Patent Application
20110174353
The invention relates to a mounting system by which photovoltaic modules are mountable on a supporting structure by means of holders without using any tools. The holders are adhesively affixed to the PV moduls back side. Such mounting systems are particularly required for large-scale photovoltaic on-roof installations and open area installations comprising frameless thin-film modules.
From DE 101 05 718 A1 a photovoltaic module group is known whose PV modules can be suspended into a supporting structure. Therefore, agraffes known from the facade mounting sector are provided on the back side of the PV modules forming a hook connection together with bolts on the supporting structure. From U.S. Pat. No. 5,480,494 A, PV modules are known comprising base bodies formed from metal sheet, that can be mounted to supporting structures by using various hook connections.
From DE 103 29 184 A1, a system for mounting roof construction elements is known. The system comprises several adhesion connectors the corresponding joining elements are suppose to act according to the hook-and-loop principle. The joining elements can be arranged on the back side of the PV module in a self-adhesive manner.
From DE 10 2004 055 187 A1, profile rails for photovoltaic modules are known that can be adhesively affixed onto the back side of a frameless PV module by using a silicone adhesive and that can be screwed with a supporting structure.
From U.S. Pat. No. 5,143,556 A, an elevation for a PV module field is known, the modules of which can be mounted on supporting rails by using holders that are adhesivly affixed onto the modules' back side. Each holder shall encompass the bead at a bolt's head in a clip-like manner, wherein the bolts are singly sticking out from the supporting rails.
With increasingly larger module formats, those mounting systems known do not any longer fulfill the manufacture and installation requirements of industrial photovoltaic plants. Furthermore, some of the known systems are not designed for high wind and snow loads.
Thus, one object of the invention is to develop a mounting system for PV modules by which particularly large-surface frameless thin-film modules are hold carefully and safely with consideration to high wind and snow loads. Additionally, the mounting system shall be installable without using any tools and easier to be manufactured.
The solution of the object is achieved by means of the features given in claim 1. According to claim 1, the mounting system comprises preferably two or even more profile-shaped cross rails that are arranged in parallel to and at a distance to each other and which are provided for holding several PV modules. The cross rails that are preferably identical in construction can particularly be made of an aluminum material by using an extrusion method such as extrusion molding. It is also conceivable to produce the cross rails in a profile-shape by using other materials such as, e. g., wood or steel, and by using other methods.
The cross rails mainly provide a retaining function for the holders and can thus be supported by additional supporting structure for supporting several PV modules in a kind of sandwich construction. However, it is preferably possible that the cross rails at the same time provide the function of a load bearing girder for several PV modules. It is essential for the retaining function of the cross rails that they run in a cross direction within a substructure. In the field of photovoltaic systems this means that the cross rails are aligned in a cross direction to the PV moduls' edges running downwards and/or to the slope line of the PV modules, i. e. to the direction of downhill force. In slant arrangement, the cross rails are thus recognized easily in that they are—preferably horizontally—arranged in different heights.
Additionally, each of the cross rails comprises a plane supporting surface that can also be composed of several parts. The supporting surfaces of the cross rails can thereby build a common inclined plane that is preferably parallel to the module plane. The joining direction then preferably runs downwards and in parallel to the said plane. However, it is also conceivable to provide the supporting surfaces stepwise one below the other. In the case of a common inclined plane, the said plain can be inclined as regards a horizontal plane, particularly in a solar-energetically suitable angle ranging from 20 to 50 degrees.
The mounting system further comprises several holders which are preferably identical in construction and which are each fixed or fixable to the back side of PV module by using an adhesive agent. The adhesive agent may particularly be a silicone-based adhesive which has proven to be reliable in the field of construction engineering for the material combination of metal and glass even under extreme weather conditions. Two-component silicone adhesives are thereby preferred. It is also possible to use, for example, epoxy resin, polyester resin, poly urethane or acrylate adhesives. Furthermore, the adhesive agent can also be provided as a support layer covered with adhesive on both sides. Such a support layer may particularly be embodied as a double sided adhesive pad preferably corresponding to the holder's dimensions. The support layer may have been applied prior to connecting the holder with the module's back side, i. e. in a pre-manufactured manner, onto the holder or, alternatively, onto the PV module, and provided with a removable protective film in a appropriate manner.
By means of the holders, the PV module can be mounted to the cross rails for which purpose each cross rail has at least one holder associated or allocated therewith and each holder has a recess and each cross rail has an integrated protrusion. Alternatively, it is also possible that each holder has such a protrusion and each cross rail has an integrated recess. For mounting, the PV module is then firstly placed onto the cross rails such that the holders lay flat on the supporting surfaces of the cross rails. Herefor, the holders each preferably comprise a plane contact surface at which the holders can be placed onto the supporting surface of the respective cross rail under plane contact and are correspondingly guided in a shiftable manner thereon. Secondly, while laying thereon, the PV module is shifted in a joining direction perpendicular to the cross rails, wherein the recesses and the protrusions are more and more engaging with each other during shifting. Moreover, the joining direction is parallel to the supporting surfaces and is preferably running inclined downwards in the direction of the slope line and/or parallel to an outer edge of the PV module running downwards.
The recess of a holder can particularly be embodied as an indentation of a hook. Such a hook is preferably sticking out from the contact surface of the holder. The protrusion of the respective cross rail operating as a counterpart may advantageously be embodied as an overhang of an undercut groove that is integrated within the cross rail's profile and into which the hook is inserted during the placing. The opening slot of such an undercut groove can separate the supporting surface of the cross rail in preferably two partial areas having approximately the same width.
Alternatively, it is also possible that the recess is provided as an undercut of a hook integrated within the respective cross rail and that the protrusion is provided as an overhang of an undercut groove within the respective holder. Here, the hook can stick out from the supporting surface of the cross rail and the undercut groove can separate the contact surface of the holder.
Moreover, the mounting system according to the invention comprises a retaining safety device. The retaining safety device is provided between at least one cross rail and a holder associated therewith and counteracts a possible backshift of the holder against the joining direction, in particular in the case of wind suction. Such a retaining safety device may, for example, be designed as an snap-fit, or snap-in, connection comprising several joining positions and/or as a blocking device.
The invention comprises several advantages. Thus, the mounting system according to the invention is particularly suitable with regard to manufacture and mounting. The holders can be fixed or attached, preferably in a factory-provided manner, to the back side of the PV module by using an automated and controlled process by means of adhesive bonding. However, alternatively, it is also conceivable to mount the holders thereto on-site. In case the adhesive agent such as a silicone adhesive has elastic properties, moreover stresses resulting from temperature and mounting can be absorbed and the PV module can be supported in a cushioned manner.
As the protrusion or the recess, respectively, has already been integrated within the profile-shaped cross rail, the manufacture of the cross rails is particularly easy. Thus, the latter may preferably be manufactured by extrusion molding or roll forming. Furthermore it is possible in an easy way to design the cross rails with a very high bearing capacity so that the cross rails may support several PV module over a wide span width.
Because of the protrusions or the recesses, respectively, being integrated in the cross rails or rather extending continuously therein, it is possible upon installation to mount the PV module at any arbitrary position along the cross rails. Moreover, the installation is carried out without using any tools and in a particular ergonomic way. So the joining process is divided in a free placing onto the plane supporting surfaces of the cross rails and a subsequent smoothly shifting in a downward direction. After placing and if necessary, the PV modules may further be shifted into another mounting position in parallel to the cross rails. Dividing the joining process in the aforementioned manner is particularly advantageous for large-surface and thus accordingly heavy PV modules.
The plane supporting surfaces offer great advantages as regards statics. So every holder is resting on the associated cross rail with a comparatively large contact area whereby a correspondingly stable and easily calculable load transmission will be possible. This particularly applies for high snow and wind loads. The mounting system is thus particularly suitable for frameless thin-film modules with a surface area of significantly more than one square meter.
A further essential advantage is that tolerances of the distance of the cross rails and the holders resulting from manufacture and mounting can be compensated. In case the cross rails are, for example, spaced apart from each other too broad or too narrow, this can be compensated by means of a various deep engagement of recess and protrusion. Thereby, it is of particular advantage that, independently from the depth of engagement, the holders always rest on the plane supporting surfaces having plane contact and can be shifted thereon depending on the actual distance situation.
Furthermore, the retain safety device prevents that the recess and the protrusion being released from their engagement in the direction against the joining direction, particularly under extreme wind conditions. The said retaining safety device may alternatively or additionally also be designed as an anti-theft device.
Moreover, not only the cross rails but also the holders may be mass-produced in a simple manner by using an extrusion molding process. So it is preferred when the holders are substantially embodied in form of an extrusion molded part or rather being cut off from an extrusion molded profile correspondingly. As for the cross rails, the recess respectively the protrusion can be integrated by extrusion as well.
In summary, with respect to increasingly large-scale and more cost efficient PV modules, the mounting system according to the invention makes a significant contribution to supporting structures for industrial photovoltaic systems that are easier to manufacture and easier to mount.
In a preferred embodiment, the holders are arranged at positions within the inner or interior surface area of the PV module's back side at a distance from the outer contour of the PV module. Thereby, it is appropriate to arrange the holders in such a way that the PV module undergoes a deflection as low as possible in its position of use. In this way, the module may be particularly preserved and its bearing properties for snow loads may be increased. If there are exactly four holders provided for the PV module, the holders or rather their centers may be arranged inwardly at a distance to the outer edges of the PV module by preferably 17% to 27% of the distance towards the respective opposite outer edge. According to a rule of Bessel, a distance to the center of the holders of about 22% is particularly advantageous.
For arranging the holders onto the back side of the PV module, a mounting template can be provided determining the positions for arranging the holders relative to the outer contour of the PV module. By using such a mounting template, the holders can also still be adhesively affixed to the PV modules at the construction site of the photovoltaic system, preferably by using the aforementioned double sided adhesive pads. When using double sided adhesive layers, it is further possible to affix the latter in a factory-provided manner exactly at the desired positions onto the back side surface of the PV modules. In this way, the holders can be positioned on the adhesive layers at the construction site after drawing off a corresponding protective film, whereby the use of a mounting template can be avoided. Thereby, the adhesive film mark those positions for arranging. It is advantageous for an easy mounting and exact positioning process if the adhesive layer respectively corresponds with the outer outline of the holders' adhesion surface being provided therefore.
In a further preferred embodiment, the holders each comprise a plane supporting body or structure having a contact surface and an adhesion surface being parallel thereto. The contact surface and the adhesion surface, or surface for adhesion, are preferably plane. The supporting body or rather the adhesion surface thereof may additionally have a rectangular format, whereby the longer side thereof is preferably aligned in parallel to a longer side of an optionally rectangular PV module. It is of course also possible to provide the supporting body with other forms, particularly also with square or circular adhesion surfaces. In each case, the adhesion surfaces of the holders respectively the supporting bodies that have to be provided with an adhesive agent are sufficiently large in order to retain the PV module safely and to support it gently. In a particular advantageous development, the plane supporting bodies narrows towards the outer edges of its adhesion surfaces. This means that the material thickness behind the adhesion surface diminishes from the center or from a central area of the holder or rather its supporting body to its outside, preferably in a continuous manner. Due to this diminution, the rigidity of the holder, i.e. its supporting body reduces towards its outside, thus preventing a sudden rigidity alteration between the supported and the unsupported areas of the PV module. Rigidity steps and local stress peaks resulting therefrom may thus be avoided effectively, thus preserving the PV module particularly with respect to high snow loads and dynamic wind loads. Additionally, in this way, thrust and shear forces acting on the adhesion may be reduced. A supporting body designed in the said way can particularly have a trapezoid-like and thus extrudable cross section or can be shaped like truncated pyramid having four or more edges or can be shaped similar to a truncated cone. Other shapes for the supporting bodies are conceivable in which the material thickness reduction towards the outside is not linear but, for example, parabola- or hyperbola-shaped. This can be of particular advantage for rotationally symmetrical shapes.
In a preferred embodiment, the recesses and the protrusions appropriately engage with each other in a form-fitting manner when shifting in the joining direction. Thereby, preferably a sliding clearance is provided such that the recesses and the protrusions inter-engage under sliding fit. Therefore, the protrusions and the recesses are preferably designed rigid. In this way, a particular stable and easily calculable connection between the holders and the cross rails is generated comparable to a groove-tongue-connection having a sliding fit. Thus, a lifting of the holders off the supporting surfaces is not possible even under extreme wind suction conditions.
Moreover, it is possible that the recess and/or the protrusions are at the same time limited by the supporting surface of the cross rail or of the contact surface of the holder, respectively. Furthermore, it can be advantageous if a sliding fit is provided between the contact surface as well as an opposite parallel flank thereto at the protrusion or the recess of the holder, on the one hand, and the supporting surface as well as an opposite parallel flank thereto at the protrusion or the recess of the cross rail, on the other hand. Hereby, the flanks can be directly or diagonally opposite to the supporting surface respectively to the contact surface. It is essential for the sliding fit that the respective flank appropriately counteracts to the supporting surface or contact surface, respectively.
Alternatively or additionally, it is possible that the recesses and the protrusions engage with each other in a force-transmitting and form-fitting manner. Therefor, at least one flank of the recesses and/or at least one flank of the protrusions may be designed elastically, for example, in form of an integrated bendable bar, or may abut against elastic elements, in particular against a metal spring. Such a spring can be arranged between the flank of a protrusion and the flank of a recess. It is also conceivable to design the protrusion completely in form of a bendable bar. In each case it is advantageous for compensating distance tolerances if the maximum possible engagement between the recesses and the protrusions is dimensioned appropriately, in particular at least 4 mm. While engaging there exists preferably always a sliding fit.
In a further preferred embodiment, for retaining safety in an arresting manner, a snap-fit, or snap-in, connection comprising several successive joining positions is provided between at least one cross rail and a holder associated therewith. During the shifting process, the joining positions here follow successively in the aforementioned joining direction, preferably in equal distances. In this way, the cross rails and the holders can be connected to each other free from play despite any distance deviation resulting from manufacture or mounting. Thereby, it is possible to design the snap-fit connection that the latter operates against the joining direction in a locking manner, whereby disassembling is not possible any more without further efforts.
The snap-fit connection can particularly comprise a row of teeth integrated within the cross rail and a snap-fit hook elastically arranged at the respective holder, wherein the snap-fit hook is interacting with the row of teeth. Alternatively, it is conceivable to provide the snap-fit connection in the way that an elevation is integrated within the cross rail, for example, in form of a hooked nose, and an elastically arranged row of teeth is provided at the holder, the row of teeth interacting with the elevation. Hereby, it is also possible to provide several successive elevations, preferably in form of a second fixed row of teeth interacting with the elastic row of teeth.
In a particular development, it is furthermore possible to arrange the elements of the snap-fit connection, such as in particular a snap-fit hook and a row of teeth, at the flanks of the protrusions and/or of the recesses. Moreover, it is possible to arrange the elements of the snap-fit connection such that the elements limit the respective protrusions and/or recesses. Hereby, it can be of particular advantage if one of the elastic elements of the snap-fit connection presses the holder against the supporting surface of the cross rail.
In a further preferred embodiment, for retaining safety in an blocking manner, a blocking element is disposed at at least one holder, wherein the blocking element, in a release position, allows a shifting of the holder in joining direction over the supporting surface of the cross rail associated therewith and, in a blocking position, blocks a shifting against the joining direction. In particular, the blocking element can be a latch arranged at the holder interacting with a limit stop at the cross rail. Thereby, it can be of advantage if, in the release position, the latch is turned in a recess provided within the contact surface of the holder and turned out while shifting in the joining direction and abuts against the limit stop of the cross rail in the blocking position.
In a particular preferred embodiment of the mounting system, for each PV module, four point-like acting holders and exactly two cross rails are provided, wherein two holders are associated with one of the two cross rails respectively. Alternatively, it is possible that each of two cross rails is associated by only one line-like acting holder such that the PV module is supported only by two holders. Depending on the module size, it is furthermore possible to provide more than two cross rails and also more than two holders per cross rail and PV module. Thus, it is particularly advantageous for large-surface PV modules to provide two or three cross rails and each three holders. For module formats having an area of several square meters, more holders and cross rails are possible accordingly.
In the following, several exemplary embodiments of the invention will be explained in detail with respect to drawings, wherein:
At first,
The supporting structure additionally comprises four cross rails 2 that are identical in construction. The cross rails 2 are arranged on the two inclined girders 3 and run in a cross direction thereto. The four cross rails 2 are spaced parallel to each other, wherein two adjacent cross rails 2 each hold and support three of the PV modules 1 in a row. Thus, two module rows are provided with three PV modules 1 each. Furthermore, the cross rails 2 are profile-shaped, i. e. they have a uniform cross section all over their length as can be seen in detail in
It is also possible to mount the cross rails 2 onto a pitched roof. It is essential for the function of the mounting system still to be explained that the cross rails 2 as shown run in a cross direction to the inclined girders 3. Correspondingly on a pitched roof, the cross rails would be aligned in a cross direction to the slope line of the pitched roof. In a slanted arrangement, cross rails can also be recognized in that the latter run in different heights horizontally or approximately horizontally. In case of a terrain that is considerably slanting in an east west direction, the cross rails can also significantly deviate from the horizontal. In each case, the arrow 7 is preferably aligned with the direction of the downwards running edges of the PV modules 1, independently from the slope line.
Furthermore,
Alternatively, it is possible to connect the holders 5 provisionally by using a mounting template 8 according to
The holder 5 is fixed to the plane back side 11 of the PV module 1 at its adhesion surface 14 by using an adhesive agent. The adhesive agent can schematically be seen as a flat adhesive layer 12 between the back side 11 of the PV module 1 and the adhesion surface 14. As the holder 5 can particularly be made of a metal material, preferably of an aluminum, and the back side 11 of the PV module 1, designed in form of a frameless thin-film module, can usually be made of glass, a two-component silicone adhesive that has been proven for the said material combination in construction engineering and for outdoor environment can be used for adhesive fixing. Furthermore, such an adhesive can have a cushioning and stress-compensating effect.
Furthermore, it can be seen that the supporting body 13 comprises a trapezoid-like cross section, wherein the contact surface 15 is smaller than the adhesion surface 14 and is arranged approximately in the center and beyond the adhesion surface 14. The material thickness of the supporting body 13 thus reduces continuously beginning from the left and the right edge of the contact surface 15a, b towards the left and the right edge of the adhesion surface 14 by means of two slants 17. By this diminution, also the rigidity of the holder 5 reduces towards the outside, whereby a sudden rigidity alteration between the supported and the unsupported area of the PV module 1 is avoided. Alterations in rigidity and local stress peaks resulting therefrom can thus effectively be avoided, preserving the PV module 1 particularly against high wind and snow loads.
Additionally, the cross rail 2 associated with the holder 5 is shown in
In the upper area of the cross rail 2, two bars 18a, b projecting at the left and at the right side, the bars 18a, b each providing a partial surface of a common plane supporting surface 19a, b towards the top. The supporting surface 19a, b is interrupted approximately in the center by the opening slot of an undercut longitudinal groove 20. The side walls 21a and 21b of the said undercut longitudinal groove 20 connect the projecting bars 18a, b with the lower area of the cross rail 2. There, the cross rail 2 comprises a trapezoid-like hollow section having a slant bar 22 both at the left side and at the right side as well as having a bottom chord 23 and a top chord 24. The bottom chord 23 and the top chord 24 are arranged in parallel to each other, wherein the bottom chord 23 is broader than the top chord 24. By means of the bottom chord 23, the cross rail 2 rests on the inclined girder 3 according to
Furthermore, in
As particularly can be seen in detail from
Moreover,
Furthermore, a blocking element embodied as a latch 35 can be seen in
According to
A second joining motion 41 finalizes the joining process and is carried out by means of shifting the holder 5 perpendicular to the cross rail 2 and parallel to the supporting surface 19a, b in the direction of the arrow 7 downwards. Thereby, the recess 27 of the hook 26 is shifted over the protrusion 29 of the cross rail 2 in a proper form-fitting manner, wherein an appropriate sliding clearance is provided between the flank 28 of the recess 27 and the flank 30 of the protrusion 29. It is essential that the recess 27 and the protrusion 29 are engaged with each other not only by means of a simple hook connection but also by means of a kind of groove-tongue-connection comprising a sliding fit. The said sliding fit between the holder 5 at its contact surface 15a, b as well as the opposite flank 28 parallel thereto and the cross rail 2 at its supporting surface 19a, b as well as the opposite flank 30 parallel thereto is present over the whole compensating range. Thus, the holder 5 and the cross rail 2 are guided to one another between the maximum positions according to
Additionally, during the second joining motion 41, the snap-fit hook 33 engages into the row 34 of teeth. To this the length of the row 34 of teeth is adapted to the size of the desired tolerance compensation. Depending on the length of the shift, i. e. depending on the deviation from the nominal distances between two adjacent cross rails 2 and/or the holders 5, the snap-fit hook 33 can thereby take on one of several successive joining positions, wherein a grid spacing for the row 34 of teeth of less than one millimeter is provided here. Accordingly, the said snap-fit connection of the snap-fit hook 33 and the row 34 of teeth provides a finely sub-divided arresting possibility effectively inhibiting an unintended shift or a motion play, both in and against the direction of the arrow 7. However, the snap-fit connection allows disassembling such that the snap-fit connection of all four holders 5 can be overcome by using sufficiently high manual force. It is also conceivable to block a motion against the second joining motion 42 and the arrow 7, when using an appropriate asymmetrical design of the tooth flanks, particularly when using a saw tooth profile design. During the second joining motion 41, the latch 35 additionally turns out of the recess 36, preferably in the position, in which the snap-fit hook 33 reaches the first joining position on the row 34 of teeth. After the second joining motion 41, the holder 5 can be shifted either as far as the bottom 32 of the recess abuts against the front side 31 of the protrusion 29 according to
For illustration purposes,
| Number | Date | Country | Kind |
|---|---|---|---|
| 102008027857.2 | Jun 2008 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DE2009/000811 | 6/11/2009 | WO | 00 | 4/5/2011 |
