Errors in Designing Metal Structures for PV Systems

Why mistakes in solar panel mounting are so costly

For commercial rooftop PV systems, the main part of the investment is not only panels and inverters. Metal structures, fasteners, and mounting rails for solar panels directly affect the service life of the plant, its output, and maintenance costs.

A mistake at the design stage of mounting on a flat or pitched roof in Tashkent often leads to three consequences:

• excess steel consumption and higher project cost;
• roofing problems (leaks, deformations, accelerated wear);
• safety risks for people and equipment in strong winds.

All these problems almost always start with an incorrect scope of work (SoW) and the absence of a detailed calculation of metal structures for the specific site.

Specifics of Tashkent and Uzbekistan: climate, roofs, initial data

When designing PV mounting in the region, it is important to consider:

• High insolation and temperature — heating of the roof and metal structures, thermal deformation.
• Gusty winds — especially on open industrial sites and high-rise buildings.
• Different roof types: from old industrial buildings with soft roofing to modern malls and warehouses with sandwich panels.
• Roof load limits — not all existing buildings are designed for the additional weight of metal structures and solar panels.

Ignoring these factors at the start turns even high-quality panels and inverters into a risky asset.

Mistake No. 1. Inaccurate initial SoW and no calculation for the specific roof

A common scenario: the SoW specifies only the plant capacity and an approximate layout, without details on the roof and load-bearing structures. As a result, the contractor offers a “standard” solution that does not take the real site into account.

What is most often missing in the SoW

• exact roof type (soft, profiled sheet, sandwich panel, concrete);
• spacing and cross-section of trusses/beams that can be used for anchoring;
• permissible additional load on the roof;
• height restrictions for structures (wind zones, visibility, neighboring objects);
• maintenance requirements (walkways, access to equipment, safe zones).

Without this data, it is impossible to correctly calculate metal structures for solar panels.

How it should be

• Calculation based on the SoW tied to a specific building: truss, column, and roof build-up diagrams.
• Preliminary roof survey (if possible with a site visit and photo documentation).
• Clarification of load limits from the building designer or operating organization.

The more accurate the initial SoW, the lower the risk of rework and additional costs for metal structures and installation.

Mistake No. 2. Incorrect layout scheme and tilt angle on a flat roof

On flat roofs, there is a temptation to use the simplest possible solutions: minimal tilt, dense layout, a single scheme for the entire building. This leads to a conflict between output, loads, and operation.

Typical miscalculations on flat roofs

1. Excessive tilt angle without considering wind loads and ballasting.
2. No ballast calculation (for non-penetrating systems) — panels can shift or lift in strong winds.
3. Blocking drains and aeration elements with structures.
4. No walkways for servicing panels, the roof, and engineering systems.

What this leads to

• local leaks due to disrupted drainage;
• accelerated wear of waterproofing under metal structure supports;
• forced dismantling and relocation of PV sections;
• reduced output due to shading and inability to perform proper maintenance.

What to consider in calculations for a flat roof

• support layout considering drains and joints;
• tilt angle and row height considering wind zones and shading;
• type of supports: ballast, point, linear, combined;
• protection of the roofing membrane (pads, load distribution plates, etc.).

Mistake No. 3. Ignoring pitched roof type and connection details to load-bearing elements

On pitched roofs, not only the angle is critical, but also the method of connection to load-bearing elements. Decisions are often made “by analogy” with another site, without understanding the actual roof structure.

What is done incorrectly

• Mounting rails are fixed only to the battens, not to rafters.
• Universal self-tapping screws are used without matching them to the specific material (metal, wood, concrete).
• The type of sheet or sandwich panel profile and its thickness are not considered.
• Fasteners are placed too close to the sheet edge or joints.

Risks for the facility

• leaks and damage to the roof build-up;
• fasteners being pulled out under wind loads;
• sheet deformation, vibration, and noise;
• increased maintenance costs and local roof repairs.

How to approach pitched roofs

• specify in the SoW the roof type (metal, tile, sandwich, standing seam, etc.);
• indicate rafter/beam spacing and available anchoring zones;
• develop connection details considering sealing and durability.

Mistake No. 4. Underestimating wind and snow loads for the region

Even in the relatively mild climate of Uzbekistan, wind loads on rooftop PV systems are significant, especially on high-rise buildings and open industrial sites.

Typical mistakes

• calculation based on average values without considering building height and surrounding development;
• identical design for the roof center and edge zones, where loads are higher;
• no check for wind uplift on the outer rows of panels;
• ignoring local snow drifts (depressions, junctions, parapets).

Consequences

• the need to reinforce structures after installation;
• damage to panels, cable routes, and roofing;
• emergency situations during extreme wind gusts.

A correct calculation of metal structures for solar panels must consider your specific site: height, surroundings, wind zones, roof configuration.

Mistake No. 5. Poor attention to corrosion resistance and material selection

Metal structures and fasteners for solar panels operate outdoors for decades. A mistake in material or coating selection does not show up immediately but leads to serious costs in the future.

Common miscalculations

• saving on coatings for supports and mounting rails (minimal corrosion protection);
• combining dissimilar metals without considering galvanic corrosion;
• no protection of cut edges after laser cutting and bending;
• using unsuitable fasteners (bolts, nuts, washers) in terms of strength class and coating.

Material and technology options

Depending on the task and budget, the following are used:

• carbon steel with various types of anti-corrosion protection;
• hot-dip galvanizing for structures with increased service life requirements;
• stainless steel for specific joints and elements where corrosion resistance is critical;
• powder coating as additional protection and a visual solution.

Material and technology choice directly affects cost and service life. It is important to include this in the SoW and agree on it at the calculation stage.

Mistake No. 6. Designs that ignore installation, maintenance, and safety

Even a structure correctly calculated for loads can turn out to be inconvenient or unsafe in operation.

What is often forgotten

• walkways for installers and maintenance personnel;
• safe zones for working at height (guardrails, anchor points for fall protection);
• access to rooftop engineering systems (ventilation units, hatches, antennas);
• the possibility of partial dismantling for roof repairs without disassembling the entire PV system.

How this backfires

• higher installation costs due to complex and non-standard operations;
• increased maintenance time and plant downtime;
• risks for contractors and the operations team.

When developing metal structures for solar panels, it is important to consider not only calculations but also the actual installation and maintenance process.

Mistake No. 7. No coordination of metal structures with logistics and production lead times

Even a technically sound solution can “get stuck” at the production and delivery stage if the contractor’s real capabilities are not considered.

Typical organizational mistakes

• designing complex joints that are difficult or expensive to manufacture in series;
• no unification of elements (mounting rails, supports, connectors);
• unrealistic deadlines with a large volume of metal structures;
• ignoring logistics of long elements and conditions for lifting them onto the roof.

How to minimize schedule risks

• at the SoW stage, discuss with the contractor the manufacturability of the design: laser cutting, metal bending, welding, powder coating;
• include time buffers for drawing approval and possible revisions;
• agree in advance on packing and delivery schemes to the site, especially in constrained urban conditions.

What affects the cost of metal structures for solar panels

The price of mounting and metal structures for PV systems on flat and pitched roofs is formed from several groups of factors.

Main cost factors

Without a specific SoW, it is impossible to quote an exact price. The correct approach is to first detail the task, then perform a calculation based on the SoW, and only then prepare a commercial offer.

How to build a proper SoW for PV mounting design and fabrication

To avoid the described mistakes and get realistic timelines and costs, it is important to prepare a structured SoW.

What to include in the SoW for calculation

1. General site data

   • city, district, building height;
   • building purpose (warehouse, business center, mall, production, etc.).

2. Roof information

   • roof type (flat/pitched), covering material;
   • presence of parapets, superstructures, engineering systems;
   • diagrams or drawings of load-bearing structures (trusses, beams, columns).

3. PV system parameters

   • planned installed capacity;
   • type and dimensions of solar panels;
   • preferred orientation and tilt angle (if any).

4. Requirements for metal structures

   • desired service life;
   • material priorities (steel, stainless steel, combined solutions);
   • height and additional load restrictions.

5. Organizational aspects

   • planned project start-up dates;
   • delivery format (components, subassemblies, on-site assembly);
   • packing and delivery requirements for the site in Tashkent or the region.

The more complete the SoW, the more accurate the calculation and the lower the risk of price revisions and schedule shifts.

Typical client mistakes when working with a PV mounting contractor

A summary of mistakes that most often lead to budget overruns and missed deadlines:

1. Requesting “do it like on the last project” without considering differences in the roof and building.
2. No clear initial data on load-bearing structures and roof build-up.
3. Choosing a solution based only on price, without assessing material life and installation convenience.
4. Bringing in the metal structure contractor too late, when the PV layout is already rigidly fixed.
5. Ignoring wind and snow loads for the specific site.
6. Unrealistic timelines, when clearly insufficient time is allocated for design, production, and delivery.
7. No coordination of connection details with the building’s operating organization.

By considering these points at the start, you can significantly reduce project risks.

FAQ on designing and ordering metal structures for PV systems

1. Can “standard” mounting be used for all roofs?

No. Standard solutions can be a starting point, but metal structure calculations for solar panels must always be based on a specific SoW and roof characteristics. A universal approach increases the risk of leaks, deformations, and failures in high winds.

2. What is more important when choosing a solution: material or panel layout scheme?

These are interrelated. An incorrect layout and tilt angle may require more massive structures and increase project cost. The optimal approach is to first refine the layout, then select materials and coatings for the required service life and budget.

3. Why do different contractors quote very different prices for mounting?

Most often they differ in:

• assumed loads and safety factors;
• selected materials and coatings;
• level of calculation detail based on the SoW;
• approach to installation and maintenance.

Proposals can only be compared correctly when initial data and specifications are aligned.

4. Is it possible to save money by reducing steel thickness or the number of supports?

Formally yes, but this increases risks in terms of load-bearing capacity and durability. Any “lightweighting” must be backed by calculations. Saving on steel without calculations often leads to higher costs during installation and operation.

5. How should timelines be considered when ordering metal structures for PV systems?

You need to separate:

• time for collecting initial data and preparing the SoW;
• time for engineering calculations and drawing development;
• production time (laser cutting, bending, welding, powder coating);
• logistics and lifting to the roof.

The earlier the contractor is involved in the project, the easier it is to stay on schedule.

6. What roof data is mandatory for calculation?

At a minimum:

• roof type and material;
• layout of load-bearing structures and truss/beam spacing;
• presence of parapets, superstructures, zones with load restrictions;
• photo documentation of key joints and general roof views.

Without this, the calculation will be approximate, and the final cost and timelines will be uncertain.

7. Can existing metal structures on the roof be used to mount panels?

Sometimes yes, but only after checking their condition and recalculating loads. Attaching to existing structures without analysis can lead to overloading and roof damage.

CTA: when it makes sense to move to a calculation for your site

If you are planning a PV system on a flat or pitched roof in Tashkent or the region and want to avoid the above mistakes, the next step is to prepare a SoW and submit it for calculation.

You should submit a request for calculation of metal structures and mounting for solar panels once you have at least a basic understanding of the site.

For a prompt calculation based on the SoW, prepare:

• city and site address;
• building and roof type (flat/pitched, covering material);
• approximate PV capacity and panel type (if selected);
• diagrams or drawings of roof load-bearing structures (if available);
• roof photos from different angles, junction details, parapets;
• desired project timeline and phasing (pilot/full deployment);
• material and coating preferences (if any).

Based on this data, an engineering calculation can be performed, material and technology options proposed, production timelines estimated, and a justified cost for a solution tailored to your site can be prepared.