AU2015203159A1 - Photovoltaic assembly - Google Patents

Abstract

Photovoltaic roofing assemblies, systems and methods for installing photovoltaic roofing assemblies are described that offer improvements to the appearance of photovoltaic panels mounted to sheeted roofing structures, particularly corrugated roofing structures, whilst offering protection to panels. The assembly, system and methods are also amenable to retrofit applications and/or repair. Photovoltaic roofing assemblies, systems and methods for installing photovoltaic roofing assemblies comprise battens adapted to support panels and maintain the panels between the battens and beneath the roofline. A cover is fastened to the battens to protect the panels and provide aesthetic continuity to the roof profile. co~

Description

PHOTOVOLTAIC ASSEMBLY FIELD OF THE INVENTION The present invention relates to photovoltaic roofing assemblies and systems and methods for installing photovoltaic roofing panels and assemblies, particularly those that integrate photovoltaic panels within a roof structure and are protected by a cover. BACKGROUND OF THE INVENTION Increases in the price of electricity, consumer preference for renewable or "green" energy sources, the wider availability of renewable energy generating technologies, falls in the cost of renewable energy generating technologies and government incentives for investment in renewable energy generation have increased demand for renewable energy generating systems both in commercial and residential settings. Photovoltaic systems are amongst the most popular renewable energy generating systems. Common photovoltaic modules are rigid units encased in glass or similar fragile materials and are framed for mounting. Such modules are often either roof mounted or mounted to building walls where they gain the greatest exposure to solar irradiation. Systems of this kind are commonly referred to as Building Applied Photovoltaics (or BAPV). While BAPV systems are low in cost and are amenable to use in retrofit installations they suffer from several shortcomings. Modules are fragile; they degrade over time from exposure to the elements and are susceptible to damage from weather events such as hailstorms or damage caused by fallen branches and the like. Further, modules require frequent external cleaning in order to perform optimally, and are often unsightly and can adversely impact the architectural merit or general aesthetic of the building, in some cases contravening local heritage laws and regulations. 1 2 Building Integrated Photovoltaics (or BIPV) are incorporated into building materials, such as roofing tiles, sheeting or wall cladding as they aim to reduce the aesthetic impact of photovoltaic modules. The following examples of prior art photovoltaic systems are mere public knowledge and are not to be construed as forming part of the common general knowledge in the art. Thin, flexible photovoltaic cells used in BIPV systems, such as those described in DE 19912743 Al (Bock M, 2000), CA 2095827 (Nath P and Laarman TD), CA 1289618 (Laaly H), WO 2005/124892 A2 (Faust T), WO 2010/007546 A2 (Chevrier JH and Salasca 0) and CH 202000579 (Lin J), are typically integrated into flexible polymer roofing membranes for use in multi-skinned rooves or integrated into building facades and glazing, offering particular advantages for use within curved building materials or on curved surfaces. Currently, such systems are rarely cost competitive with traditional BAPV systems due to the cost of manufacture of units, the cost of specialised labour for installation, as well as the cost of replacement of existing building componentry with componentry suitable for photovoltaic integration. Therefore these systems are most often integrated into the customised componentry of new buildings and rarely offer a feasible retrofit solution. BIPV roofing systems that integrate low cost hard photovoltaic panels within a roof structure are described in US 2004/0123550 Al (Hartman PH, 2004), WO 2009/081439 A2 (Bonomi G, 2009) and FR 2920452 Al (Berret JT, 2009). Each of these solutions requires the installation of a complete custom roof structure (or significant roof section) including a customised batten and rafter system adapted for receiving a specified panel. As with other BIPV systems, these systems are usually suited to new builds in which the roof supports may be specified in accordance with the desired BIPV system. Accordingly, such BIPV systems are rarely suitable as a retrofit solution. Replacement and repair of hard, fragile panels can be quite difficult in these systems. 2 3 Attempts to modularise BIPV systems to overcome some of these issues are described in US 2010/0018569 Al (Mitchell K and Brant S, 2010), AU 6437680A (Oertel H and Rapp B), GB 2448920A (Dick, M), JPH 10183880 (Masaaki K and Hirosh W), CH 609441 A5 (Courvoisier, JC and Meylan JL) US 2008/0302031 Al (Bressler et. al.) and WO 02/101839 Al (Mucci P). These documents describe roofing systems composed from transparent or translucent hardened roofing tiles comprising photovoltaic cells integrated therein. US 2004/0011354 Al (Erling PS, 2004) provides a solar panel framing system constructed such that the solar panel can be used in place of roofing tiles. These tile-like solutions, however, do not overcome existing difficulties in the use of solar panels with corrugated rooves which are very common and characteristic in many Australian heritage and contemporary buildings; and are also increasingly used in other parts of the world. The present invention seeks to overcome the difficulties with prior art BAPV and BIPV systems by providing a photovoltaic roofing assembly, a photovoltaic roofing system, a method for installing at least one photovoltaic roofing panel, and a method for installing a photovoltaic roofing assembly adapted to preserve the aesthetic appearance of sheeted roofing structures, in particular corrugated roofing structures, whilst offering protection to costly and fragile solar panels. The assembly, system and methods are amenable to retrofit applications and/or repair. Certain objects and advantages of the present invention will become apparent from the following description taken together with the accompanying drawings, which by way of illustration and example, disclose several embodiments of the present invention. SUMMARY OF THE INVENTION In a first aspect, the present invention comprises a photovoltaic roofing assembly for installing one or more photovoltaic panels within a roofing structure comprising: One or more photovoltaic panels; Two or more battens wherein each batten comprises 3 4 a support portion, and a body portion; and A substantially transparent cover; Wherein the battens are substantially parallel, the one or more photovoltaic panels is supported between the battens, and the cover is fastened to the battens in a substantially parallel plane to the one or more photovoltaic panels. In a second aspect, the present invention comprises a photovoltaic roofing system for installing one or more photovoltaic panels within a roofing structure comprising: One or more photovoltaic panels; Two or more battens wherein each batten comprises a support portion, and a body portion; and A substantially transparent cover; Wherein the battens are installed within the roofing structure substantially parallel to one another, the one or more photovoltaic panels is supported between the battens and the cover is fastened to the battens in a substantially parallel plane to the one or more photovoltaic panels. As used herein, the term "roof" and its derivatives such as "roofs" and "roofing" when used alone or with other phrases such as "roofing structure" and "roof frame" will be understood to include all typical elements of a roof structure including, but not limited to, the roof surface material (e.g. roof tiles or roof sheet cladding), all elements of the roof frame (e.g. roof battens, rafters, beams and joists) and other structural elements physically residing in the space between the ceiling of a building and the roof surface. In preferred photovoltaic roofing assemblies or systems of the invention, the one or more photovoltaic panels are supported by the support portion of the batten and abut with the body portion of the batten. In a preferred form, a substantially transparent cover according to the invention includes covers formed of a hardened material, for example, foamed polycarbonate 4 5 homopolymeric materials such as the polycarbonate sheeting manufactured by Palrum and marketed as SUNTUF*. Other preferred hardened materials include polypropylene based materials or those formed of polyethylene, acrylic, glass, polyvinyl chloride (PVC) and the like or composites thereof. Preferred substantially transparent covers may also include tints and/or materials that alter the aesthetic qualities of the material or light qualities of radiation transmitted therethrough (e.g. to achieve partial or selective filtration of wavelength). Thus, preferred substantially transparent covers may include light absorbing materials, in particular UV absorbers or heat absorbing materials. Preferably, the substantially transparent cover is formed of sheet cladding. Preferred sheet cladding may be a simple flat sheet; however, more preferably, the substantially transparent cover is corrugated. More preferably still, the sheet cladding comprises a profile such as miniorb, rib and pan, square corrugated, concealed fixed, flat pan or similar. In a preferred form, the substantially transparent cover comprises sinusoidal corrugations. Preferably, the sinusoidal corrugations are between about 5mm and about 20mm in height. Most preferably, the sinusoidal corrugations are about 17mm in height. In preferred forms of the invention the substantially transparent cover is removable. This is preferably achieved by a reversible means of fastening the substantially transparent cover to the battens, such as by nailing, screwing, riveting and the like. Most preferably, the substantially transparent cover is fastened to the battens by two or more metal sheet screws. Preferred forms of the invention comprising one or more photovoltaic panels preferably comprise a non-flexible photovoltaic panel. Preferred non-flexible photovoltaic panels include panels comprising a set of connected solar photovoltaic modules or panels 5 6 comprising a set of photovoltaic cells electrically connected and mounted on a non flexible supporting structure. Examples include panels formed from crystalline silicon modules and panels formed from rigid thin-film modules, such as DAQO monocrystalline panels (e.g. DQ190MFAa/b), Phono Solar monocrystalline panels (e.g. Diamond/Onyx 190-210 Watt), Sollatek Multicrystalline (polycrystalline) panels (e.g SP175-PS), and Panasonic hybrid thin layer panels (e.g. HIT® premium solar panel). Preferred forms of the invention comprise rigid photovoltaic panels. Rigid panels may offer certain aforementioned advantages of BAPV systems (e.g. low cost, ease of installation, etcetera); however, according to the invention, they are incorporated into assemblies and systems that may also offer certain aforementioned advantages of BIPV systems (e.g. improved aesthetic qualities). In a preferred form, the one or more photovoltaic panels is between about 10mm and about 90mm in width. Preferably, the one or more photovoltaic panels is about 35mm in width. Preferably, assemblies and systems according to the invention comprise one or more packers for narrowing a gap between the photovoltaic panel(s) and the substantially transparent cover. One or more packing strips or packing blocks may be positioned between the photovoltaic panel and the cover. More preferably, the packing strips or packing blocks are constructed from foam, rubber or timber. In a preferred form, the two or more battens according to the invention are fabricated from formed metal and the support portion and body portion of the battens are integrally formed. The body portion of the battens generally provides the height of the batten such that the photovoltaic panel abuts with the body portion of the batten, while the support portion supports the photovoltaic panel from beneath. 6 7 Accordingly, in a preferred embodiment the two or more battens according to the invention are substantially omega shaped. In a further preferred form, the two or more battens according to the invention comprise a profile substantially as illustrated in Figure 5. Preferably, the battens are between about 10mm and about 90mm in height. Most preferably the battens are about 40mm in height. Preferably, the support portion of the battens measures between about 10mm and about 20mm in depth. Most preferably, the support portion of the battens measures about 17mm in depth. In a third aspect, the present invention comprises a method for installing one or more photovoltaic panels within a roofing structure comprising multiple substantially parallel rafters, wherein the method comprises the steps of: a. Fixing two or more battens substantially perpendicularly to the rafters wherein the two or more battens comprise a support portion and a body portion and the support portion is in contact with said rafters; b. Positioning each photovoltaic panel between a pair of battens whereby the panel is supported by the support portion of the batten and abuts with the body portion of the batten; and c. Fastening a substantially transparent cover to the body portion of the battens in a substantially parallel plane to the photovoltaic panel(s). As used herein, the term "roof frame" will be understood to comprise all structural elements within the roof of a building including, but not limited to, the battens, rafters, joists, props, beams, purlins and the like. In a fourth aspect, the present invention comprises a method for installing a photovoltaic roofing assembly within a roofing structure wherein the roofing structure comprises a sheet clad batten and rafter roof frame, and wherein the method comprises the steps of: a. Removing the sheet cladding and battens from the roofing structure; and b. Installing one or more photovoltaic panels according to the method of the third aspect. 7 8 Preferably, each photovoltaic panel of the third and fourth aspects is positioned adjacent to the body portion and is supported from beneath by the support portion of the battens. Photovoltaic panels installed according to methods of the invention are preferably installed in a grid-like arrangement comprising rows and columns. In preferred methods of the third and fourth aspects, the two or more battens are fixed to the rafters at spacing intervals of between about 700mm and about 1100mm. More preferably, the two or more battens are fixed to the rafters at spacing intervals of about 870mm. In a preferred form of the invention of the third and fourth aspects, the substantially transparent cover is substantially coplanar with the roof sheet cladding. Preferred placement of the substantially transparent cover with respect to the roof sheet cladding may provide aesthetic continuity to the roof surface. Preferably, the substantially transparent cover prevents the photovoltaic panels from protruding above the roof surface. Preferred methods of the third or fourth aspects comprise the step of placing one or more packing strips or packing blocks at a perimeter of the photovoltaic panel between the photovoltaic panel and the cover prior to step b. Preferably, the substantially transparent cover comprises a substantially identical profile to the roof sheet cladding. Preferably, the substantially transparent covers is fixed in lapping contact with the roof sheet cladding. In a preferred method, the substantially transparent cover is formed of corrugated sheet cladding. Preferably, the roof sheet cladding is formed of corrugated sheet cladding. In further preferred methods the roof sheet cladding and the substantially transparent cover comprise sinusoidal corrugations. 8 9 Preferably, the substantially transparent cover is removable. In preferred methods of the third and fourth aspects, the substantially transparent cover is fastened to the body portion of the battens by a reversible means of fastening, such as by nailing, screwing, riveting and the like. Most preferably, the substantially transparent cover is fastened to the battens by two or more metal sheet screws. In another preferred form, a method according to the invention comprises the step of fixing a flashing in lapping contact with an edge of the substantially transparent cover. The invention now will be described with reference to the accompanying drawings together with the Examples and the preferred embodiments disclosed in the detailed description. The invention may be embodied in many different forms and should not be construed as limited to the embodiments described herein. These embodiments are provided by way of illustration only such that this disclosure will be thorough, complete and will convey the full scope and breadth of the invention. BRIEF DESCRIPTION OF THE FIGURES The present invention will be further disclosed with respect to several illustrative embodiments of the invention which are described with the assistance of the following drawings wherein: Figure 1 is a perspective view of a roofing section illustrating a photovoltaic assembly installed in a roofing area and showing a cut away area of roof sheeting; Figure 2 is a plan view of a roofing section illustrating several installed rows of photovoltaic panels; 9 10 Figure 3 is side sectional view of an installed photovoltaic roofing assembly along the length of a rafter illustrating the photovoltaic roofing assembly; Figure 4 is a side sectional view of an installed photovoltaic roofing assembly along the length of a metal batten; and Figure 5 is a sectional view of a metal batten illustrating the batten profile and geometry. DETAILED DESCRIPTION OF THE INVENTION According to a first embodiment of the invention, Figure 1 shows a roofing section comprising a photovoltaic roofing assembly retrofitted in an area of a roof. Figure 1 illustrates a typical corrugated metal roof structure supported by a timber rafter and batten frame. Figure 1 depicts a cut-away section showing the substructure of the roofing frame comprising a series of sloped timber rafters 10 forming a gable; and a series of longitudinal battens 12 of 40mm height and 40mm depth spanning the length of the roof and fixed to the rafters from above with 2x12x40 T17 fasteners (Steeline). Corrugated roofing sheets 14 (Bluescope Lysaght Custom Orb 762mm span 16mm corrugations) are fixed to the battens 12 using 12-14x35 metal Teks Hi-Grip Hexagonal Head metal fasteners (Bluescope Lysaght). Solar panels 16 are installed in an area of the roof only. They are held in place by retrofitted metal roofing battens (Steeline 40mm metal roof battens made from Bluescope Steel Hi-Tensile TrueCore 0.55mm steel) (not shown) that run between each row of solar panels. The solar panels are in turn fixed in place by clear corrugated polycarbonate sheets 18 (Palrum Suntuf clear corrugated sheets of 860mm span and 17mm corrugations) which substitute the corrugated roofing sheets 14 in the area above the panels 16. Polycarbonate sheets 18 are fixed to the metal battens by 12g 50mm Clearfix Roofing Screws (Suntuf). Notably, the corrugated roofing sheets 14 and clear corrugated polycarbonate sheets 18 are formed with corrugations of near identical geometry to 10 11 ensure that the retrofitted polycarbonate sheets provide a weather-proof seal when installed. Figure 2 illustrates a further embodiment whereby an entire roofing section of a corrugated metal roof has been replaced with the photovoltaic roofing assembly according to the invention. Corrugated roofing sheets 14 have been removed at the second sheet from ridge capping 20 at the crest of the roof to gutter flashing 22. Rows of solar panels 16 are placed between retrofitted metal roofing battens 24 (Steeline 40mm metal roof battens made from Bluescope Steel Hi-Tensile TrueCore 0.55mm steel) and are fixed in place by securing clear corrugated polycarbonate sheets 18 over the solar panels 16 as described earlier. The section of roof replaced with the photovoltaic roofing assembly is maintained weather-proof by retaining the whole or a portion of the sheet adjacent to ridge capping 20 and gutter flashing 22. Alternatively, the adjacent sheets may be replaced by 'weathering' a new replacement sheet adjacent to ridge capping 20 to prevent wind driven rain from being up the sheet and under the ridge cap. Typically, clear corrugated polycarbonate sheets such as SUNTUF* (also sold as PALTUF®, PALSUN®, PALSUN* FR, PALGARD

TM

, SunSky*, SUNOPAK

TM

, DYNAGLAS®, SUNLITE®, Thermaglas®, SUNPAL®, SUNGLAZE

TM

, PALTILE

TM

, SUNTOP®, SUNSPHERE

TM

, EdgeLock T M and Chair-Mat) manufactured from solid and foamed polycarbonate homopolymer sheets by Palrum are preferred; however, roofing sheets of any profile such as miniorb, flat sheets, rib and pan, square corrugated, concealed fixed, or flat pan profiles may also be used. Sheeting of a similar or identical profile to the existing roofing material provides the combined advantages of aesthetic continuity with the existing roofing sheets whilst sealing the roof without the need to install additional flashings or use sealants between sheets. Further, sheets may be constructed from alternative materials such as polypropylene, polyethylene, acrylic, glass, PVC and the like and may also include tints or other materials that alter the aesthetic qualities of the material or light qualities of radiation transmitted therethrough (e.g. to achieve partial or selective filtration of wavelength or a dampening of heat passing therethrough). 11 12 Figure 3 provides a side sectional view of the first embodiment along the length of a sloped timber rafter 10. Two rows comprising solar panels 16 (DAQO DQ190MFAa/b) measuring 1580mm in height, 808mm in length and 35mm in width are installed in a lengthwise orientation between three rows of metal battens 24 of 40mm height and 40mm-56mm depth spaced at 870mm intervals. Solar panels 16 are supported by the lip of metal batten 24 and are secured in place by clear polycarbonate sheets 18 positioned in an overlapping manner above the solar panels 16 and fixed to metal battens 24 using metal screws 26 (12g 50mm Clearfix Roofing Screws, Suntuf). Panels 26 are also fixed to the lip of metal battens 24 from beneath using small hex metal fixing screws using at least six screws per panel (Suntuf). Existing roofing sheets 14 and clear polycarbonate sheets 18 are positioned to overlap from the crest of the roof in sealing engagement using metal screw 26 to allow water to be directed down the slope of the roof and into the existing roof gutter 28. Existing timber battens 30 and gutter flashings 32 remain in place in the retrofitted arrangement of the first embodiment. It is envisaged that solar panels of various dimensions may be used in place of solar panels 16. To accommodate the dimensions of alternative panels, the interval spacing between metal battens 24 may be adjusted. Where thinner panels are used, packing materials (e.g. timber or foam packing strips or blocks) may be used around the perimeter of the panel to create a tighter seal between the solar panel 16 and polycarbonate sheet 18; however, it is envisaged that in most cases support from metal battens 24 will be all that is required. It is envisaged that persons skilled in the art will be well versed in the local regulations and by-laws that specify the minimum requirements for roof construction, particularly with regard to batten dimensions and batten interval spacing. While a retrofitted photovoltaic roofing assembly comprising only three columns and two rows of solar panels (six panels in total) is illustrated in Figures 1 and 2, it is anticipated that more rows or columns may be readily incorporated into a roofing area by repeating the structural elements of the system as described. Alternatively, fewer rows or columns 12 13 of the above photovoltaic roofing assembly may be installed for placement within a smaller roofing area. The photovoltaic roofing assembly described herein may even be configured to accommodate a single photovoltaic panel. The side sectional view illustrated in Figure 4 shows a section across the length of a metal batten 24 supporting two solar panels 16 configured according to the first and second embodiments. The Figure 4 photovoltaic roofing assembly is installed on pre-existing timber rafters 10 and metal batten 24 is shown lengthwise whereby the two solar panels 16 are supported by the lip 34 of metal batten 24. The panels are held in place between rafter 10 and protective polycarbonate sheeting 18. Lengths of clear corrugated polycarbonate sheet 18 and corrugated roofing sheets 14 are lapped to at least one and a half corrugations to ensure the weather-proof sealing of sheets, and are affixed in this configuration using metal screw 26. It is anticipated that persons skilled in the art will be well versed on the lapping distance required for sheets of alternative profiles to provide an adequate seal and also to comply with local building codes. Figure 5 illustrates the profile and geometry of metal batten 24 according to embodiments of the invention. Metal batten 24 is generally omega shaped whereby the surface 24a of the metal batten is flattened and sides 24b and 24c of the metal batten extend outward at an angle. The metal batten comprises an opening 24d at its widest part, defined by lip 34. The metal battens of the embodiments described herein comprise a 40mm surface 24a, 40mm sides 24b and 24c, a 56mm opening 24d and a 16mm lip 34 extending from each side of the opening. It will be appreciated by persons skilled in the art that the geometry and profile of metal batten 24 may vary, particularly where it must correspond with the geometry of existing timber battens or solar panels or to meet requirements prescribed by local building codes. Photovoltaic roofing assemblies according to the embodiments of the invention were installed by initially identifying an area of a roof surface that maximises photovoltaic panel efficiency, that is, on a wide flat area of the roof that is North facing (for structures located in Australia). 13 14 In preparation for installation, existing sheet metal screws and corrugated roof sheets are removed from the area in which the photovoltaic roofing assembly is to be installed. The wooden battens of existing roof substructures are also removed from the area. Figure 1 shows a smaller area installation wherein existing corrugated roofing sheets 14 and existing battens 12 are removed to only expose the area in which the photovoltaic assembly is to be installed. Larger roof section installations depicted in Figure 2 are prepared by removing complete lengths of corrugated roofing sheets 14 commencing at the second sheet from the crest of the roof to the gutters. The roofing sheets adjacent to the ridge capping 20 are retained to maintain weatherproofing around the ridge capping, and the gutter flashing 22 is left intact. Battens 12 beneath the area in which solar panels 16 are to be installed are removed. For ease of installation, existing lengths of sheeting adjacent to flashed or sealed edges (e.g. sloping drip edges or valleys) are left intact where possible. For roof area and roof section installations, sheeting and battens are removed to the nearest rafter at both sides of the installation area, and the nearest batten above and below the installation area. For installations in new buildings, these preparatory steps are not required as roof battening and cladding are usually not undertaken prior to photovoltaic panel installation. A common photovoltaic panel of 1580mm height, 808mm length and 35mm width (DAQO DQ190MFAa/b) has been selected for integration into the Figure 1 and Figure 2 photovoltaic roofing assemblies. Metal battens 24, as depicted in Figure 5 and as described earlier, are installed to replace the pre-existing battens (for roof area and roof section installations). A first metal batten is fixed 870mm from the furthest point of the uppermost existing batten in the exposed area using batten screws (2x12x40 T17 fasteners, Steeline) to secure the metal batten to the underlying rafters. Additional battens are fixed at 870mm intervals thereafter in a similar fashion. Solar panels 16 are rotated 90 degrees for placement in a lengthwise orientation. The first solar panel is placed to rest between two metal battens 24 on the metal batten lip 34 of 14 15 the two battens, with a 3mm gap allowance between the panel and the sides 24b and 24c of the two battens. Where panels less than 808mm in length are used, metal battens 24 may be fixed at narrower intervals than the specified 870mm interval. The spacing interval between battens is positioned to allow the solar panel to be placed between the metal battens such that it is supported on both sides by the metal batten lip 24. It will be apparent to persons skilled in the art to allow an interval between battens that is compliant with local by-laws and regulations. Clear corrugated polycarbonate sheets 18 (SUNTUF* manufactured by Palrum), of near identical profile, width and length to the existing corrugated roofing sheets, are provided to cover the solar panels 16. Polycarbonate sheets 18 are placed over the solar panels in alignment with the existing corrugated roofing sheets and are positioned to achieve a sealing lap down the slope of the roof (shown in Figure 3). Adjacent polycarbonate sheets are positioned to lap with new and existing corrugated roofing sheets by at least one and a half corrugations (shown in Figure 4) and are fixed at every rib on every row using screws and washer supports (12g 50mm Clearfix Roofing Screws, Suntuf) according to the manufacturer's recommendations. Solar panels 16 are laid side by side one row at a time. For small installations such as that illustrated in Figure 1, installation generally commences from the side where the new polycarbonate sheets achieve a sealing lap with the existing corrugated roofing sheets. Thereafter, sheets are sequentially laid and fixed to avoid excessive foot traffic on the clear polycarbonate sheeting. For installations in which the new polycarbonate sheets and the existing corrugated roofing sheets cannot achieve a sealing lap (e.g. where the profile of new and existing sheets is non-identical), it may be necessary to flash the join between the new polycarbonate sheets and the existing corrugated roofing sheets. 15 16 Electrical connections are made to connect panels to each other and the power grid which is assisted by the consistent orientation of panels across rows and columns. It is recommended that a roof venting, such as a 'whirlybird' (e.g. 300mm Windmaster Roof Vent, CSR), be installed in the roofing structure to dissipate heat, particularly in instances where six or more panels of the type described above are installed in a roof. If many panels are fitted in a single installation, venting should be installed in a roofing structure at a ratio of one vent for every six panels installed. Maintenance, replacement and repair of the protective polycarbonate sheets 18 or the solar panels 16 can be readily undertaken by removing the screws and washer supports that fix the damaged polycarbonate sheets or the sheets covering the damaged solar panels. Solar panels can then be replaced where required and reconnected to adjacent panels. Polycarbonate sheets may be replaced in alignment with the adjacent sheets and should be carefully positioned to achieve a sealing lap down the slope of the roof and with adjacent sheets. The polycarbonate sheets may then be fixed as described earlier using screws and washer supports. It is indeed intended that the scope of the invention should be determined by proper interpretation and construction of the appended claims and their legal equivalents, as understood by those skilled in the art relying upon the disclosure in this specification and the attached drawings. It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Nor is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that various modifications can be made without departing from the principles of the invention. Therefore, the invention should be understood to include all such modifications in its scope. Throughout the specification and the claims that follow, unless the context requires otherwise, the terms "comprise" and "include" and variations such as "comprising" and 16 17 "including" will be understood to include a stated integer or group of integers, but not to the exclusion of any other integer or group of integers. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of each claim of this application. 17

Claims (23)

1. A photovoltaic roofing assembly for installing one or more photovoltaic panels within a roofing structure comprising: One or more photovoltaic panels; Two or more battens wherein each batten comprises a support portion, and a body portion; and A substantially transparent cover; Wherein the battens are substantially parallel, the one or more photovoltaic panels is supported between the battens, and the cover is fastened to the battens in a substantially parallel plane to the one or more photovoltaic panels.

2. A photovoltaic roofing system for installing one or more photovoltaic panels within a roofing structure comprising: One or more photovoltaic panels; Two or more battens wherein each batten comprises a support portion, and a body portion; and A substantially transparent cover; Wherein the battens are installed within the roofing structure substantially parallel to one another, the one or more photovoltaic panels is supported between the battens and the cover is fastened to the battens in a substantially parallel plane to the one or more photovoltaic panels.

3. The photovoltaic roofing assembly or system of claim 1 or 2 wherein the one or more photovoltaic panels is supported by the support portion of the batten and abuts with the body portion of the batten.

4. The photovoltaic roofing assembly or system according to any one of claims 1 to 3 wherein the substantially transparent cover is formed of a hardened material. I 2

5. The photovoltaic roofing assembly or system of claim 4 wherein the substantially transparent cover is formed of sheet cladding.

6. The photovoltaic roofing assembly or system of claim 5 wherein the substantially transparent cover is corrugated.

7. The photovoltaic roofing assembly or system of claim 6 wherein the substantially transparent cover comprises sinusoidal corrugations about 17mm in height.

8. The photovoltaic roofing assembly or system according to any one of claims 1 to 7 wherein the substantially transparent cover is removable.

9. The photovoltaic roofing assembly or system according to any one of claims 1 to 8 wherein the substantially transparent cover is fixed to the battens by two or more metal sheet screws.

10. The photovoltaic roofing assembly or system according to any one of claims 1 to 9 wherein the one or more photovoltaic panels is a non-flexible photovoltaic panel.

11. The photovoltaic roofing assembly or system of claim 10 wherein the at least one photovoltaic panel is about 35mm in width.

12. The photovoltaic roofing assembly or system according to any one of claims 1 to 11 wherein the two or more battens are fabricated from formed metal and the support portion and the body portion of the battens are integrally formed.

13. The photovoltaic roofing assembly or system of claim 12 wherein the two or more battens are substantially omega shaped.

14. The photovoltaic roofing assembly or system according to any one of claims 1 to 13 further comprising one or more packers. 2 3

15. A method for installing one or more photovoltaic panels within a roofing structure comprising multiple substantially parallel rafters, wherein the method comprises the steps of: a. Fixing two or more battens substantially perpendicularly to the rafters wherein the two or more battens comprise a support portion and a body portion and the support portion is in contact with said rafters; b. Positioning each photovoltaic panel between a pair of battens whereby the panel is supported by the support portion of the batten and abuts with the body portion of the batten; and c. Fastening a substantially transparent cover to the body portion of the battens in a substantially parallel plane to the photovoltaic panel(s).

16. A method for installing a photovoltaic roofing assembly within a roofing structure wherein the roofing structure comprises a sheet clad batten and rafter roof frame, and wherein the method comprises the steps of: a. Removing the sheet cladding and battens from the roofing structure; and b. Installing one or more photovoltaic panels according to the method of claim 15.

17. The method of claim 15 or 16 wherein each photovoltaic panel is positioned adjacent to the body portion and is supported from beneath by the support portion of the battens.

18. The method according to any one of claims 15 to 17 wherein the substantially transparent cover is substantially coplanar with the roof sheet cladding.

19. The method of claim 18 wherein the substantially transparent cover comprises a substantially identical profile to the roof sheet cladding.

20. The method of claim 19 wherein the substantially transparent cover is fixed in lapping contact with the roof sheet cladding. 3 4

21. The method of claim 20 wherein the roof sheet cladding is formed of corrugated sheet cladding.

22. The method according to any one of claims 15 to 21 wherein the substantially transparent cover is formed of corrugated sheet cladding.

23. The method according any one of claims 15 to 22 wherein said method further comprises the step of fixing a flashing in lapping contact with an edge of the substantially transparent cover. 4