Wind tunnel testing in PV mounting structure design. Why go beyond standard assumptions?
Wind tunnel testing allows engineers to analyse more precisely how wind interacts with the mounting structures of a utility-scale PV plant. This makes it possible to identify which areas of a project require additional reinforcement and where the same structural parameters are not necessary. For investors, this means a mounting structure better matched to the specific site, greater design precision and more efficient use of materials and project capital.
Favourable conditions do not mean there is nothing left to optimise
Not every solar farm is built on challenging terrain or under demanding geotechnical conditions. A good example is one of ENSON’s projects near Czerniewice, Poland. The project has a total capacity of 38 MW.
From a structural engineering perspective, the site conditions are highly favourable:
- flat terrain,
- favourable geotechnical conditions,
- relatively low wind and snow loads,
- conventional driven-pile foundations,
- a proven 2V2 mounting structure.
In other words, this is the kind of project structural engineers like to work with. But projects like this also show that optimisation is not only relevant when the ground conditions are difficult, the terrain is steep or environmental loads are particularly high. Even with a very good starting point, it is worth analysing more closely how the structure will perform at the specific site.
Eurocodes provide the foundation. Wind tunnel testing allows us to go further
PV mounting structures are designed in accordance with applicable standards, including the Eurocodes. These standards provide the framework and requirements used to account for factors such as wind loads, snow loads and other actions relevant to structural safety. Wind tunnel testing does not replace these standards. It provides an additional layer of information that allows engineers to model the interaction between wind and a specific solar farm layout more precisely. This matters because a large PV plant does not behave as one uniform structural system.
Loads may be influenced by factors including:
- the position of a structure within the solar farm,
- differences between perimeter and interior zones,
- the geometry of the overall layout,
- module height and tilt,
- interaction between adjacent rows,
- local terrain conditions.
Wind tunnel testing allows these relationships to be reflected more precisely in the structural design.
Not every part of a solar farm requires the same structural parameters
This is one of the key reasons why we look at a project in greater detail rather than applying one set of load assumptions across the entire site. Structures located in different areas of a solar farm may be exposed to different conditions. Some zones may experience higher loads and require additional reinforcement. In others, there may be no technical need to apply the same structural parameters.
This allows engineers to:
- increase structural capacity where it is actually required,
- select profiles and components more precisely,
- avoid unnecessary overdesign,
- maintain the required level of safety and long-term durability.
The objective is not to minimise the amount of steel. It is to design the structure around the conditions in which it will actually operate.
What does this mean for the investor?
The wind tunnel test result itself is only part of the value. What matters is how the data is translated into the final structural design.
Greater design precision
Instead of applying one set of assumptions across the entire solar farm, the structure can be adapted to differences between individual zones of the project.
Lower risk of unnecessary overdesign
If a particular area does not require additional reinforcement, there is no need to design it to the same parameters as the most heavily loaded zones. This allows material to be used where it is actually needed.
Better CAPEX control
The amount of material used has a direct impact on the cost of the mounting structure. More precise structural design can therefore support better control of project CAPEX without compromising the required level of safety or durability.
Better information for design decisions
Wind tunnel testing provides engineers and investors with additional information on how the structure is expected to perform at a specific site. This allows decisions to be based on a more detailed analysis rather than on averaged assumptions applied across the entire project.
38 MW near Czerniewice. What did the aerodynamic analysis change?
For ENSON’s 38 MW project near Czerniewice, the initial site conditions were very favourable. Even so, we used wind tunnel testing to analyse the distribution of wind loads across the solar farm in greater detail. This allowed us to differentiate the structural requirements for individual areas of the project and adapt the design accordingly. Where the loads were higher, the structure required additional reinforcement. Where additional reinforcement was not necessary, unnecessary overdesign could be avoided. As a result, the mounting structure was designed around the conditions of the specific site instead of treating the entire 38 MW project as one uniform structural system.
Optimisation does not mean designing the lightest possible structure
In PV mounting structure design, optimisation is sometimes reduced to one idea: using less steel. That is an oversimplification. A well-designed structure should be neither unnecessarily overdesigned nor engineered with the objective of minimising material at all costs. It should match the actual requirements of the project. In one area of the solar farm, this may mean additional reinforcement. In another, it may mean that the same level of reinforcement is simply not required. The objective remains the same: safety, durability and the most precise possible match between the structure and the conditions of the project.
Mindful Design: engineering for a specific project
At ENSON, this approach is part of our Mindful Design philosophy.
Each project is analysed in the context of its specific location: wind and snow zones, geotechnical conditions, terrain, module specifications and the requirements of both the investor and the EPC contractor. Wind tunnel testing is one of the tools that allows us to take this analysis further. It does not replace the normative basis of structural design. It provides additional data that can help tailor the structure more precisely to the conditions of a particular investment. In utility-scale PV projects, decisions made at this early stage can influence structural safety, material use, project costs and the later execution of the solar farm.
The greatest optimisation potential comes before the design is finalised
The greatest opportunity to optimise a mounting structure exists before the structural design is closed. The earlier the engineering team receives information about the site, modules, geotechnical conditions and project assumptions, the greater the opportunity to tailor the system appropriately. For projects where wind interaction is particularly relevant to structural performance, it is also worth assessing whether wind tunnel testing should be included in the design process.
Planning a utility-scale PV project? It is worth discussing the mounting structure before the final structural design begins.
AI tools were used to support the editorial process. The content was reviewed and approved by the ENSON team, which is responsible for the final version and its technical accuracy.