On an industrial hall with a sandwich-panel roof, the quality of a PV installation shows in the details of the mounting structure. The mini rail, the screws and the position of the supports have to work together with the panel and with the roof. At Nectaria Solar we choose quality components and keep the fixings specified in the mounting solution, including additional support for long modules.
Our experience on an industrial hall in Alba County confirms how important these choices are. For you, they mean an installation prepared for the real conditions of the building, and a mounting system in which every fixing point has a purpose.
The mini rail must be chosen for the sandwich roof
In our direct-fixing solutions for sandwich panels, we use mini rails that are compatible with the roof. The short profile allows the supports to be placed where the panels need them, and the configuration has to be matched to the ribs of the roof covering, the thickness of the metal facing and the characteristics of the sandwich panel.
A sandwich panel is an assembly of metal facings and a core, which is in turn connected to the structure of the hall. That is why the capacity of a screw in the sheet metal is only one part of the check. What also matters is how the loads are taken up by the whole panel and transferred to the building.
The official MiniRail documentation requires approval from the sandwich panel manufacturer for this use. Depending on the roof, there are also solutions anchored into the substructure. At Nectaria, the choice starts from the configuration that is compatible with your hall.
Four screws in the Nectaria solution, with specialised fasteners
For the mini rail configurations described here, Nectaria's practice is to fix each piece with four specialised screws. We use the fasteners specified for the support and for the system. The material, thread, geometry and sealing must match the application.
In practice, these fasteners are often called self-drilling screws. The technical name and the installation method are taken from the component documentation: some configurations use thread-forming screws. The MiniRail MK2 specification describes an assembly with four such screws for its application on trapezoidal sheet metal; use on sandwich panels is verified separately.
The price difference looks large per piece: an ordinary self-drilling screw from a hardware store costs around 30 bani (0.30 lei), while one made specifically for sandwich panels costs around 1 leu. Across the whole project, the difference is small compared with the risk of a weak fixing. A generic self-drilling screw bought for another purpose does not automatically offer the same performance. The correct screws come from specialised production and have documented characteristics. The saving made by replacing them with parts that have no technical equivalence affects the very connection between the system and the roof.
The same principle applies to the number of fixings. Reducing to two screws on a mini rail designed for four, just to save money, changes the solution. Nectaria keeps the specified number. There are other systems with supports designed for two screws, but they have their own geometry and documentation.
A quality profile at the right height
Mini rails may look alike, but their geometry, thickness and build quality influence how they behave. We choose the profile together with the fixings and the clamps, aiming for correct support and a stable connection. The quote should describe this part of the work clearly enough.
In our practice, where the configuration allows it, we prefer 70 mm instead of 60 mm mini rails. The greater height provides additional space under the modules, which is useful for air circulation and for organising the installation.
We check the actual distance between the module and the roof against the panel's requirements. For example, the LONGi manual requires a minimum of 10 cm between the frame and the roof for parallel mounting. The height marked on the mini rail should be read together with the geometry of the whole assembly.
In our catalogue you will find the K2 mini rail for trapezoidal sheet metal. The product is selected according to its specification and the accepted configuration.
For long panels, we add a row of support
On sandwich-panel halls, for panels longer than 2 m, Nectaria specifies an additional row of mini rails. Our aim is to support the module better and to limit bending over time under snow. The support and clamping positions must be compatible with the manual for the specific model and with the project loads.
This is our execution choice for these projects. The AIKO installation manual includes different configurations and requires support through clamping appropriate to the loads. The module length is assessed together with the mounting layout; the additional row is placed within the accepted configuration.
In our experience, this choice can increase the cost of the structure by about 33% in the configurations considered. The difference concerns the structure, and for us it is a justified investment in the quality of the module support.
Panel size and roof type are chosen together
The AIKO 650 W, approximately 2.38 m long, is an option we recommend for sandwich-panel halls with the additional support described above, and for ground-mounted systems. The module format is part of the structural calculation from the very beginning.
The LONGi Hi-MO X10 480 W, approximately 1.80 m, and the DMEGC 515 W, approximately 1.98 m, are options we use for all common roof types, with the right solution for each. On flat roofs, Nectaria's rule is to use panels no longer than 2 m.
A pitched sandwich-panel hall and a flat roof have different mounting configurations. We choose the panel and the structure together, so that the large format is properly supported and the roof receives the appropriate solution.
For a PV mounting structure suited to your hall, contact Nectaria Solar on 0723 172 359.
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