Anemometers are instruments that measure wind speed. Users can employ it in different installations, like for example for the management and monitoring of wind farms, weather stations, photovoltaic plants, ski lift, highways, viaducts, high routes & airports. In most applications, users equip anemometer with anti-icing system.
TYPES OF ANEMOMETERS
Based on the operating principle they are divided into the following types:
Vane anemometers (mechanical principle of 3 rotating ‘spoons’ around a vertical axis);
Ultrasonic anemometers (speed of sound waves propagation influenced by air motion);
Hot wire anemometers (measures the cooling rate of a hot wire).
Depending on the output signal, we can distinguish into the following types:
USES OF THE ANEMOMETER IN THE PHOTOVOLTAIC INDUSTRY
In the photovoltaic industry, anemometers are installed for the following purposes:
For uses provided by the Standard EVS-EN 61724-1 (Photovoltaic system performance – Part 1: Monitoring)
In PV systems with a solar tracker system, user need to be bring the solar tracker system into a safe position in the presence of wind gusts exceeding a given threshold detected by the anemometer.
To assess the increase in production caused by the wind considering that:
Wind increases the cooling of PV modules and this leads to an increase in their efficiency.
The wind generally carries away particulates suspended in the atmosphere, which reduces the solar radiation reaching the earth’s surface.
Wind generally affects the humidity of the air, which has a negative influence on the solar radiation reaching the earth’s surface.
Frequently, users add wind direction indicator or vane meter to the anemometer. This is a ‘wind vane’ that marks the direction from which the wind comes. By relating the output data with module temperature, wind speed and direction, it is possible to understand from which directions the driest, wettest or coolest winds come, etc.
Connection to the Monitoring System
The way the anemometer is connected to the monitoring system depends on its output type:
Anemometers with digital output These can be connected directly to the datalogger, which reads and records the wind speed values through its digital communication interface (for example via RS-485/Modbus, Ethernet, or other supported protocols).
Anemometers with pulse output Anemometers that provide a pulse output (each pulse corresponding to a certain wind speed increment) can be connected directly to a Sunmeter (PV reference cell) and then from the Sunmeter to the datalogger, as shown in the figure. In this configuration, the Sunmeter acquires both:
the irradiance from the PV cell, andthe wind speed from the anemometer,
and forwards the combined data to the datalogger. This allows the monitoring system to record irradiance and wind data through a single device, simplifying wiring and integration.
For detailed electrical characteristics, wiring diagrams and installation limits, please refer to the datasheets of the corresponding products in the product section.
