Profiles for fixing rigid plates

Abstract

The present invention relates to profiles for attaching rigid plates, especially photovoltaic modules, to a roof and to a method and system for attaching photovoltaic modules to a roof structure with the help of profiles.

Description

[0001]The present invention relates to profiles for attaching rigid plates, especially photovoltaic modules, to a roof and to a method and system for attaching rigid plates, especially photovoltaic modules to a roof structure.BACKGROUND OF THE INVENTION[0002]Roofs are an ideal place to install photovoltaic modules. Rigid Si photovoltaic modules are very well known but are difficult to handle (they are heavy) and require expensive heavy frames to install them on the roof.[0003]To make a.o. a commercial (i.e. essentially flat) roof watertight, it is well known to use a polymeric or a bituminous waterproofing membrane as a top layer of the roof (commercial buildings). In the case of a roof having on its top a waterproofing membrane, many penetrations of this membrane will generally be required to install the frames for the rigid Si photovoltaic modules. All these penetrations may lead to leakage and to cold bridges (leading to condensation inside the roof structure). Moreover not all r...

AI Technical Summary

Benefits of technology

[0083]Improved reaction to fire when the modules are attached on a metal sheet and therefore completely separated from the waterproofing membrane by this metallic fire barrier sheet, which further works as a heat sink and therefore greatly limits fire propagation.

[0084]Possibility to achieve outstanding reaction to fire when layers d) contain enough halogenated flame retardant, allowing for the use of a thick protective transparent EVA adhesive layer b)

Problems solved by technology

Rigid Si photovoltaic modules are very well known but are difficult to handle (they are heavy) and require expensive heavy frames to install them on the roof.

All these penetrations may lead to leakage and to cold bridges (leading to condensation inside the roof structure).

Moreover not all roof structures are suited to carry heavy frames, which will catch the wind (sail effect).

On a pitched roof this is also not aesthetical.

With such system, the slope of the modules (tilt angle) is anyway limited due to the wind up-lift resistance and due to shading issue (the modules are close to each other because their substrate or support must be “interlocking”; therefore modules installed with a high tilt angle will cast shadow on the modules behind).

The weight of the pavers may further be incompatible with the load bearing capacity of many commercial buildings.

Gluing operations are however quite delicate on the roof.

The (self-) adhesive may be further not compatible with the existing waterproofing membrane.

Gluing of such photovoltaic modules directly onto the waterproofing membrane will also block or at least much reduce the water vapor permeability of the waterproofing membrane, leading potentially to condensation problems inside the roof structure and / or to damages to the photovoltaic cells and / or to internal delamination of the encapsulating layers of the photovoltaic modules.

The known photovoltaic waterproofing membranes suffer from several drawbacks:Risk of formation of creases during installation because of the differential internal tensions.the modules are very easy to steal.Internal tension as a result of thermal cycli (sun-night) due to the poor matching of the coefficients of dilatation of the modules and of the polymeric films, sheets and glues.The water vapor permeability trough the sheet is partly blocked resulting into:Increased condensation into the insulation panels.Increased risk of delamination of the internal layers of the photovoltaic modules.a higher temperature of the photovoltaic module compared to an installation on a not insulated substrate. and the temperature inside the building will be increased.These membranes are difficult to install as the insulation panels have to be partly cut out (carved) to encompass the connection and cables.Difficulty to access the connections (which are under the welded membranes when installed, meaning that the membrane has to be cut).The choice of the insulation material is limited to such with high reaction to fire.Parts of the waterproofing membrane cannot be covered with photovoltaic modules.They are expensive because they are produced in two steps (production of the PV modules in the first step and lamination in a second step).

This may lead to development of micro-organisms which will attack / damage the waterproofing membrane (especially with plasticized poly vinyl chloride (P-PVC)) and / or the module.

The profiles have to be soft at least at their membrane facing side because otherwise temperature changes and other stresses could lead to damages of the membrane like creases or cracks.

Indeed, it is very difficult to obtain a totally defect free connection (i.e. a watertight connection without some little infiltrations) between the soft profiles and the waterproofing sheet, as a result of dirt and several pollutants which adhere to the existing waterproofing sheet.

The production process is more expensive and needs by-pass diodes to function properly (shadow effect).

It may bring higher lightning risk and electrical break-down risk.

The modules are difficult to steal as the modules can mechanically be fastened with special screws (anti-theft screws)

No development of micro-organisms (plasticizer extraction) thanks to the ventilation of the space between the waterproofing membrane and the modules

Possibility to attach all the modules together with anti-theft screws: theft of modules becomes very difficult.

Possibility to install curved metallic profiles along the edges of the area of the roof covered by modules: limitation of lightning risk and of theft.

Big rigid modules (6 m length of steel) may damage the waterproofing membrane by dilatation-contraction when directly glued with strong adhesives.

Soft (weak) adhesives avoiding that risk are prone to storm damages.

Adhered systems are indeed not always able to transmit to the roof structure the forces applied on the profiles, e.g., when the PV modules get wind from behind.

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