When the Adriatic Roars: Lessons from the “Bukovica” Solar Plant Failure for Resilient Project Design

Introduction: A Cautionary Tale from the Croatian Coast

Imagine a state-of-the-art solar power plant, a symbol of renewable energy progress, recently inaugurated amidst optimism. Now picture nearly half of that same facility twisted and torn apart, its valuable photovoltaic (PV) panels scattered like leaves after a storm.¹ This was the unfortunate reality for the “Bukovica” solar power plant near Obrovac, Croatia, in late 2024 or early 2025.¹ As one of Croatia's larger ground-mounted PV installations, boasting a 6.25 MWp capacity and owned by the international energy company Interenergo, its opening in October 2023 marked a significant step in the region's energy transition.³

However, despite the planning and investment poured into this project, it suffered catastrophic damage relatively soon after commissioning. Reports indicate that a severe storm, characterized by the powerful winds notorious in this Adriatic region, overwhelmed the structure.² While one source mentioned snow as a factor, the location's exposure to extreme winds, particularly the infamous Bora, points towards aerodynamic forces as a primary driver of the failure.¹

This incident serves as a stark reminder for the renewable energy industry: successful project development requires more than standard engineering practices and reliance on generic climate data. It demands a deep understanding and rigorous assessment of site-specific meteorological and climatological risks, especially the potential for extreme wind events. This analysis delves into the “Bukovica” case, explores the fundamental science of wind loads on PV structures, examines the unique challenges posed by localized winds like the Bora, and underscores the critical role of expert meteorological due diligence in building resilient renewable energy infrastructure.

The Story of the “Bukovica” Solar Plant: Ambition Meets Harsh Reality

The “Bukovica” solar power plant project represented a significant investment in Croatia's renewable energy landscape. Located in the municipality of Jasenice, near Obrovac, the 6.25 MWp facility was constructed on a degraded area, formerly the site of an alumina factory, transforming it into a potential hub for clean energy.¹ Owned and developed by Interenergo, headquartered in Ljubljana, the plant officially began operations on October 5, 2023, following a construction period of approximately 12 months.³ At the time of its opening, it ranked among the five largest ground-based PV facilities in Croatia.⁴

Notably, this solar plant was not Interenergo's first venture in the immediate vicinity. The company had already established a 10 MW wind farm nearby in 2020.⁴ The development of this wind farm explicitly acknowledged the challenging local conditions, incorporating five turbines equipped with a special storm control system designed to operate in gusts up to 34 m/s (approximately 122 km/h) and blades engineered to withstand extreme winds.⁷ This prior experience and design adaptation for the wind farm highlight an awareness of the significant wind hazards present in the Jasenice area.

Despite this background, the solar plant met a devastating fate just months after its inauguration. A severe storm swept through the region in late 2024 or early 2025, causing unprecedented damage.¹ Reports paint a picture of extensive destruction: estimates suggested almost half the plant was destroyed, with hundreds of 30-kilogram solar panels torn from their mountings and scattered across the landscape, some even landing on the nearby Zaton Obrovački-Maslenica road.¹ The underlying structure was described as twisted, and electricity generation came to a complete halt.² This failure not only represented a significant financial setback for the €5 million joint Slovenian-Austrian investment but also raised serious questions about the resilience of solar infrastructure in the under-Velebit region.²

The location, nestled near the Velebit mountain range, is infamous for the Bora wind, a powerful meteorological phenomenon known for its ferocity along the Adriatic coast.² The fact that a wind farm built by the same developer on adjacent land incorporated specific design features to handle high winds⁷, while the solar plant suffered such extensive wind-related damage shortly after commissioning, naturally prompts scrutiny. It suggests a potential disconnect in applying localized meteorological knowledge consistently across different renewable energy technologies, even within the same micro-location. Was the solar plant designed to withstand the same known local wind extremes acknowledged during the wind farm's development, or were less stringent, perhaps more generalized, standards applied? This question underscores the critical need for tailored, site-specific meteorological assessments for all energy projects.

Understanding the Forces: Wind Versus Photovoltaic Structures

Wind, often perceived simply as moving air, exerts significant physical forces on any object in its path. For structures like solar power plants, understanding these forces is paramount for ensuring structural integrity and operational longevity. The fundamental principle governing wind's impact is rooted in physics: the pressure exerted by wind is proportional to the square of its velocity.⁸ This non-linear relationship means that even a moderate increase in wind speed can lead to a dramatic increase in the forces acting on a structure – doubling the wind speed quadruples the pressure.

A simplified equation captures this relationship:

P = ½ρV²C

where:

• P is the wind pressure
• ρ (rho) is the density of air (approximately 1.225 kg/m³ at sea level, standard conditions)
• V is the wind velocity
• C is an aerodynamic coefficient (incorporating factors like shape, drag, and lift)⁹

This pressure translates into several types of loads on PV arrays:

• Drag Force: This is the force acting parallel to the direction of the wind flow, pushing the structure horizontally.
• Lift Force: Acting perpendicular to the wind flow, lift can be directed upwards or downwards. For tilted solar panels, uplift forces, particularly on the leading edge, can be substantial and are often the critical design load for foundations and anchoring systems.¹¹
• Oscillatory Forces: Wind is rarely perfectly smooth. Turbulence (random fluctuations in speed and direction) and vortex shedding (eddies forming as wind flows around the structure) can induce vibrations and oscillations.¹³ Over time, these dynamic effects can lead to material fatigue and connection failures, even if the structure can withstand static peak loads.

Crucially, structural design cannot rely solely on average wind speeds. Extreme events are dictated by peak gusts, which can be significantly higher than the mean wind speed. Winds like the Bora are particularly known for their extreme gustiness.⁶ While some studies suggest Bora gusts can reach multiples of the mean speed¹⁴, standard engineering codes typically incorporate gust factors based on statistical analysis and terrain characteristics.¹¹

Furthermore, the nature of the wind's turbulence – characterized by Turbulence Intensity (TI) and Turbulence Length Scales (the average size of wind eddies) – plays a vital role.¹⁴ Research specifically on the Bora wind along the Adriatic coast has indicated that its turbulence characteristics, particularly the longitudinal and vertical length scales, can differ considerably from the assumptions embedded in standard wind engineering models like ESDU 85020.¹⁴ This discrepancy is significant. If the actual turbulence structure is more severe or behaves differently than assumed in standard models, applying those standards without site-specific validation could lead to an underestimation of dynamic loads and fatigue stresses, potentially contributing to failures like the one observed at “Bukovica”.

Engineering standards such as ASCE 7 (American Society of Civil Engineers) and Eurocode 1: EN 1991-1-4 (European Standard) provide detailed methodologies for calculating wind loads on structures, including solar panels.¹¹ These codes account for various factors:

• Basic Wind Speed (V or vb): Based on geographical location maps, representing statistically derived wind speeds for specific return periods.
• Exposure/Terrain Category: Reflects the roughness of the surrounding landscape, influencing how wind speed changes with height.
• Topographic Factor (Kzt or co(z)): Accounts for wind speed acceleration over hills, ridges, and escarpments.
• Directionality Factor (Kd or cdir): Considers the reduced probability of the maximum wind speed occurring from the direction most critical to the structure.
• Gust Effect Factor (G or cd): Addresses the dynamic response of the structure to wind gusts.
• Pressure/Force Coefficients (Cpe, Cpi, Cf, CN, cp,net): Aerodynamic coefficients specific to the shape and geometry of the structure (e.g., roof slope, building openness, panel tilt angle) that translate the calculated wind pressure into forces on different surfaces.¹¹

These standards are essential frameworks, but their effective application hinges on accurate input parameters, particularly in environments with unique and severe meteorological conditions. Understanding that Bora gusts near the Bukovica site have been recorded well into the "Hurricane" force category (e.g., 248 km/h or ~69 m/s on Maslenica Bridge⁶) highlights the extreme nature of the forces involved.

The Bora Wind: A Case Study in Localized Meteorological Extremes

The destruction at the “Bukovica” plant cannot be fully understood without appreciating the unique and formidable nature of the Bora wind, a defining meteorological feature of the eastern Adriatic coast. The Bora is classified as a katabatic wind – essentially, cold, dense air from the continental interior accelerating downhill under gravity as it spills over the coastal Dinaric Alps towards the warmer Adriatic Sea.⁶ It typically blows from the northeast quadrant and is characterized by its intense strength, coldness, relative dryness, and, crucially, its pronounced gustiness.⁶ While most common and severe during the winter months, significant Bora events can occur in other seasons as well.⁶ Depending on atmospheric conditions, it can manifest as "bora chiara" (clear bora) under high pressure and clear skies, or "bora scura" (dark bora) associated with cyclonic conditions, clouds, and precipitation.⁶ A distinctive feature during strong Bora events is the creation of "sea smoke" – a spray of fine water droplets whipped up from the sea surface that drastically reduces visibility.⁶

The intensity of the Bora is legendary, particularly in the Velebit region where the “Bukovica” plant is located. This mountain range acts as a significant barrier, enhancing the downward acceleration of cold air.⁶ Documented wind speeds in this area are staggering:

• Speeds near towns like Senj and Karlobag can reach up to 220 km/h (approx. 61 m/s).⁶
• The official record gust measured on the Maslenica Bridge, just north of Zadar and very close to the Jasenice/Obrovac site, is 248 km/h (69 m/s), recorded on December 21, 1998.⁶
• An uncalibrated instrument near the Sveti Rok Tunnel recorded a gust of 304 km/h (approx. 84 m/s) during a Bora event in December 2003.⁶
• Even general descriptions mention mean speeds exceeding 20 m/s (72 km/h) with gusts up to 65 m/s (234 km/h) during severe episodes.¹⁸
• Specific measurements during a December 2004 event recorded gusts exceeding 35 m/s (126 km/h) at Obrovac and the Pag bridge, locations directly affected by Bora flow off the southern Velebit.¹⁹

A critical aspect of the Bora, highly relevant to the “Bukovica” incident, is its extreme spatial variability, heavily influenced by local topography.¹⁸ While fierce winds batter the mountain slopes and certain coastal areas, other nearby locations can experience relative calm. Studies focusing on the "Zadar calm" phenomenon provide compelling evidence.¹⁹ Measurements and simulations show that during severe Bora events where winds on the Velebit slopes reached mean speeds of 30 m/s and gusts of 45 m/s, the Zadar meteorological station recorded significantly lower speeds (mean 12 m/s, gust 27 m/s).¹⁹ Further analysis using SoDAR (Sonic Detection and Ranging) revealed that the strongest Bora flow often occurs aloft (between 300-500m MSL), separating from the surface due to mountain wave effects, leading to weaker winds at ground level specifically in the Zadar area, while potentially maintaining or even accelerating its strength in adjacent zones like Jasenice/Obrovac.¹⁹

This extreme localization demonstrates the potential danger of relying on data from standard meteorological stations, even those relatively nearby, when assessing wind risk in complex terrain. The conditions measured at Zadar are clearly not representative of the conditions experienced just kilometers away at the foot of the Velebit passes near Obrovac. Standard wind maps and models, unless specifically designed with very high resolution and validated for such complex phenomena, may fail to capture these localized jets and the Bora's unique turbulence structure, which deviates from standard engineering assumptions.¹⁴ This necessitates a specialized, hyper-local approach to wind assessment in such regions.

Table 1: Bora Wind Characteristics Summary

(Sources: Synthesized from⁶)

Meteorological Due Diligence: The Cornerstone of Resilient Design

The stark contrast between the ferocious Bora winds documented near the “Bukovica” site and the relative calm sometimes observed at the nearby Zadar station powerfully illustrates a critical point: relying solely on regional climate data or standard wind maps derived from widely spaced meteorological stations can be dangerously inadequate, particularly in areas with complex terrain or known extreme weather phenomena.¹⁹ The failure at Bukovica underscores the necessity of comprehensive, site-specific meteorological due diligence as a foundational element of renewable energy project planning and design.

What does robust meteorological assessment entail? It goes far beyond simply looking up a regional wind speed value. A thorough process typically involves:

1. Detailed Historical Data Analysis: Examining long-term records from nearby stations, but critically analyzing their relevance to the specific site topography. This includes assessing the frequency, intensity, and duration of extreme events like Bora, not just average conditions.
2. High-Resolution Mesoscale and Microscale Modeling: Employing advanced numerical weather prediction models (like WRF - Weather Research and Forecasting) and potentially CFD (Computational Fluid Dynamics) simulations. These tools can model airflow over the specific site topography at high resolution, identifying potential local wind speed accelerations due to terrain features (channeling, ridge effects), flow separation zones, and variations in turbulence characteristics across the project area.
3. On-Site Measurement Campaign (if necessary): In highly complex terrain or where model uncertainty is high, deploying meteorological masts equipped with anemometers and wind vanes, or utilizing remote sensing technologies like SoDAR or LiDAR (Light Detection and Ranging), can provide invaluable ground-truth data.¹⁹ These measurements help validate and calibrate model results.
4. Extreme Wind Analysis (EWA): Applying specialized statistical methods (e.g., Gumbel, GEV distributions) to long-term data (measured or modeled) to estimate the wind speeds associated with specific return periods (e.g., 50-year, 100-year, or as required by relevant design codes). This provides the basis for the design wind speed used in structural calculations.
5. Site-Specific Turbulence Characterization: Analyzing measured or modeled data to determine the Turbulence Intensity (TI) and Turbulence Length Scales specific to the site conditions. Comparing these site-specific values to the assumptions inherent in design codes or standards (like ESDU 85020) is crucial, especially for phenomena like the Bora where standard assumptions may not hold.¹⁴

This detailed meteorological information is not merely background context; it forms critical input for the entire engineering and design process:

• Accurate Structural Load Calculation: Provides engineers with realistic, site-specific values for design wind speed (mean and gust), topographic factors (Kzt), turbulence parameters, and wind profiles to use within the framework of standards like ASCE 7 or Eurocode 1.¹¹ This ensures that the calculated forces accurately reflect the conditions the structure will likely face.
• Informed Risk Category and Design Philosophy: Helps determine the appropriate Risk Category for the project (considering recent trends towards higher categories for solar facilities²¹) and informs the overall design philosophy regarding safety factors and resilience targets. Robust site-specific studies may sometimes support alternative approaches or justify deviations from generalized code provisions, subject to approval by the relevant authorities.²¹
• Optimized Technology Selection: The expected wind loads can influence the selection of PV modules certified for higher mechanical loads (e.g., higher Pascal ratings for wind/snow load) and the choice of mounting structures (fixed-tilt vs. trackers, specific foundation types) designed to withstand those loads.²³
• Reduced Financial and Insurance Risk: Demonstrating thorough meteorological due diligence provides greater confidence to investors and insurers, potentially leading to more favorable financing terms and insurance premiums by quantifying and mitigating a key project risk.

The “Bukovica” failure serves as a costly lesson. The expense associated with comprehensive meteorological assessment upfront is invariably a small fraction of the potential costs of structural failure, which include not only repair and replacement but also lost revenue during downtime, potential contractual penalties, and significant reputational damage. Investing in expert meteorological analysis is, therefore, a high-return investment in project resilience and bankability.

Table 2: Key Meteorological Inputs for PV Wind Load Analysis

(Source: Synthesis based on¹¹)

How Meteo Centar Bridges the Gap

The challenges highlighted by the “Bukovica” solar plant incident underscore the need for specialized expertise that goes beyond standard engineering assumptions. Meteo Centar focuses specifically on providing advanced meteorological and climatological services tailored to the unique demands of each particular client. We bridge the critical gap between generic climate data and the site-specific conditions that truly govern project risk and performance.

Our services directly address the vulnerabilities exposed in cases like “Bukovica”:

• High-Resolution Wind Resource Assessment: Utilizing state-of-the-art modeling techniques to accurately predict wind conditions across your specific project site.
• Extreme Wind Analysis (EWA): Quantifying the risk from extreme events, including localized phenomena like Bora, downbursts, derechos, and cyclonic winds, providing statistically robust design values.
• Site-Specific Climatological Studies: Delivering comprehensive reports detailing all relevant meteorological parameters, including temperature extremes, precipitation, icing, snow loads, and solar resource variability.
• Turbulence Characterization: Analyzing site-specific turbulence intensity and structure to inform fatigue analysis and ensure dynamic stability.
• CFD Modeling for Complex Terrain: Providing detailed airflow simulations to pinpoint areas of wind acceleration, recirculation, and high turbulence within challenging project sites.
• Bankable Meteorological Reports: Producing independent, technically sound reports suitable for project financing, insurance underwriting, and regulatory approval.

Our value lies in delivering the accurate, hyper-local meteorological intelligence necessary to design resilient and reliable renewable energy projects. We specialize in navigating complex meteorological phenomena and challenging terrains, providing the data-driven insights that empower engineers, developers, and investors to mitigate risks effectively and build with confidence, preventing costly failures and ensuring long-term operational success.

Figure 1: Example of one high-resolution numerical Bora simulation in the Velebit area, conducted at Meteo Centar. The colorbar shows the maximum reached speed in m/s

Conclusion: Learning from Loss, Building for Resilience

The significant damage sustained by the “Bukovica” solar power plant serves as a powerful, albeit unfortunate, real-world case study. It vividly demonstrates that in the pursuit of renewable energy development, particularly in environments prone to extreme weather, a thorough understanding and quantification of site-specific meteorological risks are not optional considerations but fundamental prerequisites for success. Relying on generalized data or standard code assumptions without validating them against local conditions, especially potent phenomena like the Bora wind, can lead to catastrophic failures, significant financial losses, and setbacks for the energy transition.

As the renewable energy industry continues to expand, often pushing into more geographically complex regions, and as design standards potentially evolve towards higher resilience requirements²¹, the importance of expert meteorological due diligence will only grow. Investing in specialized services – encompassing detailed historical analysis, high-resolution modeling, extreme event quantification, and turbulence characterization – provides the critical data needed to inform robust engineering design, select appropriate technology, and accurately assess project risk. It is an investment that safeguards assets, ensures operational reliability, and ultimately supports the long-term viability and profitability of renewable energy ventures.

Planning a renewable energy project in complex terrain or a region known for extreme weather? Don't let unforeseen meteorological risks jeopardize your investment. Contact Meteo Centar d.o.o. today for a consultation on a site-specific meteorological risk assessment. [Link to Contact Page]

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