Introduction: Why talk about it now?

The spread of photovoltaic systems on flat roofs in industrial and commercial sectors, the data tells us Gaudí-Terna, is constantly growing.

This acceleration, on the one hand, contributes to the diffusion of technology and encourages new players to enter the market, strengthening the system. On the other, it requires increasing attention to the security and management of the entire life cycle of these solutions, which are also being developed in urban and residential areas.

In this article, we will identify recurring criticality patterns related to the mounting of new photovoltaic systems, which impact performance, roof durability, and insurance/fire safety requirements. The goal will be to summarize three mistakes that should be avoided, but which occasionally occur, in the design and post-installation checks of flat roof systems. This analysis will allow us to propose practical and verifiable solutions, creating a true installation guide. Because efficiency and safety stem from careful mounting design, without simplifications or shortcuts.

Scope of application and prerequisites

In this guide, we focus specifically on flat roofs in industrial and commercial settings, where systems are typically installed with ballasted systems or with point anchors directly to the roof. This is a different context from residential buildings: the height of the buildings, their exposure to wind, the presence or absence of parapets, the shape of the surfaces, and the size of the photovoltaic arrays all create highly variable aerodynamic and load-bearing conditions. Added to this is the nature of the roofing—synthetic membranes in TPO or PVC, bituminous systems, often lightweight prefabricated sheet metal roofing—with compatibility and warranty requirements that directly impact the fixing choices.

Even before discussing brackets and ballast, design requires "reading" the roof as a system: the roofing with its layers (insulation, vapor barrier), slopes and drainage, skylights and smoke and heat exhaust vents (SHEs), access routes, and technical areas. Each of these elements must be evaluated to understand where the loads are concentrated, how the water moves, and which areas remain truly maintainable over time.

Secondly, the operating environment imposes specific technical and supply considerations: in marine or industrial sites, the atmosphere accelerates corrosive phenomena and requires more controlled materials, finishes, and interface details.

Finally, the regulatory and insurance framework is not just a bureaucratic gimmick and must be strictly adhered to for compliance, efficiency, and safety reasons: technical corridors, distances from skylights/EVs, calculation and installation documentation are all conditions that should be considered during the design phase.

In practice, design begins with a few key questions: How much wind hits the building (location, exposure, height, and parapets)? How should the panels be oriented (exposure, slope)? What is the roof structure (membrane, stratigraphy, load-bearing capacity, drainage)? What requirements must be met for maintenance, fire prevention, and supplier warranties? Only after this assessment does it make sense to optimize geometry, ballast, and materials.

Mistake #1 — Underestimating wind action and “simplifying” ballast and layout

The most frequent problems arise from two shortcuts: standardizing the field as if the wind pressures were identical everywhere—when edges and corners are the most critical areas and parapets/discontinuities modify the loads—and relying on generic tables without customizing building height, tilt, distance from edges, and panel dimensions.

The risk is twofold: either an undersized fastening system (with the risk of lifting, micro-displacements, fatigue on the fastenings, wear of the components) or an oversized one (unnecessary weight, puncturing, obstruction of the drainage, presence of permanent loads not compatible with the roofing) ¹.

3 golden rules to avoid risks:

• Avoid placing panels in edge areas: the turbulence created here significantly increases the loads.
• Evaluate the effect of parapets with criteria: It is effective if the parapets are full and continuous, to be effective in shielding the wind; the magnitude depends on theheight of the parapet and the building and is limited to the edge area.
• Perform comprehensive checks: A panel subjected to wind/snow loads, if not properly anchored, can lift, tip, or slide. The failure mechanism depends largely on the inclination, but it's good practice to perform thorough checks.

Risk signals on construction sites: ballast that moves, even slightly, after episodes of wind, signs of chafing on the membranes, loose clamps.

Mistake #2 — Pairing incompatible materials and fasteners in sensitive environments

In aggressive marine or industrial environments, the combination of aluminum and stainless steel without adequate dielectric insulation, or the use of finishes not suitable for the environmental class, could lead to galvanic phenomena and what is known in jargon as "pitting": the former refers to corrosion due to the presence of distinct metal pairs in electrical contact when wet by water, saline solutions and so on – as frequently occurs in systems exposed to the elements; pitting, on the other hand, is a localized corrosion that affects materials with aluminum or stainless steel coating when the covering film is broken, with the risk of fracture of the support.

This is an issue that's sometimes overlooked in the specification stage, partly due to the way materials are selected: sometimes, fasteners are selected for their mechanical strength, not their electrochemical and environmental compatibility. Condensation cycles and hygroscopic deposits further accelerate the attack; over time, rust, loss of torque, and compromised grounding points may appear.

4 golden rules to avoid risks:

• Designing metal-to-metal interfaces: evaluate the installation environment and, if necessary, provide insulating washers between the aluminum and stainless steel screws.
• Specify finishes: always choose components treated to resist aggressive atmospheric agents: stainless steel bolts, hot-dip galvanizing, tempering or anodizing of aluminum.
• Treat drainage and promote drying: design contact points to facilitate water drainage, avoiding stagnation.
• Define an inspection plan: check torques, surfaces, and oxides frequently and cyclically. International best practices suggest at least annual inspections, including a photographic report.

Error #3 — Neglecting coverage and fire safety requirements (access routes, drainage, membranes)

The most frequent critical issues emerge when the final project, with the aim of maximising the kWp produced, sacrifices some complementary aspects of the work²Typical cases include missing or too-narrow corridors for maintenance and rescue operations, drainage partially covered by ballast or wiring, and membranes exposed to puncture from concentrated loads. Distances from skylights, smoke vents (EVs), and penetrations must also always be respected, otherwise the manufacturer's warranties will be immediately affected.³.

4 golden rules to avoid risks:

• Designing the corridors: size emergency lanes, fire lanes, and access routes consistently with insurance standards and practices. It's a good idea to always include them in the plans and specifications.
• Always keep the drains clear: establish “no-go zones” around drainpipes, route wiring along elevated walkways, and provide protection where necessary.
• Ensure compatibility with the roof membrane: the most widely used technology involves the insertion of anti-puncture mats.
• Always consider crossings and distances: take care of cable glands, flaps and seals, maintain minimum distances from skylights/EVs and document with “as built” drawings.

Some operational best practices

A robust project progresses step by step, without leaps. It begins with an on-site inspection and evidence collection: a roof survey with measurements, parapet elevations, actual slopes, membrane condition and brand, and available warranty documents. This phase includes checking drainage and mapping discontinuities (skylights, vents, and EVs), as well as characterizing the site in terms of solar exposure and environmental factors—atmospheric corrosiveness, radiation, temperature fluctuations, and so on.

Wind modeling follows with a zone-by-zone approach—corners, edges, and infield—integrating the building's height and size, exposure, and presence of parapets. It is at this stage that the setbacks are decided and the external rows are sized, often the real difference between a stable structure and one susceptible to wind events. In parallel, the fastening philosophy is defined: aerodynamic configurations and weight distribution, point anchors where permitted and useful, and puncture-resistant layers consistent with the membrane.

The choice of materials is not simply a matter of specifications, but must be tailored to the context. Harsh environments require higher-performance fasteners and finishes, as well as insulated interfaces between dissimilar metals. It's a good idea to establish an inspection plan at this stage, including torque checks and surface condition checks, so that maintenance becomes a routine and not an emergency intervention.

The project concludes with a design of the surfaces to ensure full accessibility for maintenance workers: walkable corridors and entrances, wiring arranged in walkways, and free and accessible drainage.

The testing must include targeted tests (tightness, wetting to check for stagnation, tightening torque checks, photographic surveys) and the submission of documentation that ensures the coverage and system guarantees. In this sequence, every decision is tracked and justified: this ensures efficiency, durability, and compliance from the very first iteration.

Conclusion: the new needs of the sector and the TEKNOMEGA approach

Every roof tells a different story: the geographic location, the building's height, the panel inclination, and the drainage, skylights, and environmental conditions vary. For this reason, a photovoltaic system and its mounting cannot be standard: they must be designed based on the site, with calculations that consider the areas most exposed to wind and the actual geometry of the field, and with material and finish choices consistent with the atmosphere in which the system will operate. Attention to detail—from interfaces that preserve the sheaths to clear waterways, from fire corridors to long-term maintenance—is what makes a system not only compliant, but truly efficient and long-lasting.

In this scenario, TEKNOMEGA acts as a technical partner, not just a supplier: in compliance with Technical Construction Standards, it models wind loads, selects components and treatments based on engineering criteria, and ensures compatibility with panel manufacturers. The process concludes with the provision of complete technical and insurance documentation, ensuring the owner has certainty about performance and liability. The result is a measurable balance: less risk, higher yield, and guarantees maintained throughout the system's life cycle.

¹ CFPA-E Guideline No. 37:2025: https://cfpa-e.eu/app/uploads/2022/05/CFPA_E_Guideline_No_37_2025-F.pdf  
² Fire Department, Fire Prevention Guidelines for the Design, Installation, Operation, and Maintenance of Photovoltaic Systems: https://www.vigilfuoco.it/sites/default/files/2025-09/COORD_NOTA_01_09_2025_n_14030_linee_guida_FV.pdf
³ European recommendations on corridors/fire lanes: https://cfpa-e.eu/app/uploads/2022/05/CFPA_E_Guideline_No_37_2025-F_1.pdf

Sources consulted:

Global FM Data Sheet 1-15 (PV systems on roofs);
CFPA-E Guideline No. 37:2025: https://cfpa-e.eu/app/uploads/2022/05/CFPA_E_Guideline_No_37_2025-F.pdf  
Seminars/slides on ASCE 7-16 Rooftop Wind Design (Maffei Structural Engineering/SEAOC);
Technical notes Aviva Risk Solutions on roof-mounted PV;
Best practices for roof-mounted PV (AXA-XL);
US DOE/FEMP Managing and Mitigating Solar PV Corrosion;
Guidelines CFPA Europe n.37 e FRISSBE/ZAG on BAPV fire safety;
2025 Updates of the Fire fighters for the mantle–fasteners interface.