration reference on the mast
- MetConnect THP air density from temperature, humidity and pressure
Calibration and verification
A power curve warranty is argued from measured wind. Traceable calibration is what makes that measurement admissible.
- UKAS-accredited air velocity calibration traceable certification for anemometers
- Multi-parameter calibration six parameters, equipment from any manufacturer
- Recalibration scheduling intervals, reminders and turnaround
Three quantities that a 2-axis instrument cannot separate
Turbulence intensity describes how much the flow varies around its mean. It drives the fatigue loads the machine is certified against, and it rises sharply inside a wake. A cup anemometer averages that variation away, which is precisely the information needed.
Flow inclination is the angle of the wind to the horizontal. Over complex terrain it can be several degrees, and a rotor meeting inclined flow is not meeting the wind the power curve assumes. Only a three-axis measurement resolves it.
Wake deficit is the speed reduction downstream of a machine, and it recovers over distance in a way that depends on the turbulence of the inflow. Measuring inflow and downstream conditions at the same time is what turns a wake model into a wake observation.
These are measurement problems rather than analysis problems. The instrument decides whether the quantity exists in the dataset at all.
Sampling rate decides what is visible
Turbulence structure exists at frequencies that a slow instrument simply does not see. The sampling rate sets the smallest eddy the record contains, and anything faster than that becomes noise on the mean.
WindMaster provides 3-axis measurement at 20 Hz with options up to 32 Hz, which suits operational turbulence and shear work. The Research range provides 50 Hz on R3-50 and HS-50, and 100 Hz on R3-100 and HS-100, all at 14-bit resolution, for flux-style and boundary layer measurement.
Resolve the flow, do not average it
View the Research rangeThe instrument disturbs the flow it is measuring
Any anemometer head sits in the air it is measuring, so the geometry of the head decides how much of the flow it distorts and from which directions. For turbulence and flux work that distortion is not a rounding error, it is part of the result.
The Research range offers a standard head on R3-50 and R3-100, and a horizontal head on HS-50 and HS-100 where the flow direction and the mounting arrangement make that geometry the better choice. Choosing between them is an application decision worth making before the mast is designed.
Geometry chosen for the flow, not the bracket
Compare wind sensorsAn underperformance claim is only as good as its instrument
Availability warranties, power curve tests and underperformance claims all turn on measured conditions. The question asked is always the same: which instrument, sited where, calibrated when, and traceable to what.
An operational reading with no calibration history behind it is an assertion. The same reading from an instrument on a traceable interval is evidence, and the difference costs nothing at specification and a great deal afterwards.
Labcal is an independent UKAS-accredited laboratory operating to ISO/IEC 17025:2017, calibrating equipment from any manufacturer, which matters when the mast, the nacelle and the reference instrument came from three different suppliers.
What a turbulence campaign carries
Three-axis and research-grade anemometry for the flow itself, with the supporting meteorology and the accredited calibration behind both.
Three-axis measurement
Research range
50 Hz and 100 Hz 3-axis anemometers
For flux-style measurement and boundary layer work, where the sampling rate and the head geometry both form part of the result rather than part of the specification.
WindMaster
3-axis ultrasonic anemometer
The broader three-axis platform for turbulence intensity, flow inclination and shear across an operating site, in research, engineering, control and OEM applications.
WindObserver
Heated 316 stainless 2-axis anemometer
For the reference and boundary measurements around a turbulence campaign on a severely exposed or coastal site.
Supporting measurement
MetConnect
Separable sensors for WMO-compliant siting
Shear and stability work needs sensors at several heights and usually needs third-party instruments brought into the same station.
MaxiMet
All-in-one weather station, no moving parts
One unit and one output string for the supporting meteorological record beside the three-axis measurement.
WindSonic
Lightweight 2-axis ultrasonic anemometer
For the horizontal reference levels on a profile mast, where speed and direction are what the shear calculation needs.
Where turbulence and wake measurement does the work
Row-to-row wake
Measuring the deficit and recovery between rows, so array efficiency is observed rather than modelled.
Shear and inclination
Sites where the flow arrives at an angle and the power curve assumption quietly stops applying.
Contractual measurement
Reference measurement for performance verification, where the instrument and its calibration are part of the contract.
Before the larger rotor
Understanding the real inflow across the swept area before committing to a machine that reaches further into it.
External wake
Quantifying the effect of a new array upwind, where the argument will be commercial and needs measurement behind it.
Boundary layer and flux
Atmospheric measurement at 50 Hz or 100 Hz alongside the operational record.
UKAS-accredited calibration for six measurement parameters
Labcal is an independent UKAS-accredited calibration laboratory, Lab 0625, operating to ISO/IEC 17025:2017. It provides calibration across gas and air flow, air velocity, liquid flow, pressure, temperature and humidity.
For a turbulence campaign carrying anemometers, thermal probes, pressure instruments, temperature and humidity probes and data loggers, one accredited laboratory keeps a mixed installation on a single traceable schedule.
Gas meters · Mass flow controllers · Dispensing systems
Anemometers · Pitot tubes · Thermal probes
Flow meters and sensors · Process control equipment
Gauges · Transducers · Manometers · Transmitters
Thermometers · Probes · Thermocouples · Data loggers
Hygrometers · Probes · Transmitters
Getting high-rate data off a mast and into analysis
A turbulence measurement produces far more data than an operational wind reading, and it has to arrive intact and time-stamped consistently across every instrument on the mast.
Gill supports environmental monitoring, industrial sensing, embedded electronics and systems integration, so operators, consultants and research groups can bring high-rate measurement into acquisition chains, loggers and analysis pipelines.
Whether the requirement is a digital output feeding a research acquisition system, Modbus into a site network, or analogue into an existing logger, Gill engineers can support integration from specification through commissioning.
Outputs and options
- Digital output : Research acquisition chains at 50 Hz and 100 Hz
- Modbus RTU : Site systems and SCADA
- Analogue & serial : Existing logger channels
- Traceable calibration : So the record holds up on review
What the specification looks like in practice
Three axes, so the quantity exists
Flow inclination and the vertical component of turbulence are measured rather than inferred, which is what separates an observation from a model output.
Rate chosen for the question
WindMaster provides 20 Hz with options up to 32 Hz, and the Research range provides 50 Hz and 100 Hz at 14-bit resolution.
Head geometry as a specification item
A standard head on R3-50 and R3-100, and a horizontal head on HS-50 and HS-100, so the instrument suits the flow rather than the bracket.
Nothing rotates, so nothing seizes
No rotating sensing element to ice, foul, wear or seize, which is the failure mode that quietly biases a long campaign.
Built in the UK since 1985
Ultrasonic wind measurement designed and manufactured in Lymington, with the engineering team reachable during specification.
Evidence when the claim is tested
Independent UKAS-accredited calibration across six parameters, for equipment from any manufacturer, so a mixed campaign sits on one traceable schedule.
Questions about turbulence and wake measurement
Because it sits downstream of the rotor it is mounted on, so it reads flow that the machine has already disturbed. It is a control input rather than a measurement of the inflow.
Understanding a wake needs measurement of the undisturbed inflow and of conditions downstream, which means instruments on masts rather than on nacelles.
WindMaster is the broader 3-axis platform for research, engineering, control, marine and OEM applications, providing 20 Hz with options up to 32 Hz, and 32 Hz on WindMaster Pro and WindMaster HS.
The Research range is for work that needs 50 Hz or 100 Hz output and individual calibration. R3-50 and HS-50 operate at 50 Hz, R3-100 and HS-100 at 100 Hz.
Whenever the instrument distorting the flow would change the result, which is most turbulence and flux work. The Research range offers a standard head on R3 and a horizontal head on HS, and the choice depends on the flow direction and the mounting arrangement.
It depends on the scales the work needs. Operational turbulence intensity and shear are generally served by 20 Hz to 32 Hz. Flux-style and boundary layer measurement is where 50 Hz and 100 Hz become relevant.
Over complex terrain the flow can arrive at a measurable angle to the horizontal, and a rotor meeting inclined flow is not meeting the conditions the power curve assumes. Whether it matters on a given site is a measurement question rather than a general one.
Yes. Labcal is an independent UKAS-accredited calibration laboratory, Lab 0625, operating to ISO/IEC 17025:2017, and it calibrates equipment from any manufacturer across gas and air flow, air velocity, liquid flow, pressure, temperature and humidity.
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