AU2013204713A1 - A solar roof sheet assembly - Google Patents

Abstract

This invention relates to a solar roof sheet assembly, and a roof comprising a plurality of these. The solar sheet assembly comprises an elongate sheet of a substantially v-shaped cross-sectional shape and comprising a pair of side walls, the assembly further comprising a photovoltaic (PV) solar module secured to and extending lengthwise along one of the side walls of the elongate sheet, wherein the side wall supporting the solar module is angled to substantially maximise the amount of sunlight incident on the solar module.

Description

A SOLAR ROOF SHEET ASSEMBLY TECHNICAL FIELD [0001] The present invention relates to roof sheeting for buildings. In a particular form, the invention concerns the integration of solar photovoltaic modules with the roof sheeting. PRIORITY DOCUMENTS [0002] The present application claims priority from: Australian Provisional Patent Application No. 2013900165 titled "A SOLAR ROOF SHEET ASSEMBLY" and filed on 18 January 2013. [0003] The content of this application is hereby incorporated by reference in its entirety. BACKGROUND OF THE INVENTION [0004] Buildings, in particular commercial and industrial buildings, often have large roof areas that present a large catchment area which can be leveraged to harness sunlight for electricity generation. Arrays of solar photovoltaic (PV) modules may be installed onto these roof areas to form a rooftop solar power plant capable of providing sufficient electricity to power the building. [0005] Rooftop solar power plants are preferable to solar farms as they do not require additional land space (and associated security fencing) and are not normally situated in remote areas. [0006] Large-scale rooftop solar photovoltaic (PV) systems have in the past required solar modules to be installed flat to the incline of the existing roof. The problem with this kind of installation is that depending on the latitude of the installation site, the incline of the existing roof is unlikely to be optimal for the solar modules to capture the maximum amount of sunlight throughout the year. It is known that a solar module produces its maximum power output when sunlight is incident on its solar cells at a perpendicular angle (900). To optimise electricity generation, both the orientation (North, South, East, West) and tilt of the solar modules must be carefully selected for a given latitude. In Equatorial environments, the Sun is high in the sky throughout the year whereas in Polar environments the opposite is true. In temperate or sub-tropical environments, the Sun is high in the sky in the summer months and low in the sky in the winter months (for a particular hemisphere). Depending on the geographic location therefore, the optimal orientation and tilt of a solar module will vary. For Sydney, by way of example, at a latitude of 35'S, the optimal orientation of a solar module would be oriented North at a tilt angle of 270 (to the horizontal).

2 [0007] To address the problem of installing a solar module on the incline of an existing roof which may not be at the optimum angle of tilt for the particular latitude, tilt racking may be used. Tilt racks provide a dedicated mounting structure for a solar module and are designed to provide an optimal tilt angle for the given latitude of the installation site. The addition of tilt racks to the roofing structure itself adds considerable expense to the installation process, and detracts from the aesthetic appearance of the roof. [0008] It is against this background and the problems and difficulties associated therewith that the present invention has been developed. [0009] Certain objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. SUMMARY OF THE INVENTION [0010] According to an aspect of the invention, there is provided a solar roof sheet assembly, including: a. an elongate sheet including a base portion and having side walls extending upwardly and outwardly from respective lengthwise edges of the base portion; b. a photovoltaic (PV) solar module secured to and extending lengthwise along one of said side walls of the elongate sheet; c. wherein, the side wall having the solar module secured thereto is angled to substantially maximise the amount of sunlight incident on the solar module. [0011] In one form, the width of the side walls of the elongate sheet is greater than the width of the base portion. [0012] In one form, the elongate sheet is adapted to allow foot traffic for installation and maintenance without contacting the solar module. [0013] In one form, the elongate sheet is shaped to allow air flow beneath a rear surface of the side wall having the solar module secured thereto so as to provide a cooling effect for the solar module. [0014] In one form, the solar module is secured to the side wall with an adhesive or adhesive tape. [0015] In one form, the solar roof sheet assembly is capable of self-spanning at least 20m between building rafters.

3 [0016] In one form, the solar roof sheet assembly is adaptable to optimise the amount of incident sunlight on the solar module for electricity generation at latitudes in the 30 to 50 degree range. [0017] In one form, the side walls of the elongate sheet have distal edge portions that enable adjacent sheets to mate in an interlocking engagement. [0018] In one form, the elongate sheet is produced from a ferrous alloy such as steel. In one form, the sheet is produced by roll forming sheet metal. [0019] In one form, the solar module is a flexible thin film. [0020] According to a further aspect of the invention there is provided a solar roof for a building, including: a. a plurality of solar roof sheet assemblies, each assembly including: i. an elongate sheet including a base portion and having side walls extending upwardly and outwardly from respective lengthwise edges of the base portion; ii. a photovoltaic (PV) solar module secured to and extending lengthwise along one of said side walls of the elongate sheet; b. wherein, the solar roof is configured so that the solar modules secured to the plurality of solar sheet assemblies are substantially North facing and each side wall having a solar module secured thereto is angled to substantially maximise the amount of sunlight incident on the solar module. [0021] In one form, the solar roof provides a single weatherproof skin for the building. [0022] In a further aspect, the invention may be said to reside in a solar sheet assembly comprising an elongate sheet of a substantially v-shaped cross-sectional shape and comprising a pair of side walls, the assembly further comprising a photovoltaic (PV) solar module secured to and extending lengthwise along one of the side walls of the elongate sheet, wherein the side wall supporting the solar module is angled to substantially maximise the amount of sunlight incident on the solar module. [0023] A detailed description of one or more embodiments of the invention is provided below along with accompanying Figures that illustrate by way of example the principles of the invention. While the invention is described in connection with such embodiments, it should be understood that the invention is not limited to any embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, modifications and 4 equivalents. For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention. [0024] The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured. BRIEF DESCRIPTION OF THE DRAWINGS [0025] A preferred embodiment of the present invention will be discussed with reference to the accompanying drawings wherein: [0026] Figure 1 is a perspective view of a solar roof sheet assembly; [0027] Figure 2 is an end view of the solar roof sheet assembly of Figure 1; [0028] Figure 3 is a perspective view of a plurality of solar roof sheet assemblies mounted to a building rafter; [0029] Figure 4 is an end view of the arrangement shown in Figure 3; [0030] Figure 5 is an enlarged view of the interlocking engagement between adjacent solar roof sheet assemblies; and [0031] Figure 6 is a schematic perspective view of a solar roof for a building. DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT OF THE INVENTION [0032] Referring now to Figure 1, there is shown a perspective view of a solar roof sheet assembly 10 according to an embodiment of the invention. The solar roof sheet assembly 10 includes an elongate sheet (or panel) 20 which is roll formed from sheet metal so as to have a cross-sectional profile which is substantially constant throughout a length of the sheet 20. In a preferred form, the sheet 20 is made of steel. [0033] The cross-section of the sheet 20 comprises a base portion 22 (or web) and opposed side walls (or ribs) 24, 25 which extend upwardly and outwardly from respective lengthwise edges 24a, 25a of the base portion 22 as shown in Figures 1 and 2. The sheet 20 forms a generally V-shaped channel profile whereby the width of the side walls 24, 25 is greater than the width of the base portion 22. In 5 the embodiment shown in Figures 1 and 2, the base portion 22 has a trapezoidal corrugated cross section which confers additional strength and rigidity to the sheet 20. In other embodiments, the cross section of the base portion 22 may have an alternative profile. The side walls 24, 25 may be flat as shown or may have a fluted or ribbed profile to provide further structural strength and rigidity. The inclination of the side walls 24, 25 is variable as will be explained in further detail later. [0034] The side walls 24, 25 of the sheet 20 further include distal edge portions 26, 27 that enable adjacent sheets to mate in an interlocking engagement as shown in Figure 5. Distal edge portion 26 is adapted to nestably engage within distal edge portion 27. The distal edge portions may be designed in any manner which permits this functional complementary engagement to occur. [0035] The solar roof sheet assembly 10 further includes a photovoltaic (PV) solar module 30 that is secured to the elongate sheet 20 and extends lengthwise along side wall 24. Preferably, the solar module 30 is a flexible thin film solar module. The preferred module 30 to be used is one based upon Copper, Indium, Gallium, Selenide (CIGS) semiconductor technology. An example of a CIGS module 30, is the SoloPanel SF1 manufactured by Solopower, Inc. This module 30 is flexible, thin, lightweight and more efficient than traditional amorphous-silicon technology in converting sunlight to electricity. [0036] The solar module 30 is secured to the sheet 20 by an elongate strip of doubled sided adhesive tape (not shown) or other suitable adhesive. Such an adhesive tape secures the solar module 30 to the side wall 24 of the sheet 20 substantially across the full width and length of the side wall 24. In practice, as the sheet 20 is fixed to support structure through side walls 24, 25, and fasteners cannot penetrate the solar module 30, a plurality of solar modules 30 (having lengths determined by the fixing interval of the sheet 20 to the support structure) are required to be secured to the side wall 24. [0037] Figures 3 and 4 illustrate a method of mounting the solar roof sheet assemblies 10 to a roof. The solar roof sheet assemblies 10 are designed to span between building rafters without requiring the intermittent support of purlins or girts. The strength and rigidity of the deep V-shaped sheet 20 enables the assembly 10 to self-span at least 20m between rafters. As shown in Figure 3, the elongate sheet 20 of the assembly 10 may be fixed through fastening holes 24b, 25b located in side walls 24, 25. Fastening holes 24b, 25b align with holes 42 in mounting brackets or straps 40 which are mounted to rafter 50 (shown as an I-beam). Mounting brackets 40 are angularly disposed at the same angle to the horizontal as each side wall 24, 25 such that the sheet 20 sits between a pair of brackets 40 (as most clearly depicted in Figure 4) when installed. Fasteners (not shown) secure the sheet 20 to the mounting brackets 40 through the above mentioned fastening holes.

6 [0038] Adjacent solar roof sheet assemblies 10 are joined together or interlocked through engagement of respective distal edge portions 26, 27 as explained earlier and illustrated in Figures 3-5. [0039] Figure 6 shows a solar roof 100 for a building including a plurality of solar roof sheet assemblies 10 joined together and mounted between rafters 50, 60. As shown, the solar modules 30 are mounted on corresponding side walls 24 of each assembly 10 such that each module 30 faces in the same direction. The integration of solar modules 30 with roof sheets 20 in this manner provides a building integrated photovoltaic (BIPV) solution that does not detract from the natural roof lines and is particularly suitable for commercial or industrial roofing, although not necessarily limited to these applications. [0040] An advantage of the solar roof 100 is that it may be readily optimised for maximum electricity generation. In order to maximise electricity generation, the solar modules 30 must be oriented such that the solar cells of each module receive the maximum amount of sunlight throughout the day. As explained previously, a solar module produces its maximum power output when sunlight is incident on its solar cells at a perpendicular angle (900). To optimise electricity generation, both the orientation (North, South, East, West) and tilt of the solar modules must be carefully selected for a given latitude. [0041] The solar roof sheeting assembly 10 of the present invention is adaptable to optimise the incident sunlight for electricity generation at latitudes in the 30 to 50 degree range without having a significant effect on the structural spanning capability of the sheet 20. Angle 0 as shown in Figure 2, may therefore be varied as appropriate for the latitude of the installation site of the solar roof 100. The embodiment shown in Figures 1 and 2 shows a sheet 20 having 0=27'. This is the optimal angle for latitudes such as 35'S where Sydney is located. For cities in the Southern hemisphere, solar modules must be North facing, whereas in the Northern hemisphere modules must be South facing to maximise exposure to sunlight. Therefore for Sydney, by way of example, the optimum orientation for the solar roof sheeting assembly 10 is such that side wall 24 having the solar module secured thereto is North facing and inclined at an angle of 270 from the horizontal. [0042] For installations in the Southern hemisphere, the building to which the solar roof 100 is installed must be aligned East-West (E-W) so that the solar sheet assemblies 10 run longitudinally in the E-W direction. In this way, the side wall 24 having the solar module 30 secured thereto will have a direct Northerly aspect. The present invention therefore motivates the design of buildings oriented in such a way so as to harvest as much energy as possible from the Sun. [0043] As shown in Figure 6, the most typical application of the present invention is for predominantly flat commercial or industrial roofing. The solar roof sheet assembly is particularly 7 suited for buildings in temperate or warm climates which enable the assembly to function as a single weatherproof skin. The assembly 10 therefore performs dual functions. It provides a weatherproof skin for a building while simultaneously providing an advantageous solar catchment facility for electricity generation. [0044] Integrating the solar modules 30 with the deep V-shaped sheets 20 is also advantageous because the sheet 20 allows ready circulation of air for cooling. In particular, air is able to flow beneath side wall 24 which assists in cooling the module 30 which is important in ensuring that electricity conversion efficiency is optimised at all times. The efficiency of solar modules decreases with increasing temperature so the ability to prevent the modules from overheating is important and is an advantage of the solar roof sheeting assembly of the present invention. [0045] A further advantage of the present invention is that it is possible to walk on the pans (i.e. base portion) of the profile for installation and maintenance purposes without touching the solar module. Allowing foot traffic without contacting the solar module minimises the likelihood of inadvertent damage to the modules by installers and technicians. [0046] The sheets 20 will typically be roll formed on site due to their length. After the sheets are roll formed, the solar modules 30 are bonded to them and the assembly 10 is then lifted onto the roof for installation in this pre-assembled form. [0047] It will be understood that the term "comprise" and any of its derivatives (e.g. comprises, comprising) as used in this specification is to be taken to be inclusive of features to which it refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied. [0048] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge. [0049] Although an illustrative embodiment of the present invention has been described in the foregoing detailed description, it will be understood that the invention is not limited to the embodiment disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.

Claims (19)

1. A solar roof sheet assembly comprising an elongate sheet, the sheet comprising a base portion and side walls extending upwardly and outwardly from respective lengthwise edges of the base portion, the assembly further comprising a photovoltaic (PV) solar module secured to and extending lengthwise along one of said side walls of the elongate sheet, wherein the side wall having the solar module secured thereto is angled to substantially maximise the amount of sunlight incident on the solar module.

2. The solar roof sheet assembly of claim 1, wherein the width of the side walls of the elongate sheet is greater than the width of the base portion.

3. The solar roof sheet assembly as in either of claims 1 or 2, wherein the elongate sheet is adapted to allow foot traffic for installation and maintenance without contacting the solar module.

4. The solar sheet assembly of claim 3, wherein the base portion is sufficiently wide between the sidewalls as to provide a walkway.

5. The solar roof sheet assembly as in any one of the preceding claims, wherein the elongate sheet has a substantially v-shaped cross-sectional profile.

6. The solar roof sheet assembly as in any one of the preceding claims, wherein the elongate sheet is shaped to allow air flow beneath a rear surface of the side wall having the solar module secured thereto, and thereby provides a cooling effect for the solar module.

7. The solar roof sheet assembly as in any one of the preceding claims, wherein this is adaptable to optimise the incident sunlight for electricity generation at latitudes in the 30 to 50 degree range.

8. The solar roof sheet assembly as in any one of the preceding claims, wherein this is capable of self-spanning at least 20m between building rafters.

9. The solar roof sheet assembly as in any one of the preceding claims, wherein the side walls of the elongate sheet have distal edge portions that enable adjacent sheets to mate in an interlocking engagement.

10. The solar roof sheet assembly as in any one of the preceding claims, wherein the solar module is secured to the side wall with an adhesive or adhesive tape. 9

11. The solar roof sheet assembly as in any one of the preceding claims, wherein the solar module is a flexible thin film.

12. The solar sheet assembly as in any one of the preceding claims, wherein the elongate sheet is steel.

13. A solar roof for a building comprising a plurality of solar sheet assemblies as claimed in any of claims 1 through 12.

14. The solar roof of claim 11 configured so that the solar modules secured to the plurality of solar sheet assemblies are substantially North facing.

15. The solar roof of claims 13 or 14, wherein this provides a single weatherproof skin for the building.

16. A solar roof sheet assembly comprising an elongate sheet, the sheet comprising a base portion and side walls extending upwardly and outwardly from respective lengthwise edges of the base portion, the assembly comprising a photovoltaic (PV) solar module secured to and extending lengthwise along one of said side walls of the elongate sheet, wherein the side wall having the solar module secured thereto is angled to substantially maximise the amount of sunlight incident on the solar module.

17. A solar roof for a building comprising a plurality of solar roof sheet assemblies, each assembly comprising an elongate sheet including a base portion and having side walls extending upwardly and outwardly from respective lengthwise edges of the base portion a photovoltaic (PV) solar module secured to and extending lengthwise along one of said side walls of the elongate sheet wherein, the solar roof is configured so that the solar modules secured to the plurality of solar sheet assemblies are substantially North facing and each side wall having a solar module secured thereto is angled to substantially maximise the amount of sunlight incident on the solar module.

18. A solar sheet assembly comprising an elongate sheet of a substantially v-shaped cross sectional shape and comprising a pair of side walls, the assembly further comprising a photovoltaic (PV) solar module secured to and extending lengthwise along one of the side walls of the elongate sheet, wherein the side wall supporting the solar module is angled to substantially maximise the amount of sunlight incident on the solar module.

19. A solar roof sheet assembly substantially as herein described and illustrated in the accompanying drawings.