Eurocode and solar panel fixings: standards and safety

The Eurocode: foundation of photovoltaic structural safety

Installing photovoltaic panels on a roof or on the ground represents a long-term investment that requires a rigorous approach to structural safety. Eurocode is the European standard guaranteeing the reliability of solar panel mounting systems . In Belgium, as in France, compliance with these technical standards is mandatory for all professional photovoltaic installations.

This technical guide details the Eurocode principles applied to photovoltaic fixings , structural calculation methods, and conformity criteria to guarantee the sustainability of your solar installation in both countries.

“Compliance with Eurocode standards is not optional: it guarantees a safe, durable, and insurable photovoltaic installation for at least 25 years.” – Structural Engineering Firm

What is Eurocode and why does it apply to photovoltaics?

Definition and scope

Eurocode refers to a set of European standards (EN) governing the design and calculation of building and civil engineering structures. For photovoltaic installations, three Eurocodes are particularly relevant:

• Eurocode 0 (EN 1990) : Basis of structural design and general principles
• Eurocode 1 (EN 1991) : Actions on structures (wind loads, snow loads, self-weight)
• Eurocode 3 (EN 1993) : Design and calculation of steel structures (aluminum rails, metal supports)

These technical standards define the climatic loads (wind, snow, temperature) and the safety factors to be applied when designing photovoltaic mounting systems .

Regulatory obligations in Belgium and France

In Belgium , compliance with the Eurocode is required for:

• Commercial and industrial installations (>10 kWp)
• Residential facilities subject to planning permission
• Any installation requiring a ten-year warranty
• Projects benefiting from regional grants (Wallonia, Brussels, Flanders)

In France , compliance with the Eurocode is mandatory for:

• All professional installations (>3 kWp with grid connection)
• Buildings subject to building permit or prior declaration
• Installations benefiting from purchase obligations (EDF OA contracts)
• Any installation requiring a ten-year warranty

Failure to comply with these standards may result in refusal of connection by the network operator (Enedis, ORES, RESA) and cancellation of manufacturer's warranties.

Photovoltaic mounting systems: typology and selection criteria

Fixings for pitched roofs

Pitched roofs (tiles, slate, sheet metal, steel decking) represent 75% of residential installations in Belgium and France. Wattuneed offers several solutions adapted to each type of roofing:

Tile fixing

The Wattuneed tile fixing kit includes dual-adjustment hooks to accommodate different tile thicknesses (30-60 mm). Installation maintains the integrity of the waterproofing thanks to a rafter fixing system that requires no drilling into the tiles.

Key technical points:

• Corrosion-resistant A2 stainless steel hooks
• Direct fixing to rafters (8-10 mm diameter screws)
• 40x40 mm aluminum rails, maximum span 1.2 m
• Compliance with Eurocode 1 for wind and snow loads

Fixing to corrugated sheet metal

The sheet metal fixing uses specific hooks to maintain the roof's watertightness. The through-fixings are equipped with EPDM seals guaranteeing a 25-year watertight seal.

Fixing to steel decking

The steel roofing system is particularly suitable for agricultural and industrial buildings. It allows for rapid installation with landscape or portrait orientation depending on production needs.

Fixing to slates

Installation on a slate roof requires careful handling due to the fragility of the material. Special slate hooks distribute the load across several slates to prevent breakage.

Fixings for flat roofs (ballasted systems)

On flat roofs , the Blubase mounting systems offered by Wattuneed use weighted systems without drilling , compliant with Eurocode to resist wind uplift forces.

Advantages of weighted systems:

• No perforation of the waterproofing membrane
• Quick installation without roof work
• Optimized tilt angle (10-30°) for maximum production
• Ballast calculated according to Eurocode 1 to guarantee stability

Floor fixings

Ground-mounted photovoltaic installations require concrete foundations or screw piles conforming to Eurocode 7 (geotechnical). The anchoring depth depends on the soil type and local wind loads.

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Structural calculations according to Eurocode: practical methodology

Step 1: Determination of permanent loads (G)

Permanent loads include the weight of the solar panels, mounting rails, and accessories:

• Panel weight : 18-22 kg/m² (standard 400-550 Wp panels)
• Weight of aluminum rails : 2-4 kg/m²
• Weight of hooks and fixings : 1-2 kg/m²

The total weight of a photovoltaic installation varies between 21 and 28 kg/m², which is a negligible load compared to the structural resistance of a traditional frame (>100 kg/m²).

Step 2: Calculation of climatic loads (Q)

Snow loads (Eurocode 1 - EN 1991-1-3)

Snow loads vary significantly depending on the region and altitude. Here are the reference values for Belgium and France:

Snow loads - BELGIUM

Snow loads - FRANCE

In metropolitan France, the territory is divided into 5 snow zones (A1, A2, B1, B2, C1, C2, D, E) according to the national annex of Eurocode 1:

The snow load is applied with a shape coefficient that depends on the roof pitch:

• Roof 0-30°: coefficient 0.8 (possible accumulation)
• Roof pitch 30-60°: coefficient 0.8 to 0 (progressive sliding)
• Roof pitch >60°: coefficient 0 (no snow accumulates)

Wind loads (Eurocode 1 - EN 1991-1-4)

Wind exerts two types of forces on solar panels:

• Dynamic pressure (front face): pushes the panels towards the roof
• Depression (suction) (rear surface): dangerous lifting effect

Reference wind speeds - BELGIUM

In Belgium, the reference wind speed varies from 26 m/s (coastal Flanders) to 23 m/s (Ardennes). This speed is increased depending on exposure:

Reference wind speeds - FRANCE

In metropolitan France, the territory is divided into 4 wind zones according to Eurocode 1 (NF EN 1991-1-4/NA):

Terrain roughness categories (France and Belgium):

The dynamic wind pressure is calculated using the following formula:

q = 0.5 × ρ × V² × Cr × Ce

Or :

• ρ = density of air (1.25 kg/m³)
• V = reference wind speed (m/s)
• Cr = terrain roughness coefficient
• This = exposure coefficient according to building height

"Roof edge and corner areas are subjected to pressure coefficients 50% higher: particular attention must be paid to reinforcing fixings in these critical areas."

Step 3: Combinations of actions (Eurocode 0 - EN 1990)

Eurocode requires calculating several combinations of actions to verify the structure's resistance in all possible scenarios:

Fundamental combination (ULS - Ultimate Limit State):

1.35 × G + 1.50 × Q₁ + 1.05 × Q₂

Or :

• G = permanent loads (weight of panels + structure)
• Q₁ = dominant variable load (wind or snow)
• Q₂ = variable accompanying load

Concrete example - Installation in Belgium

Project: 6 kWp installation (15 panels) in Walloon Brabant, 35° roof, rural exposure.

• Permanent load: 25 kg/m² × 30 m² = 750 kg
• Snow load: 65 kg/m² × 0.6 (form coefficient) = 39 kg/m²
• Wind load: Pressure 800 Pa + Vacuum -1200 Pa

Critical combination: 1.35 × 750 kg + 1.50 × (1200 Pa × 30 m²) = 55 kN lifting force

Concrete example - Installation in France

Project: 9 kWp installation (20 panels) in the Paris region (wind zone 1, snow zone B2), 30° roof, suburban exposure.

• Permanent load: 24 kg/m² × 40 m² = 960 kg
• Snow load: 55 kg/m² × 0.8 (form coefficient) = 44 kg/m²
• Wind load zone 1: Vref 22 m/s → Pressure 700 Pa + Vacuum -1000 Pa

Critical combination: 1.35 × 960 kg + 1.50 × (1000 Pa × 40 m²) = 61 kN lifting force

These loads must be supported by the anchors in the framework , hence the importance of using suitable screws (Ø8-10 mm, length 120-160 mm) and fixing onto solid rafters.

Dimensioning of fasteners

Aluminum support rails

The aluminum rails form the framework of the fastening system. Their dimensions depend on:

• Span between support points : 0.8 to 1.5 m depending on the section
• Rail section : 40×40 mm (standard) to 50×50 mm (high loads)
• Moment of inertia : >8 cm⁴ for 40×40 mm rail

The calculation of maximum deflection (deformation) complies with Eurocode 3:

f_max = L/200 (L = span in mm)

For a span of 1200 mm, the deflection must not exceed 6 mm under maximum load.

Roof hooks and anchors

The fixing hooks must withstand tensile forces (wind uplift) and compressive forces (snow). The selection criteria are:

• Material : A2 or A4 stainless steel (coastal areas)
• Permissible load : >1.5 kN per hook (tested according to EN 1090)
• Height adjustment : 30-60 mm to adapt to the thickness of the cover
• Fixing to rafters : Wood screws Ø8-10 mm, length 120-160 mm, tightening torque 15-20 Nm

Anti-uplift system

In exposed areas (Atlantic/Mediterranean coast, plateau), reinforced anti-uplift devices are mandatory:

• Doubling of anchors at roof edges and corners
• Use of hooks with increased resistance (>2.5 kN)
• Reduction of the span between rails to 1000 mm

Consult the detailed assembly diagrams.

Eurocode compliance verification: tools and resources

Structural analysis software

Several tools are available to perform Eurocode calculations for photovoltaic mounting systems:

• Valentin Software PV*SOL : Complete sizing with Eurocode module
• AutoCAD Structural Analysis : 3D modeling and finite element calculations
• SkyCiv Structural 3D : Online platform with Eurocode library
• Eurocodes Tools : Automatic determination of wind/snow zones by municipality (France)

Wattuneed provides an online toolbox including load calculators and mounting system sizing tools.

Structural engineering firm

For installations >10 kWp or in high-risk areas (fragile roofs, extreme exposure), the services of a structural engineering firm are recommended or even mandatory. Deliverables include:

• Complete Eurocode calculation note
• Mounting diagrams with technical details
• Certificate of conformity to EN standards
• Structural strength report (if required)

Controls and certifications

The certified fastening systems offered by Wattuneed undergo laboratory testing according to the following standards:

• EN 1090 : CE marking of steel and aluminum structures
• ISO 9001 : Quality Management System
• TÜV certification : Mechanical resistance and durability tests

Common mistakes to avoid during installation

Undersized fasteners

Mistake #1: Using insufficient hooks or rails to reduce costs.

Consequence: Progressive deformation, tearing in case of storm, cancellation of warranties.

Solution: Strictly follow the manufacturer's instructions and Eurocode calculations.

Fixing outside the rafters

Mistake #2: Fixing the hooks directly onto the boards or battens without reaching the rafters.

Consequence: Tearing off from the first gusts of wind (resistance <200 N instead of >1500 N).

Solution: Use a rafter detector and screws of sufficient length (120-160 mm).

No leak test

Error #3: Not checking the seal after drilling the cover (through fixings).

Consequence: Water infiltration, structural deterioration, mold growth.

Solution: Apply polyurethane sealants or use hooks with integrated EPDM seals.

Failure to respect edge zones

Mistake #4: Installing roof edge panels without reinforcing the fixings.

As a result, the edge areas experience 50% greater wind forces (increased pressure coefficients).

Solution: Reduce the span between rails and double the anchorages in critical areas.

Climate zone error

Error #5: Applying snow/wind loads from an incorrect area (confusion of municipality, incorrectly estimated altitude).

Consequence: Dangerous undersizing or unnecessary and costly oversizing.

Solution: Systematically check the exact climate zone via official Eurocode maps or online tools (Eurocodes Tools, Dlubal).

Maintenance and periodic inspections

Frequency of checks

Eurocode recommends annual visual inspections to check:

• Condition of the rails and absence of corrosion
• Tighten the fasteners (tightening torques respected)
• Absence of structural deformation
• Sealing of penetration points

After each extreme weather event (storm >100 km/h, snowfall >30 cm), a thorough check is mandatory.

Lifespan and warranties

Eurocode compliant fastening systems offer a lifespan of >25 years with manufacturer's warranties:

• Material warranty : 10-15 years (corrosion, breakage)
• Functional guarantee : 25 years (maintenance of structural performance)

Wattuneed support assists installers and individuals in monitoring and maintaining installations in Belgium and France.

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Frequently Asked Questions (FAQ)

Is Eurocode mandatory for a residential photovoltaic installation?

In Belgium: Yes, for any professional installation >3 kWp and/or requiring a grid connection. Failure to comply may result in refusal of connection and cancellation of warranties. Small self-installations (<3 kWp) are subject to best practices without the requirement for certified calculations.

In France: Yes, for any installation >3 kWp with grid connection or subject to prior declaration/building permit. Installations benefiting from EDF OA contracts must comply with Eurocode. Plug-and-play solar kits (<800 W) are exempt from structural calculations.

How can I find out my wind and snow zone in France?

Several methods are available: 1) Consult the official maps in the national annexes NF EN 1991-1-3 and NF EN 1991-1-4, 2) Use free online tools (Eurocodes Tools, Dlubal, Lisa.blue) which automatically determine the zone by municipality, 3) Contact your local town hall or a structural engineering firm. Note: the altitude of your project can significantly affect snow loads.

What is the difference between through-bolt and non-through-bolt fasteners?

Through-fasteners : These penetrate the roof covering (screws into rafters), guaranteeing the best mechanical resistance but requiring reinforced waterproofing. Non-through-fasteners : Hooks slid under tiles or weighted systems (flat roofs) maintain waterproofing but limit wind resistance. The choice depends on the type of roof and its exposure to the climate.

How many mounting points are needed for a solar panel?

Standard configuration: 4-6 fixing points per panel (2-3 transverse rails with hooks spaced 0.8-1.2 m apart). In exposed areas (wind zone 3-4 in France, Belgian coast): 6-8 points with a reduced span between rails of 0.8-1.0 m. Edge and corner panels require reinforcement with additional anchors (pressure coefficients increased by 50%).

Can I install solar panels on my roof myself?

Technically, yes for small self-built installations (<3 kWp), but with significant caveats: 1) Dangerous work at height, 2) Mandatory knowledge of structural regulations, 3) Manufacturer warranties are often voided, 4) Home insurance may refuse coverage. Wattuneed recommends using a certified installer (QualiPV in France, electrical certification in Belgium) who guarantees Eurocode compliance and airtightness.

What is the lifespan of a photovoltaic mounting system?

A Eurocode-compliant system made with high-quality materials (anodized aluminum, A2/A4 stainless steel) offers a lifespan of over 25 years with minimal maintenance. The aluminum rails and stainless steel hooks are guaranteed for 10-15 years against corrosion and breakage. Annual inspections and post-storm checks allow for the early detection of any damage.

Are snow loads the same in Belgium and France?

No, each country applies its own national annex to Eurocode 1. Belgium uses a system based on altitude with loads ranging from 0.50 to 1.20 kN/m² (50-120 kg/m²). France uses a system of geographical zones (A1 to E) with loads from 0.45 to 3.50 kN/m² depending on the region and altitude. In practice, flat areas have similar loads (50-65 kg/m²), but mountainous areas in France (Alps, Pyrenees) can have much higher loads.

About Wattuneed
Wattuneed SPRL is the Belgian specialist in photovoltaic and renewable energy solutions. We offer a complete range of Eurocode-certified mounting systems , high-performance solar panels , and hybrid inverters for individuals, installers, and businesses in Belgium and France. Our technical team supports you in sizing, regulatory compliance, and the successful implementation of your solar projects.
📍 Headquarters: Belgium | 🌐 Website: www.wattuneed.com | 📞 Technical support: support.wattuneed.com