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Can Ballast-Free Vertical Solar Panels Withstand Strong Winds?

Trygve Mongstad
Feb 213 min read

Updated: Mar 10

Wind load plays a crucial role in the design of solar systems mounted on buildings. Typically, conventional solar panels installed on flat roofs need substantial ballast or mechanical fastening to resist wind forces, adding complexity and weight to the setup. Over Easy Solar's VPV unit offers a unique solution, with a design that is specifically optimized to resist wind forces, eliminating the need for ballast or fasteners.

Unlike traditional tilted panels, our VPV unit is designed to eliminate wind uplifts and minimize push forces. Here's how we've achieved this:

  • No Uplift Forces with Vertical Structures Unlike angled panels, vertical solar structures do not generate uplift forces. This means that a VPV solar installation on a flat roof will never be lifted by the wind, ensuring stability even in strong winds.

  • Low-Profile Design for Reduced Wind Loads Our low-profile solar panels (approximately 25 cm in height) are placed closely together, which significantly reduces wind resistance. By shading the wind from one another, the panels help prevent strong wind pressures.

  • Efficient Wind Load Distribution In a VPV installation, all the panels are interconnected, which helps distribute local wind forces evenly across the entire array. This means that larger solar installations are more resistant to wind than smaller ones, improving durability and performance.


Wind load simulations (CFD) of vertical solar panels on a rooftop
Wind load simulations with computational fluid dynamics (Fraunhofer ISE)

We also understand that structural engineers need solid proof before trusting a system with minimal to no fastening. That's why our product, developed by a team of experienced solar experts and researchers, has gone through multiple independent validation processes to ensure its reliability and performance.

Computational Fluid Dynamics (CFD) Simulations

  • We have conducted advanced CFD modeling with Fraunhofer ISE, a leading research institute in solar technology, to simulate wind behavior around the VPV Unit.

  • These simulations account for different roof types, wind directions, and environmental conditions to assess pressure distribution and uplift forces.

Wind Tunnel Testing

  • Physical testing was carried out at IFI Aachen, a leading institute for wind load assessments in Europe.

  • Measurements and analyses are in accordance with the German Standards DIN EN 1991-1-4:2010-12, DIN EN 1991-1-4/NA:2010-12 and the wind tunnel testing guideline of the German/Austrian/Swiss Wind Engineering Association, WtG, as well as EN 1991.1.4:2005 and ASCE 49-21.

  • Wind tunnel tests confirmed that the VPV Unit does not experience significant uplift and is ballast-free in typical urban wind conditions.


Wind tunnel testing of vertical solar panels on rooftop
Wind tunnel testing of vertical solar panels on rooftop

Real-Life Testing & Monitoring on Actual Rooftops

  • We have successfully installed VPV units on various buildings across Europe, including locations in Germany, Norway, and Switzerland, all subjected to different wind conditions. The most wind-exposed installation is located in Tromsø, where the reference wind speed reaches up to 27 m/s.

  • All these installations have been closely monitored for several years, with no recorded incidents of wind-related displacement.

  • The system has proven to remain stable even during storm events, confirming the accuracy of our wind load calculations and showcasing the real-world performance of our VPV technology.


Wind load is a critical factor in the design of any building-mounted solar system. Traditional solar panels on flat roofs often require heavy ballast or mechanical fastening to withstand wind forces, which can add complexity and weight to the installation. The VPV Unit from Over Easy Solar offers a different approach—engineered for low wind forces, it minimizes the need for ballast or fastening in most cases. Vertical Solar Panels Reduces Wind Load and Ballast Need The VPV Unit is designed to eliminate wind uplift compared to traditional tilted panels and keep push forces to the minimum. Here’s how we’ve done it: Vertical structures do not generate any uplift forces. This means that a VPV structure on a flat roof never can be lifted up. Low-profile solar panels (ca 25 cm height) are placed relatively closely together, and they have very low wind loads since the panels are "shading" the wind from each other. Distributing wind loads. In our VPV installations, all the panels in an array are connected together, and local wind forces are distributed over the entire installation. Therefore, a large installation will be more wind-resistant than a small one. Wind load simulations with computational fluid dynamics (Fraunhofer ISE) Simulation, Testing and Real-World Validation of Wind Loads We understand that structural engineers need clear evidence before trusting a system that requires little to no fastening. Our product is developed by a team of experienced solar professionals and researchers, and we’ve subjected the VPV Unit to multiple independent validation steps: Computational Fluid Dynamics (CFD) Simulations We have conducted advanced CFD modeling with Fraunhofer ISE, a leading research institute in solar technology, to simulate wind behavior around the VPV Unit. These simulations account for different roof types, wind directions, and environmental conditions to assess pressure distribution and uplift forces. Wind Tunnel Testing Physical testing was carried out at IFI Aachen, a leading institute for wind load assessments in Europe. Measurements and analyses are in accordance with the German Standards DIN EN 1991-1-4:2010-12, DIN EN 1991-1-4/NA:2010-12 and the wind tunnel testing guideline of the German/Austrian/Swiss Wind Engineering Association, WtG, as well as EN 1991.1.4:2005 and ASCE 49-21. Wind tunnel tests confirmed that the VPV Unit does not experience significant uplift and is ballast-free in typical urban wind conditions. Wind tunnel testing of vertical solar panels on rooftop Real-Life Testing & Monitoring on Actual Rooftops We have installed VPV Units on multiple buildings across Europe, including sites in Germany, Norway, and Switzerland, in a range of wind conditions. The most wind exposed project is located in Tromsø, north of Norway, close to the sea with a reference wind speed of 27 m/s. All of these installations have been monitored over several years, and we have seen no incidents of wind-related displacement. The system remains stable even in storm events, validating our calculations with real-world performance. Vertical solar installation during winter storm in Tromsø, Norway.
Vertical solar installation during winter storm in Tromsø, Norway.

To further guarantee safety and compliance, we also conduct a comprehensive wind load calculation for each installation, taking into account:

Factors that affect Wind Load calculations

  • Local wind zone classifications

  • Building height and size

  • Surrounding terrain and shielding effects

  • Size of the solar installation (number of VPV Units)

For most urban buildings with limited height, our calculations confirm that our VPV unit requires no additional fastening. For taller or more wind-exposed structures, we evaluate whether specific wind mitigation measures are necessary, providing a customized and robust solution for each project.

Since our VPV Unit normally does not require ballast or mechanical fastening to the roof, this offers additional key advantages:

  • Preserves Roof Integrity Many flat roofs, especially green roofs and older buildings, have strict load-bearing limits. Avoiding heavy ballast makes solar installations feasible on a wider range of buildings.

  • Simplified Planning and Installation Without the need for concrete blocks or complex mounting systems, the installation process is streamlined, reducing both labor costs and material expenses. This simplified approach also minimizes the risk of errors during planning and installation, making the entire solar project more efficient and easier to manage.

  • No Roof Penetration Unlike traditional systems that require drilling into the roof - introducing the potential for leaks and long-term maintenance problems - the VPV unit typically does not require penetration, ensuring the building’s waterproofing remains intact.

In conclusion, wind load plays a vital role in solar system design for flat roofs. Over Easy Solar's VPV unit offers a unique solution that eliminates the need for heavy ballast or fasteners, simplifying installation while ensuring stability.

Contact us for technical information and wind assessment for your project as we encourage engineers, architects, and building owners to examine our wind load data and discover how our VPV Unit can be incorporated into your projects.

 
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