1. Lightweight Solar Metal Roofing: Summary of Invention: This invention describes a solar panel that has a single mono-crystalline or poly-crystalline silicon solar module or a series of electrically connected mono-crystalline or poly-crystalline silicon solar modules directly attached to a profiled metal sheet. The solar modules do not have glass facings and are light in weight. Background to the Invention: Metal roofing, particularly steel roofing, is widely used in Australia for the roofing of a variety of buildings. Roofing provides a large area of catchment for solar radiation and solar panels mounted on roofs are becoming an Increasingly common site in Australia. By fa.r the most common type of solar panels are those that have a layer of glass on their outer surface. The glass makes the solar panel heavy and relatively fragile and installation somewhat cumbersome. The solar panels can be mounted on tilt racks in order to capture more sunshine or parallel with the pitch of the roof to improve appearance. In either case, mounting assemblies are required for the solar panels and these are attached across the top of the ribs of the profiled metal roofing. Having the solar panels separated from the roofing is beneficial in that it allows cooling of the reverse surface of the solar panel. The efficiency of solar panels in terms of their electrical output decreases with increase in panel temperature. These glass-faced solar panels are usually based on mono-crystalline or poly-crystalline silicon solar cells since these types of solar cells have the highest peak electrical efficiency currently commercially available. A steel roof can weigh as little as 5 kilograms per square metre. and can be used over relatively light structural framing with roofing battens spaced a metre or more apart in warm climates such as Australia where roofing is not normally subject to snow build-up In winter. Glass-faced solar panels can increase that weight by a further 15 kilograms per square metre or more when also taking account of the weight of the mounting assembly. While this weight may not be a problem for some residential roofs where the structural framing has been specified to cope with the weight of concrete tiles, It can become a consideration for other large steel-roofed buildings where the structural framework is designed to cope with the weight of steel sheets and occasional careful foot traffic only. There is an Australia patent application where a solar panel is attached by means of roofing screws to the top of the ribs, that is, the crests of a corrugated steel profile. The solar panel consists of a solar laminate that is bonded to a steel overcapping system. While this does allow air circulation under the solar panel, the extra layer of steel adds additional cost and weight, possibly as much as another 5 kilograms per square metre excluding the weight of the solar laminate. The solar panel overcapping is longer than the specified distance between roofing battens for standard gauge corrugated steel. This necessitates the use of valley fasteners rather than crest fasteners in certain 2. positions under the overcapping if it is to be fitted snuggly over the crests of the corrugations. Valley fasteners do not provide as much security as crest fasteners in terms of water-tightness but this patent application overcomes this by lapping the overcapping under the ridge capping. While this prevents rain water tracking beneath the overcapping it also reduces the number of valleys in the corrugated profile available to drain rainfall evenly off the roof. Features of Invention: This Invention describes a light weight solar panel roofing system that has a single mono-crystalline or poly-crystalline silicon solar module or a series of electrically connected mono-crystalline or poly crystalline silicon solar modules directly attached to a profiled metal sheet that is easily installable or demountable, if necessary, and is readily maintainable. The solar modules of this invention are not glass-faced and are much lighter in weight and more easily handled than glass-faced solar panels, being around 5 kilogram per square metre versus 12 kilograms per square metre or more for the glass-faced panel, excluding mounting assembly. Unlike for the glass-faced panels that require mounting assemblies, the solar module of this invention is attached directly to the top of the ribs of the steel profile using metal fasteners. This not only eliminates the cost of the mounting assembly it also makes attachment of the solar module to the metal profile very simple. Likewise, remounting of the solar module, should maintenance be required, is equally simple. The solar modules of this invention are not faced with glass but faced with high durability plastic like the solar laminate used on the overcapping system. However, they have aluminium or thick plastic backsheets that retain sufficient rigidity to span over the ribs of metal profiles that have regularly repeating corrugations geometry providing the corrugations are closely spaced together. The types of profiles that are expected to comply with this requirement are those with regularly repeating curved or trapezoidal corrugations, for example Custom Orb * or Spandek* or equivalents to them. These profiles provide frequent points of support for this type of solar module. Metal profiles that have valleys that are flat pans considerably wider than the rib sections, are unlikely to be as suitable. The solar modules of this Invention are available In a wide range of widths so that judicious choice of module ensures that the sides of the module conform closely with the ribs of the corrugations so that the module can then be attached by metal fasteners to the tops of those ribs. The solar modules of this invention are also available in a wide range of lengths so that judicious choice ensures that the top and bottom of the module do not encroach on locations of the metal sheet where fasteners will be required to fix it to the roofing battens.
3. The solar modules of this invention have junction boxes on the upper surface or the reverse surface of the module with terminal wires allowing easy quickfit connection one to another to make up an array of modules down the metal sheet. Connection of the terminal wires from one array to another and routing to the central electricity collection point is straightforward to those skilled in the art. It is also desirable to choose a width of solar module that covers most of the width of the sheet in order to maximise the amount of electrical output per roof area. At the same time it is also desirable to choose a width of solar module that leaves part of the sheet uncovered so as to enable access for foot traffic for installation and maintenance. Fixing of the solar module to the metal profile is by means of fasteners through its electrically non-active outer edges. Modules are available with perforations and grommets already incorporated in them for this purpose. The perforations can be over-sized so as to permit some movement of the module in the case of the expansion and contraction of long metal sheets. Unlike for glass-faced solar panels that are fixed to the roofing on-site, it is quite feasible for the solar panel of this invention to be assembled in the factory so as to maximise cleanliness and quality control before transporting to site and installing. It is equally feasible to do the assembly of the panel on-site as part of a new roof installation or as a retrofit over an existing roof. Because the length of the solar modules that form the array on the metal sheet are chosen to avoid fastener lines, there is no need to use valley fasteners as there is with a long overcapping system. The separation between the solar modules down the sheet where the fastener lines occur also allows water to flow beneath them in the valleys of the corrugated profile which allows even drainage off the roof. In summary, this invention exhibits improvements over glass-faced modules and solar steel overcappings in a number of areas; lighter weight that is more compatible with light framed building construction, easier handling, installation and remounting and the possibility of factory assembly as well as site assembly.
4. Example 1: Commercially available 1020mm x 540mm mono-crystalline ETFE faced semi-flexible module attached by means of fasteners to 760mm cover width 0.42mm base metal thickness coated corrugated steel (for example Custom Orb* with or without a colour coating applied to it )which has 11 corrugations and a distance between the crests of adjacent corrugations of 76mm. The module width corresponds to spanning 7 valleys representing about 70% of the cover area of the sheet. Two corrugations remain exposed in the underlap area enabling foot traffic without the necessity to walk on the solar module. The module length is shorter than the maximum distance of 1200mm specified between roofing support battens for this thickness of corrugated sheet. Narrower modules are also possible but at the expense of reducing electrical output per roof area and longer modules are available where the maximum allowable distance between fastener lines is greater for roofing sheets of greater base metal thickness. The plan of the example shows only two solar modules attached to the sheet for convenience. Wiring connections in the example are via double junction boxes mounted on the upper surface of the solar module but other junction box designs and wiring protocols are possible and known to those skilled in the art, Example 2: Commercially available 1435mm x 540mm mono-crystalline ETFE faced semi-flexible module attached by means of rivets or small screws to 700mm cover width trapezoidal corrugated steel(for example Spandek* with or without a colour coating applied to it) which has 9 corrugations. The module width corresponds to spanning 6 valleys representing 77% of the cover area of the sheet. The module length is shorter than the maximum distance of 2400mm specified between roofing support battens for this thickness of this trapezoidal corrugated sheet. Narrower modules are also possible but at the expense of reducing electrical output per roof area and longer modules are theoretically available where the maximum allowable distance between fastener lines Is greater for roofing sheets of greater base metal thickness. The types of junction boxes available and the electrical connections required are as described in Example 1 although this metal profile has more space in the valley beneath the solar module to site the junction box out of view on the reverse surface of the solar module.