Arctech owns the first Wind Tunnel laboratory located in our factory in Kunshan, China. Arctech together with CPP Wind Engineers performed extensive aeroelastic tests to characterize behavior of all Arctech’s trackers.
The most important wind tunnel result was the measure of flexures and creation of an instability map. This instability map plots the maximum deflection angle of a group of trackers at -2° and their critical wind speeds.
Critical wind speed (𝑼𝒄𝒓) is defined as the wind speed that causes an excessive rotation (deflection around the torque tube) of the PV modules on top. This is the speed measured at which the tracker has deflected 30º peak to peak, which is the maximum deflection that Arctech allows by design.
Wind stow speed: is defined as the wind speed limit at which the tracker will go to a stow position. Notice this wind speed is not the maximum windspeed your tracker design can withstand. Tracker usually operates below Wind Stow Speed and is considered as the tracker working windspeed. As shown above, the minimum critical windspeed is obtained at steep angles, we use that minimum wind speed plus a safe margin as trigger point to send trackers to stow.
Wind stow position: is defined as the tilt position where the minimum critical wind speed is higher and by that it is a safer position. It’s approximately to -2º.
Advice* All values given are for reference and may not be equal to your project setup. Your project may have different characteristics and requirements. Ask Arctech for the recommended parameters for your tracker.
NCU uses anemometers sensor to acquire real-time wind speed data at all times during normal operation mode. Once these anemometers detect a wind speed consistently higher than the threshold during specified amount of time, wind mode is triggered and trackers start moving into wind mode.
Wind Stow signal is triggered anytime the averaged measured wind speed (5.85@30s) is above “upper windspeed level” threshold (in m/s) parameter.
In order to do an automatic release of the Wind Stow Mode, two parameters are required, “Down wind speed level” threshold (in m/s) that indicates a bottom level and “Recover Time” (in seconds) to mark how long the signal shall remain below the “Lower wind speed level” before releasing wind mode.
The following parameters are available for setup. They can be set locally to a specific TCU (using Arctech Smart Tool), or can be broadcasted from NCU (using Arctech Solar Communication Control) to all TCU in the area.
Enable Facing Wind Stow:
EStowAngle[º]:
WStowAngle[º]:
The software of NCU uses Wind protection parameters:
Typical tracker speed move is 9º/min once the wind mode is triggered the tracker should reach safe stow position in less than 7min.
