What this sector has to measure
Renewable energy is the sector where instruments are most often expected to work with nobody present. Sites are remote, spread out and frequently unmanned, so the measurement has to be autonomous, tolerant of weather and able to deliver its record over a link that may not be reliable. That single condition shapes more of the specification than the physical quantity being measured does.
The second characteristic is that the quantities are frequently used to support a performance claim rather than to control a process. Irradiation, wind speed and direction, energy output and performance ratio determine whether a plant is producing what it was predicted to produce, and a commercial dispute about output is settled with measurement evidence. That places the emphasis on calibration, sampling interval and completeness of the record rather than on response speed.
The third is the diversity inside the industry. A photovoltaic plant measures irradiation and inverter output, a wind farm measures wind with an availability requirement that has commercial consequences, a hydro plant measures flow and level, and a storage system measures current, voltage and battery temperature. Treating these as one instrumentation category is a mistake: what they share is the operating model, not the physics.
Where the instruments sit
Solar photovoltaic
Irradiation, module and ambient temperature, inverter output and delivered energy. These measurements establish the performance ratio, so calibration and completeness of the record matter as much as sensor accuracy.
Wind
Wind speed and direction, nacelle conditions, vibration and power output. Availability of the measurement has commercial consequences, and the instruments are exposed to weather continuously.
Hydro and biomass
Flow, level, pressure and temperature of the working fluid, plus the process instrumentation around a thermal plant. Media are frequently abrasive or corrosive, and the plant often runs unattended for long periods.
Energy storage and grid interface
Current, voltage, power, energy, temperature and the state of the battery system. These measurements are electrical and thermal, and they frequently feed both control and protection.
Instrumentation used in this sector
| Measurement | What is measured in this sector | Instruments commonly specified |
| Irradiation and weather | Solar irradiance, ambient and module temperature, wind speed and direction, rainfall and humidity | Pyranometers and reference cells, temperature sensors on the module and in the air, and wind sensors chosen for the exposure and for the maintenance interval the site can support |
| Flow | Working fluid in hydro and thermal plant, heat transfer fluid, cooling water and process water | Electromagnetic and ultrasonic meters for water and conductive fluids, and vortex or differential-pressure installations for steam and gas in a thermal plant |
| Level and pressure | Reservoirs, tanks, hydraulic circuits and cooling systems | Hydrostatic and radar transmitters, pressure transmitters with sealing suited to the medium, and switches for protection where a level excursion has a cost |
| Temperature | Module and ambient temperature, battery and inverter temperature, bearings and gearboxes, and process temperature | RTDs and thermocouples for surface and process measurement, and non-contact measurement for rotating or inaccessible parts |
| Electrical | Voltage, current, power, energy, power quality and insulation state | Power meters and analysers for the grid interface, insulation testers for maintenance, and acquisition channels rated for the system voltage and waveform |
| Vibration and condition | Turbine, gearbox and rotating machinery vibration | Accelerometers and proximity measurement, frequently connected to a condition monitoring system because the site is unmanned |
The operating model matters as much as the physics here. Power available at the measurement point, remote access and the maintenance interval should be stated with the measurement itself.
How to specify for a renewable energy site
- Power available at the measurement point, first, because a site with no supply changes the entire specification and forces a choice between batteries, a small local supply and local logging alone.
- How the record reaches the operator - a physical visit, a radio link or a cellular connection - since an unreliable link has to be planned for rather than discovered after installation.
- Whether the measurement supports a performance claim or a commercial settlement, because those require calibration, completeness and an auditable record rather than merely a working sensor.
- Exposure: wind, salt, dust, temperature range and precipitation, all of which decide the enclosure and the mounting more than the sensor does.
- The maintenance interval the site can support, which is the practical limit on anything needing cleaning, recalibration or a consumable.
- Sampling interval and record length, which together set the memory and the power requirement and are frequently underestimated at the planning stage.
- Whether the measurement feeds protection as well as control, because a protective function requires independence and a defined behaviour when it fails.
- The system voltage and waveform at the electrical measurement, since the instrument class follows from those rather than from the nominal power rating.
Standards and approvals that may apply
- Grid connection and power quality requirements applied by the network operator, which define the electrical measurements and the record.
- Performance and resource assessment standards referenced in the commercial agreement, which fix the measurement method for irradiation or wind.
- Electrical safety requirements for the system voltage involved, including any requirements specific to direct-current systems.
- Environmental and planning obligations, where noise, ecological or visual monitoring may be required in addition to the plant measurements.
- We describe what an installation may have to meet. We do not claim that an approval is held for a product unless the certificate has been supplied to us, and the product pages follow the same rule.
Applications in this sector
