Structural Safety in Extreme Weather: Why Solar Installations Require Precise Engineering

As climate change accelerates, extreme weather events are becoming more common across Europe. With solar power plants having a lifecycle of over 30 years, dimensioning wind and snow loads based on general estimates creates a significant structural risk. Long-term reliability is achieved only through site-specific calculations, EN 1090 certified quality, and materials designed for cyclic loading.

According to reports by the European Environment Agency (EEA), weather-related extremes are increasing and intensifying across the continent [1]. For the solar energy industry, this poses a challenge: mounting systems installed today must withstand the weather conditions of the 2030s and 2040s.

Ensuring the longevity of a solar power plant is not guesswork. It is the result of engineering work based on three pillars: precise calculation, material fatigue resistance, and controlled quality.

1. Site-Specific Design and Standards: The Role of RAULI APP

A common mistake in solar projects is treating mounting systems as just bulk hardware rather than critical structural components. However, a safe installation requires that wind and snow loads are accounted for based on local conditions.

RAULI APP was developed to eliminate guesswork from the planning process. The software functions as a structural design tool that ensures the installation is dimensioned to last.

• Calculation and Standards: The software determines loads following European calculation principles. Our roof mounting systems comply with the latest RT 103756 guideline (in finnish), which sets strict requirements for mounting systems specifically in Northern conditions.

2. Material Technology: SSAB Galfan® and Xylan Coating

Wind load is rarely static; it is dynamic and cyclic. A mounting system experiences millions of load cycles during its lifecycle. This highlights a critical difference between materials.

• S-N Curve (Wöhler): Steel has a distinct fatigue limit. If the stress level remains below this limit, the material can theoretically withstand an infinite number of cycles without fracturing [2]. Most aluminum alloys do not possess this property, making them more vulnerable to long-term cyclic stress.

• Superior Corrosion Protection: In our structures, we utilize SSAB’s Galfan®- and GreenCoat®-coated high-strength structural steels [3]. These offer superior corrosion resistance compared to traditional galvanization.

• Fastener Durability: A system is only as strong as its weakest link. Therefore, for fastening parts, we use hardened carbon steel with a Xylan coating as well as A2 grade stainless steel. This guarantees that screws and nuts will not fail even in demanding conditions.

3. Managing Thermal Expansion

Solar installations are exposed to large temperature fluctuations (-30°C...+70°C). Materials expand and contract at different rates.

• Steel vs. Aluminum: The thermal expansion coefficient of aluminum is approximately double that of steel [4].

• Structural Stress: In long mounting rails, high thermal expansion causes shear forces on fasteners. A steel-based mounting system minimizes these forces, as the thermal expansion of steel is close to that of the building frame (concrete/wood).

4. Verified Quality: EN 1090, CE & International Standards

Reliability is not just a promise; it is documented fact. The manufacturing process of RAULI products is supervised according to the strictest construction industry standards.

• EN 1090 & CE Marking: Our production is certified to comply with the EN 1090-1 standard in the demanding execution class EXC2. This entitles our load-bearing steel structures to CE marking. RAULI WALL rails already have a product-specific Declaration of Performance (DoP), and we are expanding CE marking to the entire product family according to our production schedule.

• ISO 9001 & 14001: Our operations are certified according to ISO quality management and environmental standards.

• International Approvals: Our products are designed for European-wide markets. As proof of this, the products have been granted a National Technical Assessment by the construction quality control body ÉMI. Additionally, we are finalizing DiBT approval for the German market as well as an EPD (Environmental Product Declaration), which verifies the product's carbon footprint.
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Summary:

Structural safety in solar energy is not a coincidence; it is a calculation. By combining the precise calculation of RAULI APP, the durability of SSAB’s high-strength steels, and EN 1090 certified production, we offer a solution proven to last the entire lifecycle of the panels.

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References

[1] European Environment Agency (EEA): Europe’s changing climate hazards. Overview of the development of extreme weather events in Europe. Link: https://www.eea.europa.eu/publications/europes-changing-climate-hazards-1

[2] Wikipedia: Fatigue Limit. Definition of material fatigue limit and the S-N curve (steel vs. aluminum). Link: https://en.wikipedia.org/wiki/Fatigue_limit

[3] SSAB: Coated Steel Products. Information on SSAB’s coated steels (e.g., Galfan and GreenCoat) that offer excellent corrosion protection for demanding conditions. Link: https://www.ssab.com/en/brands-and-products/steel-categories/coated-steel

[4] The Engineering ToolBox: Linear Thermal Expansion Coefficients. Comparative data on the thermal expansion of different metals. Link: https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html

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