NL2004561C2 - Solar panel system, and profile mounting assembly and method of mounting for such a system. - Google Patents

Description

- 1 -

Solar panel system, and profile mounting assembly and method of mounting for such a system 5 The invention relates to a solar panel system for a flat roof and to a profile mounting assembly for use in such a solar panel system as well as to a method of mounting such a solar panel system.

Solar panel systems for a roof, such as a flat roof, 10 are nowadays increasingly in demand, as a result of an increasing need for sustainable energy such as electrical energy generated by photovoltaic cells.

Such a photovoltaic solar panel system is often positioned on a flat, or nearly flat roof, with the solar 15 panels at an inclination relative to the roof and at an orientation facing south when possible. In most cases, multiple parallel rows of solar panels are positioned behind each other, at equal distances chosen in such a way that the rows of solar panels do not cast too much shadow onto each 20 other while still maintaining a relatively dense packing of solar panels on the roof.

One of the requirements for such systems is that they are wind-resistant; even in weather conditions of high wind velocities at the roof level, the solar panels need to remain 25 in place on the roof without being lifted, tilted, shifted or even blown away. This requirement may be met by fixing the system to the roof, but this solution introduces potential damage to the roof, with the possibility of leakage, and is laborious. Another common solution lies in the creation of a 30 construction too heavy to be blown away. However, many modern roofs using profiled steel sheets or light weight sandwich - 2 - panels have a very limited load capacity. Therefore the challenge is to construct the system in such a way that it is wind-resistant at only a low total weight to be added onto the roof .

5 A known solution for lightweight flat roofs consists of a system that has a construction comprising a plurality of parallel beams or profiles and a second plurality of parallel beams or profiles fixed perpendicular to the first plurality; thus, a kind of matrix is constructed. Often in these 10 solutions, the required inclination of the solar panels is realised by additional profiles or triangular shaped subconstructions to support the solar panels. The beams in the matrix have a relatively high bending stiffness and stretch across several solar panels. As a result, the system is 15 stable in comparison with systems in which the solar panels are connected in a looser manner or where the solar panels are not interconnected at all. A matrix construction helps to distribute wind loads over the construction and it prevents individual solar panels to be lifted or shifted and to tip 20 over. This makes such a construction capable of withstanding higher wind velocities with a lower overall weight load onto the roof, thus reducing the need to add additional ballast.

One such a known relatively lightweight and freestanding system on the market is produced by Schueco in 25 Germany under the name of ezFlatRoof 2.0 Mounting System. However, the described solution has the disadvantage that it consists of many different parts and connections to be made during installation, and is therefore costly. Additionally, in many matrix-based systems such as that of Schueco, the 30 first plurality of parallel beams rests directly on top of the roof, therefore blocking the free flow of water over the - 3 - roof. During heavy rainfall, large amounts of water may accumulate between the beams without the possibility to flow away to lower areas. The access weight of this water may form a serious threat to the weight-carrying capacity of the roof.

5 A second known relatively lightweight and freestanding system is produced by HB Solar in Germany under the name of Scirocco. In this system, wind diversion plates, are mounted at an elevated backside of the solar panels, to prevent that wind reaches the bottom side of the solar panels and causes 10 them to tip over. However, in this system the wind diversion plate at the back side of the solar panel has a much steeper inclination angle relative to the roof than the solar panel itself, with as a result that wind coming from the back side of the solar panel will still push the solar panel away 15 relatively easy. It may be argued that when wind diversion plates are to be used in a system, their inclination angle should match the inclination angle of the solar panels as close as possible, in order to prevent the introduction of asymmetry in the wind-sensitivity of the system.

20 The present invention has as a goal to provide a solar panel system for a flat roof and with photovoltaic cells that has a low roof load, is at least as stable with respect to wind as the systems described above and additionally offers reduced costs and/or increased convenience of installation. 25 The invention realizes this goal by a solar panel system according to claim 1.

As a result of the matrix-like arrangement of the profiles and the presence of interconnections that provide stiffness to the arrangement, the stability (in terms of 30 lifting, shifting and tipping over in strong winds) of known systems with a matrix structure is maintained.

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The specific layout of the system according to the invention allows for a mounting method that requires only little effort. Such a mounting method may, for instance, be as follows.

5 As a first step, the base profiles, factory pre-fitted with at least two feet per profile, are put on the roof, parallel to each other at roughly the required distance. Multiple base profiles may be connected to each other to extend the length of one profile row to the required row 10 length of the solar panel system.

Then, as a second step, the carrier profiles, factory-made to a length exactly right to span the required distance between two rows of base profiles, can be easily positioned and then fixed to the base profiles present. The carrier 15 profiles thereby serve to finalise, or fine-adjust, the required distance between the base profiles in a convenient manner. The carrier profiles are shaped in such a way that they can be positioned between the base profiles from above, meaning that if already two or more carrier profiles are 20 connected to base profiles, the next carrier profiles can still be added easily.

A further advantage of the system according to the invention is that less material and less installation labour are required compared to traditional matrix-based systems. 25 This results from the fact that no additional supports are needed for mounting the solar panels and wind diversion plates since these are mounted directly on the carrier profiles. The carrier profiles fulfil multiple functions at once: carrying the solar panels and wind diversion plates, 30 being part of the stable construction (i.e., the matrix) and setting the right distance between the base profiles.

- 5 - it will be clear to persons skilled in the art that 'means that prevent relative rotation between the base profile and the respective carrier profile' refers to constructive elements capable of transferring a bending force 5 from the base profile to the carrier profile. For instance, two surfaces bearing against each other and pulled towards each other by means of a simple hook and lip or nuts and bolts are capable of fulfilling this function. It will also be clear that 'profile' refers to an elongated constructive 10 element, possibly hollow, with a high bending stiffness in relation to its weight. Finally, it is noted that in the present application the term 'perpendicular' refers not only to an angle of exactly 90 degrees but also to slightly deviating angles, such as, for example, 87 or 92 degrees.

15 Beneficial embodiments of the invention are defined in the sub claims 2 through 10. These are directed at even more convenient mounting or improved stability in strong wind conditions. Additionally, the feet will ensure the free flow of water over the roof under the entire system, with as a 20 result reduced risk of a roof collapsing under the weight of rain water or melting water. The feet, especially when made of relatively soft material such as thermoplastic material, will also prevent damage of the roof as could occur when metal profiles would be placed directly on the roof. They may 25 also be used as guides for the exact position where the carrier profiles are to be connected to the base profiles, thus preventing the need for measurements or calculations to be made on the roof and thus further increasing the ease of mounting. Finally, the feet, when made of material with a 30 high friction coefficient, will provide added resistance against translational movement of the system over the roof - 6 - under strong winds .

The invention also concerns a profile mounting assembly according to claim 11. This assembly provides a perpendicular connection between two profiles that is rigid, especially 5 prevents relative rotation and translation between the two profiles. Additionally, this assembly can be supplied to the installation with all required parts for the connection, including bolts, already pre-fitted in the factory. In other words, it enables the realization of a system according to 10 claims 1-10. It should be noted that one interpretation of the phrase 'a hook slidably mounted to the second profile...' is that said hook lies within the perimeter of a hollow second profile; other interpretations are possible, however. Further beneficial embodiments of the profile mounting 15 assembly are defined in claims 12 through 14. These offer increased comfort of mounting.

Finally, the invention relates to a method of mounting according to the claim 15. When a system according to the invention is mounted according to this method, the mounting 20 required relatively little effort, thereby enabling increased mounting time efficiency.

The invention will now be clarified on the basis of a preferred embodiment, referring to the accompanying drawings and solely as an illustration of the invention and not in 25 limitation thereof. In the drawings: - Figure 1 shows a perspective view of a solar panel system according to the invention, with the solar panels and wind diversion plates partly removed for the sake of clarity, - Figure 2a shows a longitudinal section of a carrier profile 30 in an unmounted position, with the hook retracted within the perimeter of the profile, - 7 - - Figure 2b shows a cross-section A-A of the carrier profile and hook in Figure 2a, and - Figure 2c shows a cross-section of a base profile with two carrier profiles mounted on opposite sides of the base 5 profile.

In Figure 1, a system S according to the invention has four base profiles 1 arranged parallel and at equal distances on a flat roof 2, a number of carrier profiles 3, arranged perpendicular to and between the base profiles 1. In Figure 10 1, for the sake of clarity only two of the carrier profiles are indicated by a reference number; this also holds for some other components of the system shown in the drawings. At their ends, the carrier profiles 3 are fastened to base profiles, near the roof, by means of interconnections 4.

15 Each of the carrier profiles 3 has a first inclined section 5, with respect to the horizontal, on which a photovoltaic solar panel 6 is mounted. The carrier profiles contain longitudinal grooves where known mounting clamps can slide in and be fixed onto in such a way that variations in 20 the size of the solar modules (e.g. between various solar panel brands and makes) can be compensated for. The mounting clamps for the solar panels are not shown. Each solar panel 6 is carried by two adjacent carrier profiles 3 at a mutual distance of about half the width of the solar panel at 25 positions at about one-quarter from the edges of the solar panel. In an alternative embodiment of the invention (not shown), the solar panels are carried by carrier profiles positioned in the area between two solar panels, reducing the total number of required carrier profiles to an average of 30 about one per solar panel.

The base profiles have a length that is at least the - 8 - width of one solar panel, possibly longer, or may have a length that is independent of the solar panel dimensions. A small dilation spacing is left between each two subsequent base profiles (not shown).

5 Each interconnection 4 fastens a carrier profile 3 to a base profile 1, in such a manner that the carrier profile 3 cannot rotate or move relative to the base profile 1 about any axis parallel to the longitudinal axis of the base profile. This rotation- and movement-preventing function of 10 the interconnections enables the creation of a highly stable solar panel system S, that will not be affected by wind forces, even in extreme wind conditions.

The carrier profiles 3 have a second inclined section 7 of which the inclination is opposite to that of the first 15 inclined section 5 and serves to carry wind diversion plates 8. In the shown embodiment, the angle of inclination of the second inclined section (for the wind diversion plates) is as low as is possible given the row spacing of the solar panels, thus matching the solar shading angle between two rows of 20 solar panels as close as possible, based on the assumption that the lower the wind diversion plate inclination angle is, the less force the wind will exert on the system.

In the system S, some spacing is left between the wind diversion plates and the solar panels, in order to allow for 25 ventilation of the backside of the solar panels; this serves the electricity production efficiency of the photovoltaic cells in the solar panels.

Each carrier profile is made of at least two hollow aluminium profiles, connected with an angle to each other by 30 means of inserts (not shown). Alternatively, the carrier profiles may be bended out of one piece or may be welded - 3 - together, etc. Additional provisions may be integrated in or attached to the carrier profiles, such as a cable clamp for the solar panel cables.

The base profiles are also hollow and made of 5 aluminium, and they are factory pre-fitted with injection-moulded plastic feet 9 which may have a bottom of a thermoplastic elastomer (TPE), i.e., a thermoplastic rubber, with an increased friction between the system and the roofing material as result. This increases the stability of the 10 system S on the roof with respect to wind forces.

In the embodiment shown, the solar panels are mounted in landscape orientation, but in a different embodiment they may also be mounted in portrait orientation.

Here, the wind diversion plates 8 span the whole area 15 between two rows of solar panels 6, leaving no gangway. The diversion plates 8 can be made of white-painted sheet metal that reflects sunlight onto the solar panels, leading to an increase of the electricity yield of the solar panels. In an alternative embodiment, not shown, the carrier profiles may 20 have a second bend, with a horizontal section near one of their ends. This allows for a gangway.

The wind diversion plates can be mounted by means of mounting elements (not shown) that can be released quickly and easily should they be removed in case of e.g. servicing 25 or maintenance of the solar panels.

Figure 1 shows that ballast material may be added to the system S when the local wind conditions require so, by positioning sheet metal profiles 10 between (some of) the base profiles 1, and resting on these profiles 1. Ballast 30 material e.g. in the shape of street tiles (not shown) is put on top of these sheet metal profiles 10. Said sheet metal - 10 - profiles 10 may also serve as an aid in the positioning of base profiles 1 before the carrier profiles 3 are added.

In Figure 2a and 2b, one end of the carrier profile 3a is shown with hook 11. Each end of the carrier profiles is 5 pre-fitted with such a hook element, made of strong aluminium or stainless steel. This hook has a clearly indicated retracted and extended position: the retracted position (i.e. production-, transport- and pre-mounting position) is with the hook retracted into the carrier profile as shown in 10 figure 2a; the extended position (i.e. the fixed position after mounting) is with the hook locked onto the base profile as shown in figure 2c. The hook is slidable within the perimeter of the carrier profiles from one position to the other and vice versa, resting on profile ribs 12 and 13.

15 Figure 2c shows two carrier profiles 3a and 3b, supporting a photovoltaic solar panel 6 on its first inclined section 5 and a wind diversion plate 8 on its second inclined section 7, and fastened to a base profile 1 resting on top of a foot 9. The base profile 1 is hollow and made of aluminium, and 20 provided with two vertically downward extending profile lips 14 and 15, part of its two opposite side walls 16 and 17, and extending in their lateral directions along the entire base profile 3 length.

The carrier profiles 3a, 3b have slanted heads on both 25 ends that each rest against a respective side wall 16, 17 of the base profile 1 over a large part of the head surface of the respective carrier profile.

A hook extending from one end of the carrier profile 3a or 3b, such as hook 11, can reach into a matching indentation 30 18 and 19 of the base profile 1 and engages a respective profile lip 14, 15 of the base profile 1, pulling the heads - 11 - of the carrier profiles against the wall of the base profile.

The hook 11 is fixed with respect to the carrier profile 3 in either the retracted or the extended position by-means of an Allen bolt 20 that is screwed into a threaded 5 hole in the hook and that extends into one of two holes 21 and 22 corresponding with the retracted and extended positions at the bottom of the carrier profile, thus securing the hook into either position. By unscrewing the bolt in the retracted position of the hook, the tip of the bolt comes 10 away from the hole 21, and the hook can then slide downwards over ribs 12 and 13, aided by gravity, with the bolt moving along a slotted hole 23 made in a top wall of the carrier profile.

At the end of this movement, the hook extends beyond 15 the end of the carrier profile and is loosely positioned into indentation 18 or 19 of the base profile.

When the Allen bolt is then tightened again, the hook comes up until it is firmly pulled against the profile lips 14 or 15 of the base profile, which may be wedge-shaped 20 matching the wedge-shaped tip of the hook, helping to pull the carrier profile head against the base profile side wall 16 or 17. Further tightening of the Allen bolt will now screw the tip of the bolt into the end position hole 22 in the bottom of the carrier profile, which will prevent any future 25 sliding movement of the hook in the carrier profile. After final tightening of the Allen bolt, the whole construction is secured rigidly.

As a result of this construction, the carrier profiles cannot rotate or translate in any direction with respect to 30 the base profile; this provides for a stable solar panel system. Moreover, the two clear retracted and extended - 12 - positions ensure error-free mounting. The retracted position with the hook and bolt assembly completely stowed away in the carrier profiles secures safe transport and avoids the use of loose fixing materials (nuts and bolts) with all their 5 disadvantages (missing items, pieces dropping onto the floor etc.). Finally, because the hooks do not protrude from the carrier profiles in the start position, carrier profiles can be mounted between the base profiles by lowering them from above. They may be mounted one after another even if other 10 carrier profiles are already into place. It also does not matter which of the two hooks at either end of the carrier profile is secured first.

The combination of a carrier profile 3 and a base profile 1 and a hook 11 fastening said carrier profile and 15 said base profile constitutes a profile mounting assembly according to the invention. The hook 11 and its counterpart on the other end of the carrier profile and profile lips 14, 15 and the parts of the profiles bearing against each other constitute two interconnections 4.

20 It will be clear to persons skilled in the art that the embodiment of the solar panel system according to the invention as described above and illustrated in the drawings is suitable for repeated application of the method of mounting according to claim 17. This method will therefore 25 not be clarified.

Variants can be made to the embodiments shown, without leaving the scope of the claims. For example, the carrier profiles may be provided with two or more bends instead of one. Moreover, the flat roof may be slightly inclined to the 30 horizontal.

Claims (16)

Solar panel system for a flat roof, comprising three or more basic profiles arranged at mutual distances parallel to or near said flat roof, - two or more supporting profiles arranged perpendicular to the basic profiles and extending respectively from a first to a second copy of the basic profiles and from a second to a third copy of the basic profiles, - at least one photovoltaic solar panel arranged on at least one support profile, in such a way that the solar panel is inclined with respect to the flat roof, - at least two connections, one connection between 15 said second basic profile lies and one end of one of said two support profiles and another connection lies between said second basic profile and one end of the other of said two support profiles, each of said connections securing the second basic profile to one end of the relevant support profile with midde which are capable of a) preventing mutual rotation between the second basic profile and the relevant bearing profile in order to prevent an axis parallel to the longitudinal axis of the basic profile and b) to prevent displacement between the second basic profile and the respective bearing profile. Solar panel system according to claim 1, wherein said profiles are hollow. 3. Solar panel system as claimed in claim 1 or 2, wherein said means preventing said rotation and shifting are formed by: a) the end of the support profile that rests against a side wall of said base profile over a part of the entire head surface of said support profile and b connector means capable of pulling the end of said support profile against said side wall of said base profile. - 14 - 4. Solar panel system according to claim 3, wherein said connector means comprise a hook that engages both said support profile and said base profile within the circumference of the end of the support profile, or within the extension of this circumference. 5. Solar panel system according to one or more of the preceding claims, wherein one or more supporting profiles have a first part that is inclined with respect to the flat roof, and wherein the at least one solar panel is arranged on said first inclined part of said bearing profile. 6. Solar panel system according to claim 5, wherein one or more supporting profiles have a second part, which has an opposite slope with respect to the flat roof to that of the first part and on which second part one or more wind deflector plates are arranged. 7. Solar panel system as claimed in any of the foregoing claims, wherein at least one of the basic profiles has two or more feet that provide a space between the basic profile and the roof. 8. Solar panel system according to claim 7, wherein at least one of the feet is made of thermoplastic material. 9. Solar panel system as claimed in claim 7 or claim 8, wherein the two or more feet are provided with reference points, which indicate where the bearing profiles are to be positioned in the longitudinal direction of the basic profile. 10. Solar panel system as claimed in any of the foregoing claims, wherein at least two of said base profiles have a lip which extends along one of the relevant side walls thereof, and wherein at least one bearing profile rests on said two lips. 11. Assembly for arranging profiles, in particular for a solar panel system according to one of claims 1 to 10, comprising: - a first profile, - a second profile, positioned perpendicular to the first profile 10. a hook slidably mounted at the second profile between a retracted position in which the hook does not extend beyond the end face of the second profile and an extended position in which the hook extends beyond the end face of the second profile, in which assembly for arranging profiles, in the position of the assembly, the hook is in the extended position and the hook engages on the profile in such a way that the head of the first profile rests against the second profile. 20 12. Assembly for positioning profiles as claimed in claim 11, wherein the hook is provided with screw thread in which a bolt protrudes through a slot-shaped hole in the profile, in which the bolt can be fixed and released from the outside of the second profile. 13. Assembly for arranging profiles according to claim 11 or 12, wherein the second profile comprises a hole in which, in the extended position of the hook, the bolt, when inserted into the hole, secures the hook in the extended position of it. 14. Solar panel system according to any of claims 1 to 10, wherein at least one of said connections is secured by the assembly for mounting profiles according to any of claims 11 to 13. - 16 - 15. Solar panel system according to claim 14, wherein at least one of said bearing profiles is fixed between and to two base profiles that are positioned on or near the flat roof by two assemblies for arranging 5 profiles according to one of claims 7 to 10, wherein in each of the two assemblies the second profile is the at least one of the support profiles. A method for setting up a solar panel system 10 according to any one of claims 1 to 10 and 14 and 15, comprising the steps of: - positioning two or more base profiles parallel on distances on a flat roof, - lowering at least one support profile until it is located between said base profiles without gross adaptation of profile spacing, and - securing the support profiles to the base profiles.