US20120174981A1

US20120174981A1 - Photovoltaic module mounting system

Info

Publication number: US20120174981A1
Application number: US13/392,319
Authority: US
Inventors: Franz Karg; Hans-Werner Kuster; Jaap Van Der Burgt
Original assignee: Saint Gobain Glass France SAS
Current assignee: Saint Gobain Glass France SAS
Priority date: 2009-08-25
Filing date: 2010-08-25
Publication date: 2012-07-12
Also published as: FR2949548A1; WO2011023902A3; KR20120003444U; DE212010000121U1; WO2011023903A3; US20120174968A1; WO2011023903A2; CN202957264U; FR2949494B1; US8887454B2; KR20120004267U; WO2011023902A2; KR200480406Y1; FR2949494A1; FR2949548B1; DE212010000122U1; CN202993633U; KR200480266Y1

Abstract

A system for mounting a photovoltaic module onto a structure at least in part made of metal, in which the photovoltaic module includes at least one photovoltaic cell including electrically conductive elements, the mounting system including, in each region in which the photovoltaic cell is near a grounded metal part of the structure when in the mounted configuration, at least one electrically insulating element positioned between the metal part and the nearest part of the electrically conductive elements of the photovoltaic cell, the total thickness of electrically insulating material between the metal part and the nearest part of the electrically conductive elements of the photovoltaic cell being at least 7 mm.

Description

The present invention relates to a system for mounting a photovoltaic module onto a structure, at least in part made of metal, such as a roof, a facade or a mounting structure of a ground-mounted system.
Within the meaning of the invention, a photovoltaic module is a module capable of converting the energy originating from a radiation, in particular solar radiation, into electrical energy, this definition including hybrid photovoltaic/thermal modules.
Conventionally, a photovoltaic solar module takes the form of a laminated glazing unit comprising photovoltaic cells inserted between a transparent front substrate, designed to be placed on the side of incidence of the solar radiation on the module, and a transparent or opaque rear substrate, designed to be arranged facing a structure for mounting the module.
The front and rear substrates may in particular be formed by sheets of glass or of thermoplastic polymer. In order to allow the mounting of the photovoltaic module onto a structure, such as a roof, a building facade or a mounting structure of a ground-mounted system, the module is conventionally fitted with a metal frame, particularly made of aluminium, which covers its periphery. The attachment of the module to the mounting structure is then achieved by securing the frame to the structure and/or to the frame of another module, if several juxtaposed modules are mounted.
When the mounting structure is made of metal, this conventional mounting system, by means of a metal frame, has the drawback of creating an electrically conductive environment, at a floating or ground potential, around the photovoltaic modules. Thus, at high voltages, in particular at voltages higher than several hundred volts, the modules can be exposed to a high electric field strength, thereby risking damage to the modules. The presence of the metal frame on the periphery of each module and the attachment of the module to the structure at this frame also cause mechanical stresses to occur on the periphery of the module, which harms the mechanical strength of the module. In addition, the metal frame of each module covers active surface portions on the periphery of the module which, if they were not covered, would participate in the energy conversion, which limits the energy conversion efficiency of the module.
It is these drawbacks that the invention is more particularly intended to remedy by proposing a system for reliably mounting photovoltaic modules onto a structure at least in part made of metal, whilst reducing the electric field strength to which the modules are exposed.
To this end, a subject of the invention is a system for mounting a photovoltaic module onto a structure at least in part made of metal, the photovoltaic module consisting of at least one photovoltaic cell that comprises electrically conductive elements, characterized in that it comprises, in each region in which the photovoltaic cell is near a grounded metal part of the structure when in the mounted configuration, at least one electrically insulating element positioned between the metal part and the nearest part of the electrically conductive elements of the photovoltaic cell, the total thickness of electrically insulating material between the metal part and the nearest part of the electrically conductive elements of the photovoltaic cell being at least 7 mm, preferably at least 10 mm, more preferably at least 12 mm.
Thus, the electrically conductive elements of the photovoltaic cell are kept at least 7 mm, preferably at least 10 mm and more preferably at least 12 mm from any metal part at ground potential. Within the meaning of the invention, electrically conductive elements of the photovoltaic cell comprise the electrodes and the busbars of the photovoltaic cell.
According to one embodiment of the invention, said at least one electrically insulating element comprises a rear substrate of the photovoltaic module, said rear substrate being made of an electrically insulating material, particularly of glass or a polymer material.
Conventionally, the photovoltaic module may comprise both a front and a rear substrate, the or each photovoltaic cell being sandwiched between the front substrate and rear substrates.
Preferably, the photovoltaic module is devoid of a metal frame. Thus, the electrically conductive elements of the photovoltaic cell are kept, in the mounted configuration, at at least 7 mm, preferably at least 10 mm and more preferably at least 12 mm from any metal part.
According to an advantageous aspect of the invention, at least one region in which the photovoltaic cell is near a grounded metal part of the structure when in the mounted configuration is an attachment region of the module to the structure, and said at least one electrically insulating element comprises a fastener secured to a rear face of the rear substrate.
According to an advantageous aspect of the invention, the fastener is made of a polymer or a composite material comprising a polymer matrix and electrically insulating fibers.
According to one embodiment of the invention, the fastener is designed to be directly coupled with the metal part of the structure so as to attach the module to the structure.
According to another embodiment of the invention, said at least one electrically insulating element in this attachment region furthermore comprises a portion of a support, said support being secured to the metal part of the structure and the fastener being designed to be coupled with the portion of the support so as to attach the module to the structure.
According to an advantageous aspect of the invention; the support is made entirely of an electrically insulating material, particularly a polymer or a composite material comprising a polymer matrix and electrically insulating fibers.
According to an advantageous aspect of the invention, the fastener comprises a protruding or recessed feature designed to engage with a complementary recessed or protruding feature of the portion of the support, the fastener and the support being designed to be coupled to each other by engagement of their respective features.
According to an advantageous aspect of the invention, the support is secured to the metal part of the structure by snap-fastening.
According to an advantageous aspect of the invention, the mounting system comprises at least two fasteners secured to the rear face of the rear substrate, said fasteners being uniformly distributed over said face and internally offset relative to the peripheral edges of the module.
According to an advantageous aspect of the invention, each region in which the photovoltaic cell is near a grounded metal part of the structure when in the mounted configuration is an attachment region of the module to the structure.
Another subject of the invention is an assembly comprising a structure at least in part made of metal, such as a roof, a facade or a mounting structure of a ground-mounted system, and at least one photovoltaic module mounted onto the structure, in which the module is mounted onto the structure by means of a mounting system as described above. Such an assembly may be a high-voltage power generation system, the voltages of which may reach about several hundred volts relative to ground potential.

The features and advantages of the invention will appear in the following description of several embodiments of a mounting system according to the invention, given solely as an example and made with reference to the appended drawings in which:

FIG. 1 is a perspective view of photovoltaic solar modules mounted onto a structure by means of a mounting system according to a first embodiment of the invention;

FIG. 2 is a perspective view on a larger scale in the direction of the arrow II of FIG. 1;

FIG. 3 is an exploded perspective view on a larger scale of the detail III of FIG. 2;

FIG. 4 is a perspective view in the direction of the arrow IV of FIG. 3 in which the photovoltaic module has been omitted;

FIG. 5 is a perspective view from below of a photovoltaic module of FIG. 1 fitted with fasteners of the mounting system;

FIG. 6 is a side view of photovoltaic solar modules mounted onto a structure by means of a mounting system according to a second embodiment of the invention;

FIG. 7 is a perspective view on a larger scale of a support of the mounting system of FIG. 6;

FIG. 8 is a view similar to FIG. 2, of photovoltaic solar modules mounted onto a structure by means of a mounting system according to a third embodiment of the invention;

FIG. 9 is a cross section in the plane IX of FIG. 8; and

FIG. 10 is a side view of photovoltaic solar modules mounted, by means of a mounting system according to the first embodiment of the invention, onto a structure different from the structures shown in the preceding figures.

In the figures, the thicknesses of the constitutive elements of the photovoltaic modules and of the mounting systems have been exaggerated for the sake of visibility, without conforming to the actual relative dimensions of the elements. In particular, the active layers of the photovoltaic cell of each module have been shown with similar thicknesses to the module substrates, whereas in fact they are thin films of much smaller thickness.
In the first embodiment shown in FIG. 1, photovoltaic solar modules 10 are mounted onto a metal structure 30, of the ground-mounted type, by means of a mounting system 1. The structure 30 is designed to receive the modules 10 at an inclination relative to the horizontal, this inclination being provided to maximize the solar radiation incident on the module. The mean attachment plane in which the modules 10 are attached to the structure 30, denoted n, is inclined at an angle a to the horizontal. As shown in FIG. 1, the angle a of inclination of the plane n to the horizontal is about 45°. More generally, the angle a may lie between 0° and 90°.
In this embodiment, the structure 30 is a stainless steel structure comprising a plurality of beams 31, 33, 35 arranged together to form a triangular framework to which are attached cross-beams 37 having quadrilateral cross sections. The cross-beams 37, a longitudinal axis of which is denoted by X₃₇, are parallel to one another and are intended to receive a plurality of juxtaposed photovoltaic modules 10.
As shown in FIG. 5, each module 10 is a frameless parallelepipedal photovoltaic module that comprises a front substrate or “superstrate” 11, a rear substrate 12 and one or more photovoltaic cells 13 sandwiched between the front substrate 11 and the rear substrate 12. The front substrate 11, intended to be placed on the side of incidence of the solar radiation on the module, is transparent, for example made of an extra-clear transparent glass or a transparent thermoplastic polymer such as polycarbonate, polyurethane, or polymethyl methacrylate. The rear substrate 12, intended to be placed facing the structure 30, is made of any appropriate electrically insulating material, whether transparent or not. The thickness of the rear substrate 12 is denoted by e₁₂.
As a variant, the rear substrate may partially include metal parts, provided that a coating or cover made of an electrically insulating material prevents any electrical connection between these metal parts and ground.
The or each photovoltaic cell 13, positioned between the substrates 11 and 12, is formed by a multilayer stack of thin films comprising, successively, starting from the front substrate 11, a transparent electrically conductive layer 14, in particular based on a transparent conductive oxide, that forms a front electrode of the cell; an absorber layer 15 designed to absorb the energy originating from the incident solar radiation on the cell, in particular an amorphous or microcrystalline silicon-based thin layer or a cadmium telluride-based thin layer; and an electrically conductive layer 16 that forms a rear electrode of the cell. A polymer lamination interlayer, not shown, is used to connect this thin-film multilayer stack to the rear substrate 12 or to a film forming a back cover.
As a variant, the absorber layer 15 of the or each cell 13 may be a thin layer of a chalcopyrite compound containing copper, indium and selenium—called a CIS absorber layer—to which optionally gallium (CIGS absorbing layer), aluminum or sulfur may be added. In this case, the or each thin-film cell 13 comprises a multilayer stack analogous to that described hereinabove, a polymer lamination interlayer, not shown, being also positioned between the front electrode 14 of the cell and the front substrate 11 so as to ensure good cohesion of the module 10 when it is assembled.
In both cases, the lamination interlayer may in particular be made of polyvinyl butyral (PVB) or of ethylene vinyl acetate (EVA).
According to yet another variant, the or each cell 13 may be made from polycrystalline silicon wafers forming a p-n junction.
Each module 10 is equipped with two junction boxes 50 secured to the rear face 12A of the rear substrate 12 intended to face the structure 30, that is the face of the rear substrate 12 on the opposite side to the or each photovoltaic cell 13. The junction boxes 50 are secured to the face 12A by any appropriate means, in particular by bonding, and are positioned symmetrically about a median longitudinal axis X₁₀of the module, in a central portion of the module relative to the direction of the axis X₁₀. The junction boxes 50 are connected together and to the outside by means of cables 52 that allow the module 10 to be electrically connected, once mounted onto the structure 30, with adjacent modules 10 and devices, not shown, for supplying current. Each photovoltaic module 10 is mounted onto the structure 30 by means of four fasteners 20 secured to the module and four supports 40 secured to the cross-beams 37 of the structure. In this embodiment, for each photovoltaic module 10 there are only four regions in which the photovoltaic cell 13 of the module is near the metal structure in the mounted configuration, these regions corresponding to the attachment regions of the module to the structure by means of the fasteners 20 and the supports 40.
Each fastener 20 and each support 40 of the mounting system 1 is made of an electrically insulating material, in particular a polymer or a composite material comprising a polymer matrix and electrically insulating fibers. Examples of appropriate electrically insulating materials include polymers such as polypropylene, polyethylene, polyamide, polycarbonate, which may be reinforced with electrically insulating fibers such a glass fibers or polymer fibers. When the fasteners 20 and the supports 40 of the mounting system 1 are made of a polymer or a material comprising a polymer matrix, each fastener 20 and each support 40 is advantageously made by molding, particularly by injection molding.
The four fasteners 20 are secured to the rear face 12A of the rear substrate 12 by bonding by means of an adhesive. As shown in FIG. 5, the four fasteners 20 are identical to one another and uniformly distributed over the rear face 12A of the module, whilst being internally offset relative to the longitudinal peripheral edges 18 and the transversal peripheral edges 19 of the module. More precisely, if the rear face 12A is divided into four equally-sized quadrants, the fasteners 20 would each be positioned in a central portion of one of the quadrants. Such an arrangement of the fasteners 20 distributed over the rear face 12A reinforces the structure of the module 10 and increases its mechanical strength.
As is clearly shown in FIG. 4, each support 40 comprises a first portion 42 for snap-fastening to the structure 30 and a second portion 44 for coupling to a fastener 20. In this embodiment, the snap-fastening portion 42 has an overall U shape, where the opening of the U is partially closed by a flange 43. One of the lateral legs of the U-shaped snap-fastening portion 42 is formed by the coupling portion 44 whereas the other lateral leg 41 of the U-shaped snap-fastening portion 42 is prolonged by the flange 43 curved toward the coupling portion 44. Thus, the snap-fastening portion 42 has a quadrilateral cross section, open between the flange 43 and the portion 44, that is complementary to the cross section of each cross-beam 37.
Advantageously, each support 40 of the mounting system is made of an elastically deformable material, so that the lateral legs 41 and 44 of the snap-fastening portion 42 are able to be elastically separated from each other. It is thus possible to widen the opening delimited by the flange 43 and the coupling portion 44 so as to snap-fasten the portion 42 to a cross-beam 37 of the structure 30. When the portion 42 is snap-fastened to a cross-beam 37, the cross-beam 37 is received by and held in the interior volume 47 defined by the portion 42 so that the support 40 is secured to the cross-beam 37. In this snap-fastened configuration, it is possible to provide some slack, that is to say a certain gap, between the portion 42 and the cross-beam 37, the support 40 then being able to be slide in the direction of the longitudinal axis X₃₇of the cross-beam.
As shown in FIG. 4, the coupling portion 44, which, in this embodiment, is a lateral leg of the snap-fastening portion 42 of each support 40, comprises a protruding feature 45. This protruding feature 45 is designed to engage with a complementary recessed feature 25 provided in each fastener 20 of the mounting system 1 on a face 20A. The recessed feature 25 of each fastener 20 and the protruding feature 45 of each support 40 have complementary trapezoidal profiles, the cross section S₂₅, S₄₅of each feature 25, 45 decreasing in a longitudinal direction X₂₅, X₄₅of the feature. The features 25 and 45 of a fastener 20 and of a support 40 of the mounting system 1 are thus designed to engage with each other by a sliding movement of one relative to the other in the longitudinal direction X₂₅, X₄₅of the features, as shown by the arrow F₁in FIG. 2. When the feature 25 of a fastener 20 is engaged with the feature 45 of a support 40, the fastener and the support are coupled together.
This coupling of the fastener 20 and the support 40 is reversible in that, when the features 25 and 45 are mutually engaged, there remains a translational degree of freedom of the fastener 20 relative to the support 40 in the direction of the arrow F₂in FIG. 2, i.e. in the opposite direction to the arrow F₁. In other words, when the features 25 and 45 are mutually engaged the fastener 20 and the support 40 are immobilized relative to each other except in the direction of the arrow F₂.
As shown in FIG. 5, each fastener 20 is attached to the rear face 12A of the module 10 so that the axis X₂₅of its recessed feature 25 is parallel to the longitudinal axis X₁₀of the module. The four supports 40 for receiving a module 10 are distributed in pairs on two neighboring cross-beams 37, one of these cross-beams, called the upper cross-beam, being placed above the other, called the lower cross-beam, because of the angle of inclination a of the plane n of attachment of the modules to the structure 30. When each of the supports 40 is snap-fastened to a cross-beam 37, the axis X₄₅of the protruding feature 45 of the support is directed transversely relative to the axis X₃₇of the cross-beam. Thus, when the four fasteners 20 of the module are engaged with four corresponding supports 40, the module 10 is attached to the structure 30 with its longitudinal axis X₁₀directed transversely relative to—the axis X₃₇of the cross-beams 37.
The thickness of each fastener 20 apart from the feature 25 is denoted by e₂₀and the thickness of the coupling portion 44 of each support 40 apart from the feature 45 is denoted by e₄₄. In each attachment region of the module to a cross-beam 37, when the fastener 20 and the support 40 are coupled, the total thickness e₁₂+e₂₀+e₄₄of electrically insulating material positioned between the metal cross-beam 37 and the rear electrode 16, which is the conductive element of the photovoltaic cell 13 nearest to the cross-beam 37, in a direction perpendicular to the plane of the module 10, is at least 7 mm, is preferably at least 10 mm and is more preferably at least 12 mm. In the mounted configuration, the photovoltaic cell of the module 10 is thus electrically insulated relative to the metal structure 30. Advantageously, the thickness e₂₀of each fastener 20 is chosen to equal the thickness e₅₀of each of the two junction boxes 50 of the module. Thus, the module 10 fitted with its two junction boxes 50 and its four fasteners 20 has an optimized compactness that makes packaging, storing and transporting it easier.
A method for mounting photovoltaic modules 10 onto the structure 30, for which the mean attachment plane n of the modules is inclined to the horizontal at an angle a of between 0° and 90°, by means of the mounting system 1 according to the invention, comprises steps such as those described hereinafter.
Firstly, four fasteners 20 are attached to each module 10, in the arrangement shown in FIG. 5, by bonding the face 20B of each fastener, which is on the opposite side to the face 20A, to the rear face 12A of the module.
Supports 40 are also secured to the structure 30 by snap-fastening the portion 42 of each support to cross-beams 37 of the structure. More precisely, for each module 10, four supports 40 are snap-fastened to two neighboring upper and lower cross-beams 37 because of the angle of inclination a of the plane n, namely two supports to the upper cross-beam 37 and two supports to the lower cross-beam 37, by placing the supports onto the cross-beams with an appropriate spacing corresponding to the spacing between the fasteners 20 of the modules 10. Each support 40 is snap-fastened to the corresponding cross-beam 37 such that the cross section S₄₅of its feature 45 decreases toward the ground.
When the snap-fastening portion 42 of each support 40 is mounted loosely or with a certain gap to the corresponding cross-beam 37 in the snap-fastened configuration, that is to say when the support 40 is able to slide relative to the cross-beam 37, it is possible to adjust the position of the supports 40 on the structure 30 before mounting the modules 10 or during mounting. This positioning is then immobilized by bonding the supports 40 to the structure 30 by means of an adhesive which fills the gap between the portion 42 and the cross-beam 37. The positioning of the modules on the structure is easy because the position of the snap-fastened supports on the mounting structure may be adjusted.
Once the modules are fitted with their fasteners 20 and the structure is equipped with supports 40, each module 10 is attached to the structure 30 by engaging the features 25 of the four fasteners 20 of the module with the features 45 of the four supports 40 snap-fastened to the structure 30 for this purpose. This mutual engagement of the features 25 and 45 is obtained by sliding the module 10 downward, in the direction of the arrow F₁in FIG. 2, toward the ground, relative to the structure 30.
Advantageously, the step of securing the fasteners 20 to the rear face 12A of each module is carried out on the production site of the modules 10 and integrated into the production line of the module, whereas the subsequent steps are carried out on the site where the modules 10 are mounted.
When it is necessary to remove or replace a module 10 mounted onto the structure 30, for example in the case of a malfunction of this module, the module 10 is demounted in a particularly simple manner by sliding the module 10 upward, in the direction of the arrow F₂in FIG. 2, relative to the structure 30.
In the second embodiment shown in FIGS. 6 and 7, the elements analogous to those of the first embodiment are denoted by the same numbers increased by 100. The only difference between the mounting system 101 according to this second embodiment and the mounting system of the first embodiment is in the structure of the supports. More precisely, in this second embodiment the snap-fastening portion 142 and the coupling portion 144 of each support 140 are separated from each other and are connected to each other by a joining portion 146. In other words, the coupling portion 144 no longer forms a lateral leg of the snap-fastening portion 142 but is connected to a lateral leg 148 of the portion 142 by the joining portion 146. As shown in FIG. 7, for each support 140, the distance between the rear face of the lateral leg 148 and the front face of the coupling portion 144, apart from the feature 145, is denoted by d.
As above, each fastener 120 and each support 140 of the mounting system 101 are made of an electrically insulating material, in particular of a polymer or a composite material comprising a polymer matrix. In particular, each support 140 is advantageously injection molded in one piece in a composite material comprising a polymer matrix reinforced with electrically insulating fibers. The structure of each support 140 is shown very schematically in FIGS. 6 and 7. In particular, elements for reinforcing the joining portion 146, necessary to ensure that the support 140 has sufficient mechanical strength, are not shown in these figures.
The supports 140 associated with each module 110 are chosen such that the distance d is different for the first pair of supports of the module, snap-fastened to the upper cross-beam 137 of the structure 130, than for the second pair of supports of the module, snap-fastened to the lower cross-beam 137. As shown in FIG. 6 the distance d₁of the first pair of supports 140, snap-fastened to the upper cross-beam 137, is less than the distance d₂of the second pair of supports 140, snap-fastened to the lower cross-beam 137. Hence, when each module is attached to the structure, the module is inclined at an angle p of about 10° relative to the attachment plane n of the modules to the structure. The result is a stepped, shingle-like arrangement of the modules 110 on the structure 130. Such a stepped arrangement of the modules 110 prevents dirt or snow from standing between two adjacent modules and thus limits the dirtying of the modules.
In this embodiment, in each attachment region of the module to a cross-beam 137, when the fastener 120 is coupled to the support 140, the total thickness e₁₁₂+e₁₂₀+d of electrical insulating material positioned between the cross-beam 137 and the rear electrode 116, which is the conductive element of the photovoltaic cell 113 nearest the metal cross-beam 137, in direction perpendicular to the plane of the module 110, is at least 7 mm, preferably at least 10 mm and more preferably at least 12 mm. In this case, the intermediate electrically insulating material comprises both air and the materials that make up the rear substrate 112, the fastener 120 and the support 140.
Advantageously, since a space is provided between the snap-fastening portion and the coupling portion of each support of the mounting system, the circulation of air behind the modules, due to convection, and therefore the cooling of the modules, are improved.
The supports 140 of the mounting system 101 according to this second embodiment may be manufactured in two distinct runs, one having portions 142 and 144 separated by the distance d1 and the other having portions 142 and 144 separated by the distance d₂. As a variant, the supports 140 may be manufactured according to a single template comprising means for modulating the distance between the portions 142 and 144, for example a system of notches. In this case, the joining region between the portions 142 and 144 is provided with specific reinforcement so that the support retains sufficient mechanical strength.
In the third embodiment shown in FIGS. 8 and 9, elements analogous to those of the first embodiment are denoted by the same numbers increased by 200. The mounting system 201 according to this third embodiment is different from the mounting system of the first embodiment in that the fasteners 220 are designed to be directly coupled with the cross-beams 237 of the structure 230. More precisely, each cross-beam 237 comprises a shoulder 238 which, due to the inclination of the plane n of attachment of the modules 210 to the structure 230, is directed upward, away from the ground. To attach a photovoltaic module 210 to the metal structure 230, each of the four fasteners 220 of the module comprises a hook 228 designed to cooperate with the shoulder 238 of the cross-beam 237. The hook 228 of a fastener 220 is able to engage with the shoulder 238 of a cross-beam 237 by a sliding movement of the hook relative to the shoulder in the direction of the arrow F₃in FIG. 9.
When the hook 228 of a fastener 220 is engaged with the shoulder 238 of a cross-beam 237, the fastener is coupled with the cross-beam and this coupling is reversible. The module 210 is attached to the structure 230 when its four fasteners 220 are engaged in pairs with two neighboring cross-beams 237, one of the cross-beams being located above the other. In this embodiment each fastener 220 is made of an electrically insulating material, particularly a polymer or a composite material comprising a polymer matrix and electrically insulating fibers. In each attachment region of the module 210 to a cross-beam 237, the total thickness e₂₁₂+e₂₂₀of electrically insulating material positioned between the metal cross-beam 237 and the rear electrode 216, which is the conductive element of the photovoltaic cell 213 nearest the cross-beam 237, in a direction perpendicular to the plane of the module 210, is at least 7 mm, preferably at least 10 mm and more preferably at least 12 mm. Thus, the conductive elements of the photovoltaic module 210 are electrically insulated relative to the metal structure 230 in each attachment region of the module to the structure, which regions are the only ones in which the photovoltaic cell of the module is near the structure.
As is clearly shown by the embodiments described above, a mounting system according to the invention guarantees that, in each region in which the or each photovoltaic cell of a photovoltaic module is near a grounded metal part of its mounting structure, a certain thickness of electrically insulating material is interposed between the metal part and the nearest part of the conductive elements of the photovoltaic cell, that is to say the rear electrode in the aforementioned examples.
Advantageously, in each region in which the or each photovoltaic cell of the module is near a grounded metal part of its mounting structure, the thickness of electrically insulating material positioned between the metal part of the structure and the nearest part of the conductive elements of the photovoltaic-cell, in a direction perpendicular to the plane of the module, is at least 7 mm, preferably at 10 mm and more preferably at least 12 mm.
By virtue of this arrangement, each conductive element of the module is electrically insulated and maintained at a distance relative to any grounded metal part of the mounting structure, enabling the electrical field strength to which the module is exposed to be reduced.
Thus, a mounting system according to the invention avoids the risk of damage to the modules at high voltages, in particular at voltages greater than several hundred volts, in power generation systems, thereby increasing the lifespan of the modules. An example of a likely damage mechanism at high voltages for thin-film photovoltaic modules is delamination. A mounting system according to the invention may thus enable the use of higher system voltages, above 500 V, and even above 1000 V.
In addition, a mounting system according to the invention enables photovoltaic modules to be quickly and easily mounted onto a structure by engagement of the features of the fasteners directly to the structure or to supports secured to the structure without requiring any special tools. This engagement is effected by simply sliding each module relative to the structure, until immobilization which results from the relative shape of the features. The attachment obtained, of the modules to the structure, is reliable and robust. In particular, the load resistance of the modules is satisfactory by virtue of the uniform distribution of the fasteners over the rear face of each module. Furthermore, assembly of the modules onto the structure obtained according to the invention is reversible, thereby enabling a module to be individually demounted from the structure in the case of a malfunction of this module.
The elements constituting a mounting system according to the invention, namely the fasteners and optionally the supports, have the advantage of being simple and economical to manufacture, in particular by injection molding of a polymer material. Fasteners and supports made of a polymer material are also capable of absorbing, by elastic deformation, vibration movements of the modules relative to their mounting structure, vibrations that are likely to occur for example under the effect of the wind. The result of this is a damping of the noises associated with such vibration movements.
Finally, by virtue of the use of a mounting system according to the invention, it is no longer necessary to have a grounded frame around the periphery of the module in order to attach the module to a structure. Therefore, the entire active surface of the module is exposed to solar radiation, thereby guaranteeing optimum efficiency of the module.
The invention is not limited to the examples described and shown. In particular, in the above examples, the photovoltaic modules are frameless modules. As a variant, the modules may comprise a frame, preferably a non-metallic frame, such that the conductive elements of each photovoltaic cell of the module are maintained at a distance from any grounded metal part in the mounted configuration. As mentioned above, the conductive elements of each photovoltaic cell comprise the front and rear electrodes of the cell, but may also comprise busbars or electrical connections, these not being shown in the figures.
A mounting system according to the invention may also use fasteners and supports having shapes or modes of distribution over the modules and over the receiving structure different to those described above, or even a different number of fasteners and supports. These parameters may particularly be adapted depending on the expected loading on the modules, once they are attached to the structure, for example wind loading or snow loading. As mentioned above, the fasteners are advantageously distributed uniformly over the rear face of the module so that the structure of the module is reinforced. Thus, when each module must withstand a particularly heavy load it is for example possible to provide, in addition to fasteners positioned in each quadrant of the rear face 12A of the module as shown in FIG. 5, a fifth fastener placed centrally relative to the module and to connect the upper and lower cross-beams for receiving the supports with a central beam to which the fifth support may be coupled, directly or via a fifth support snap-fastened to the structure.
When the fasteners of a module are designed to be coupled to supports secured to the mounting structure, as in the first and second embodiments, the supports may be made of a metal instead of an electrically insulating material. In this case, the total thickness e₁₂+e₂₀, e₁₁₂+e₁₂₀of the rear substrate and of the fasteners, both made of an electrically insulating material, is advantageously at least 7 mm, preferably at least 10 mm and more preferably at least 12 mm, so as to guarantee a sufficient distance between, on the one hand, the conductive elements of the or each photovoltaic cell of the modules and, on the other hand, the metal supports, the latter being, due to their electrical conductivity, likely to damage the modules at high voltages if they are too close to the modules.
A stepped, shingle-like arrangement of the modules on the structure, which is an advantageous arrangement in order to limit the dirtying of the modules, may also be obtained by other methods than an adaptation of the structure of the supports of the mounting system according to the invention, as illustrated in the second embodiment, in which a different distance between the snap-fastening and coupling portions is provided from one support to the other. Notably, such a stepped arrangement of the modules may be obtained by modifying the structure of the fasteners or else the receiving structure of the modules, rather than the structure of the supports. The modification of the receiving structure for the purpose of obtaining a stepped arrangement of the modules is illustrated in FIG. 10.
In this figure, the mounting system is that of the first embodiment, but the cross-beams 37, instead of being connected directly to the beams 35 of the structure 30, are connected to rods 39 protruding from the beams 35. More precisely, as shown in FIG. 10, for each module 10 to be attached to the structure 30, the upper cross-beam 37 for receiving the module is connected to protruding rods 39 having a length d₁, while the lower cross-beam 37 for receiving the module is connected to protruding rods 39 having a length d₂greater than d₁. Therefore, in the configuration in which the supports 40 are snap-fastened to the cross-beams 37, themselves attached to the protruding rods 39, and in which the fasteners 20 are coupled to the supports 40, each module is inclined at an angle β of the order of 10° relative to the plane π.
Finally, a mounting system according to the invention may be used for the mounting of photovoltaic modules onto a receiving structure of any type, in particular a mounting structure of a ground-mounted system, a roof or a facade.

Claims

1. A mounting system for mounting a photovoltaic module onto a structure at least in part made of metal, the photovoltaic module comprising at least one photovoltaic cell including electrically conductive elements, the system comprising, in each region in which the photovoltaic cell is near a grounded metal part of the structure in a mounted configuration, at least one electrically insulating element positioned between the metal part and a nearest part of the electrically conductive elements of the photovoltaic cell, a total thickness of electrically insulating material between the metal part and the nearest part of the electrically conductive elements of the photovoltaic cell being at least 7 mm.

2. The mounting system as claimed in claim 1, wherein said at least one electrically insulating element comprises a rear substrate of the photovoltaic module, said rear substrate being made of an electrically insulating material.

3. The mounting system as claimed in claim 2, wherein at least one region in which the photovoltaic cell is near a grounded metal part of the structure in the mounted configuration is an attachment region of the module onto the structure, and the said at least one electrically insulating element comprises a fastener secured to a rear face of the rear substrate.

4. The mounting system as claimed in claim 3, wherein the fastener is made of a polymer or a composite material comprising a polymer matrix and electrically insulating fibers.

5. The mounting system as claimed in claim 3, wherein the fastener is designed to be directly coupled with the metal part of the structure for the attachment of the module to the structure.

6. The mounting system as claimed in claim 3, wherein said at least one electrically insulating element in the attachment region further comprises at least one portion of a support, said support being secured to the metal part of the structure, the fastener being designed to be coupled with the portion of the support for the attachment of the module to the structure.

7. The mounting system as claimed in claim 6, wherein the support is made entirely of an electrically insulating material, particularly a polymer or a composite material comprising a polymer matrix and electrically insulating fibers.

8. The mounting system as claimed in claim 6, wherein the fastener comprises a protruding or recessed feature designed to engage with a complementary recessed or protruding feature of the portion of the support, the fastener and the support being designed to be coupled to each other by engagement of their respective features.

9. The mounting system as claimed in claim 6, wherein the support is secured to the metal part of the structure by snap-fastening.

10. The mounting system as claimed in claim 3, comprising at least two fasteners secured to the rear face of the rear substrate, said fasteners being uniformly distributed over said face and internally offset relative to the peripheral edges of the module.

11. The mounting system as claimed in claim 1, wherein each region in which the photovoltaic cell is near a grounded metal part of the structure in the mounted configuration is an attachment region of the module to the structure.

12. The mounting system as claimed in claim 1, wherein the photovoltaic module is devoid of a metal frame.

13. An assembly comprising a structure at least in part made of metal and at least one photovoltaic module mounted onto the structure, wherein the module is mounted onto the structure using a mounting system according to as claimed in claim 1.

14. The assembly as claimed in claim 13, wherein said assembly is a high voltage power generation system.

15. The mounting system as claimed in claim 1, wherein the total thickness is at least 10 mm.

16. The mounting system as claimed in claim 15, wherein the total thickness is at least 12 mm.