SOLAR COLLECTOR PANEL

Abstract: Solar panel (1) comprising an absorber element (2), a heat-insulating insulation element (3) placed between the absorber element (2) and an underlayer, and a frame structure (4) surrounding the insulation element (3) and the absorber element (2). The invention is characterized in particular in that said insulation element (3) and said frame structure (4) are integratedly formed into an essentially box-shaped, self-supporting base element (5) having a recess (7) to accommodate said absorber element (2), which base element (5) consists in the main of a foamed plastic material. The solar panel (1) preferably also comprises a transparent covering sheet (6) placed over said absorber element (2).

Description: Solar collector panel TECHNICAL FIELD: The invention relates to a solar panel of the type that is intended chiefly for mounting for example on the roof of a house or other building. The solar panel can be used singly in this connection or - as is normally the case - in conjunction with several solar panels of the same or a similar type. In particular, the invention relates to a solar panel of the so-called flat type, which comprises an absorber element lying in a surrounding frame structure and applied to a heat-insulating insulation element and covered by a transparent covering sheet on the side of the solar panel facing towards the sun. The absorber element is preferably, but not necessarily, of the type that is designed to be flowed through by a heat-bearing liquid, usually water, or water with an anti-freeze admixture. BACKGROUND: Solar panels of the type stated by way of introduction have been known in themselves for a long time. During the 1970s and 1980s a succession of different solar panels was constructed and used as a result of the intensive energy debate which took place during this period with regard to alternative renewable sources of energy. Many of the solar panels fitted during this period were manufactured in relatively small production series in an often unprofessional manner, which in time caused problems with water leakage amongst other things. Another problem with known solar panels is that, as a result of their conventional construction using heavy surrounding frame structures in metal or timber, and insulation elements of mineral wool, they are so heavy that each solar panel has to be lifted up onto a house roof, for example, by means of a hoisting crane. This situation results in high handling costs at the same time as the many constituent parts of the solar panel make the sales price too high for sufficiently large demand, which gives rise to large-scale production of solar panels, to be built up. Efforts have therefore been made with the aim of reducing the weight and the cost of individual solar panels, amongst other things by manufacturing the insulation element lying in the main under the absorber element of a lighter material. An example of such a solution is described in German patent specification DE 42 32 367 A1, in which an insulation element is executed in a hard and rigid plastic foam, even if a mineral wool layer continues to be used in combination with the plastic foam layer. The plastic foam element is sufficiently rigid to form a self-supporting element in the solar panel, but a surrounding frame construction of sheet metal continues to be required to hold the constituent elements of the panel together. Due to the rigid plastic foam element, it has been possible to make the sheet metal frame construction of smaller and thereby lighter dimensions, the weight of the solar panel effectively having been reduced compared with previous solar panels with stronger frame constructions and heavier insulation elements of mineral wool, for example. A problem with this solution, however, continues to be the relatively large number of constituent parts of the solar panel, which together with the relatively complicated sheet metal frame means that it will probably continue to be too expensive to manufacture so as to reach a sufficiently broad market to be able to justify large-scale series production. SUMMARY OF THE INVENTION: The aforementioned problems are solved in that the invention provides a solar panel comprising an absorber element, a heat-insulating insulation element placed between the absorber element and an underlayer, and a frame structure surrounding the insulation element and the absorber element. The invention is characterized in particular in that said insulation element and said frame structure are integratedly formed into an essentially box-shaped, self- supporting base element having a recess for accommodating said absorber element, which base element consists in the main of a foamed plastic material. In a preferred embodiment of the invention, the solar panel also comprises a transparent covering sheet placed over said absorber element. In an advantageous embodiment of the invention, the base element has fastening organs for the absorber element. The fastening organs consist of through holes in the base element, which holes are adapted to interact by press fit with pipe joints located on the absorber element. Furthermore, in a favourable embodiment, the base element has a support surface for contact with the covering sheet, which support surface is located on a continuous support vane which projects from the bottom surface of the recess on the base element. The recess in the base element preferably accommodates the absorber element in its entirety, including the pipe joints located on the absorber element. In an alternative embodiment, the base element is also clad with a surface layer of a plastic material, the density of which exceeds the density of said foamed plastic material. In a suitable embodiment, the base element has a recess for accommodating the transparent covering sheet, in which recess support surfaces facing upwards are executed for contact with the covering sheet. The foamed plastic material has a density in the range of 20-80 kg/m 3 , preferably 40-60 kg/m 3 , and also preferably consists of polypropylene foam. However, a range of other plastic foam materials can be used alternatively, such as polyethylene, polyurethane, polystyrene etc., which will be described in greater detail below. To sum up, the invention offers a very advantageous solar panel of a considerably lower weight than previously known solar panels. Due to the integrated base element in foamed plastic material, the number of constituent parts in the solar panel is also reduced, which together with the relatively low material cost of the plastic foam material signifies a considerably lower production cost. The low weight also makes it possible to fit the solar element smoothly on a house roof, for example, without the help of an expensive hoisting crane. BRIEF DESCRIPTION OF DRAWINGS: The invention will be described below in the form of embodiments with reference to the enclosed drawings, of which: Fig. 1 shows an exploded outline in perspective of a solar panel according to a first embodiment of the invention; Fig. 2 shows the solar panel in Fig. 1 , but in the assembled state; Fig. 3 shows a top view of the integrated base element in foamed plastic material; Fig. 4 shows a view in section of the long side of the base element, taken along the line B-B in Fig. 3; Fig. 5 shows a side view of one long side of the base element; Fig. 6 shows a view in section of the short side of the base element, taken along the line F-F in Fig. 5; Fig. 7 shows a view in section of the central part of the base element, taken along the line A-A in Fig. 3; Fig. 8 shows finally an alternative embodiment of the invention, in which the base element is clad with a surface layer of plastic material. DESCRIPTION OF THE EMBODIMENTS: In Fig. 1 , the reference number 1 generally describes a solar panel according to the invention. The solar panel 1 is constructed from an absorber element 2, a heat-insulating insulation element 3 placed between the absorber element 2 and an underlayer (not shown), and a frame structure 4 surrounding the insulation element 3 and absorber element 2. The frame structure 4 is formed integratedly according to the invention together with the insulation element 3 to give a box-shaped, self-supporting base element 5. Furthermore, the solar panel is sealed in the example shown by a transparent covering sheet 6, which is preferably manufactured from polycarbonate plastic. The base element 5 consists in its entirety in the example shown of a foamed plastic material with closed pores. The base element 5 is preferably executed in this connection in polypropylene foam with a density in the range of 20-80 kg/m 3 , preferably 40-60 kg/m 3 , with good heat-insulating properties. Other foamed plastic materials can also be used alternatively, however, such as polyethylene, polyurethane or polystyrene, for example. The foamed plastic material suitably also contains a UV stabilizer, such as carbon black, to protect against ultra-violet radiation. The fact that the frame structure 4 is formed integratedly with the insulation element 3 means that the frame structure 4 in itself acts as heat insulation, and thus does not need to be lined with separate insulating material, as is the case with many previously known solar panels. The integrated base element also has an essentially rectangular recess 7 to accommodate the absorber element 2. The absorber element 2 in the embodiment shown is of the type which is designed to be flowed through by a heat-bearing liquid, normally water or water with an anti-freeze admixture. Here the absorber element 2 according to the example shown comprises two absorber bodies 8, 9 arranged beside one another and incoming or outgoing pipe joints 10. The absorber bodies 8, 9 contain in a conventional manner a plurality of liquid channels (not shown). In an advantageous embodiment, the absorber bodies 8, 9 are executed in polypropylene plastic, but alternatively other plastic materials with similar properties can be used. In Fig. 2, the solar panel 1 according to the invention is shown in the assembled state, it being evident that the recess 7 in the base element 5 accommodates the absorber element 2 in its entirety, i.e. including the pipe joints 10, which on conventional solar panels (not shown) normally run outside the surrounding frame structure 4. An advantage is hereby achieved in group mounting of the finished solar panels 1 , for example on a house roof (not shown). It is also clear from Fig. 2 that a support surface 11 for contact with a covering sheet 2 is located on a continuous support vane 12 extending centrally over the base element 5, which vane projects from the bottom surface 13 of the recess 7 on the base element 5. In the embodiment shown, the two absorber bodies 8, 9 are placed on each side of this support vane 12. Together with further surrounding, upwardly facing support surfaces 14, 15 along a recess 16 in the frame structure 4 of the base element 5, the support surfaces on the support vane 12 offer good support for the transparent covering sheet 6. The extension of the support vane 12 is plainly evident from Fig. 3 and from the view in section in Fig. 7. The integratedly formed base element 5 also has fastening organs 17 for the absorber element 2, which consist of through holes 18 in the base element 5. The through holes 18 are adapted to interact by press fit with pipe joints 10 located on the absorber element 2. Following fitting, the absorber element 2 is hereby fixed without play in the base element 5. The extension of the holes 18 is plainly evident in Figs. 4, 5 and 6. The foamed plastic material in the elastic properties of the base element 5 is well-suited in the context for achieving a suitably "squeezing" press fit, which due to the properties of the plastic foam continues to give a certain flexibility in the case e.g. of bending stresses which arise on transportation or erection of the solar panel 1. Fig. 8 shows an alternative embodiment of the integratedly formed base element 5, in which the base element 5 is clad with a surface layer 19 of a plastic material, the density of which exceeds the density of said foamed plastic material. The plastic material in the surface layer 19 can consist here for example of polyethylene, polystyrene or any other plastic suitable for the purpose. The foamed plastic material can here be said to form a core 20 in the base element 5. The surface layer 19 gives the base element 5 increased protection against undesirable water penetration and other external damage. In the embodiment shown, the surface layer 19 is relatively thick, an advantageous production method consisting of rotation casting. The material in both the surface layer 19 and the core 20 consists suitably in this case of polyethylene. Alternatively, the surface layer 19 can be considerably thinner (not shown) and consist in practice of a thin, protective plastic film. The invention is not restricted to the embodiments in the above description and shown in the drawings, but can be varied freely within the scope of the following claims. For example, the solar panel 1 does not necessarily have to be flat as shown in the drawings, but an alternative embodiment can also consist of a curved solar panel 1 (not shown).

Claims: CLAIMS: 1. Solar panel (1 ) comprising an absorber element (2), a heat-insulating insulation element (3) placed between the absorber element (2) and an underlayer, and a frame structure (4) surrounding the insulation element (3) and the absorber element (2), characterized in that said insulation element (3) and said frame structure (4) are formed integratedly into an essentially box-shaped, self-supporting base element (5) having a recess (7) to accommodate said absorber element (2), which base element (5) consists in the main of a foamed plastic material. 2. Solar panel (1 ) according to Claim 1 , characterized in that the solar panel (1 ) also comprises a transparent covering sheet (6) placed over said absorber element (2). 3. Solar panel (1 ) according to Claim 1 or 2, characterized in that said base element (5) has fastening organs for the absorber element (2). 4. Solar panel (1 ) according to Claim 3, characterized in that said fastening organs (17) are through holes (18) in the base element (5), which holes (18) are adapted to interact by press fit with pipe joints (10) located on the absorber element (2). 5. Solar panel (1 ) according to Claims 2 to 4, characterized in that a support surface (11) for contact with the covering sheet (2) is located on a continuous support vane (12) which projects from the bottom surface (13) of the recess (7) on the base element (5). 6. Solar panel (1 ) according to any one or more of the preceding claims, characterized in that the recess (7) in the base element (5) accommodates the absorber element (2) in its entirety, including pipe joints (10) located on the absorber element (2). 7. Solar panel (1 ) according to any one or more of the preceding claims, characterized in that said base element (5) is clad with a surface layer (19) of a plastic material, the density of which exceeds the density of said foamed plastic material. 8. Solar panel (1 ) according to any one or more of the preceding claims, characterized in that said base element (5) has a recess (16) to accommodate the transparent covering sheet (6), in which recess (16) upwardly facing support surfaces (14, 15) are executed for contact with the covering sheet (6). 9. Solar panel (1 ) according to any one or more of the preceding claims, characterized in that said foamed plastic material has a density within the range 20-80 kg/m 3 , preferably 40-60 kg/m 3 . 10. Solar panel (1 ) according to Claim 8, characterized in that said foamed plastic material consists of polypropylene foam.

Inventors: CEDENBLAD BJOERN, CEDENBLAD, BJOERN
Applicants: CEDENBLAD BJOERN, UPONOR INNOVATION AB, CEDENBLAD, BJOERN
Application year: 2001
Main classification: F24J2
IPC codes: F24J2