The stow strategy is a key contributor to avoiding wind-related failure of a tracking system. At the same time, it also governs how much material must be implemented in a structure at a particular site. In our latest Whitepaper it is shown that the safest tilt angle for stow is 0° if combined with intelligent load transmission or mechanical locking, high natural frequency and high damping ratio.
Moreover, the 0° stow position leads to enormous material savings in the structure and provides the best protection of photovoltaic modules against damages such as micro cracks in cells as well as back sheet and glass defects through sandblast abrasion. This is of prime importance since the modules are the highest invest of a solar plant.
Stowing flat is also easy to achieve by use of just one inclination sensor. In addition, the 0° stow position is not vulnerable to changes of wind direction as opposed to tracking systems which rely on stow at a high tilt angle without being designed for the full compass of wind directions. Another source of uncertainty of such high-tilt stow strategy may be the measurement of wind direction.
Last but not least, it is important to note that not every single-axis tracking system is safe at 0° stow position. Owners, EPCs and other project stakeholders should closely monitor the combination of torsional stiffness, natural frequency, and damping ratio that is to ascertain the aerodynamic stability of market-type systems at operational and design wind speeds.