Abstract:
A basic frame for a solar panel having a container for a liquid, which container is arranged to constitute a thermal solar panel that can be combined with a photovoltaic solar panel having a plurality of cells, wherein the frame is an extruded piece of predetermined length having at least one first channel arranged for inletting a liquid and one second channel arranged for outletting the liquid. The invention also relates to a hybrid solar panel including the basic frame and to a method of manufacturing the solar panel.

Description:
TECHNICAL FIELD 
       [0001]    The present invention generally relates to a solar panel structure and to the solar panel obtained by using the structure. 
         [0002]    More particularly the present invention relates to a basic frame configured for supporting a photovoltaic solar panel (photovoltaic panel) and forming a thermal solar panel (thermal panel) coupled with the photovoltaic panel. 
       PRIOR ART 
       [0003]    Panels arranged to convert solar radiation into thermal energy (thermal panels) and electric energy (photovoltaic panels) are well known. In particular, hybrid solar panels (hybrid panels) are known, in which a thermal panel is coupled with a photovoltaic panel. 
         [0004]    For instance, publication US — 2004/0025931_A1, in the name of the applicant, discloses a hybrid panel in which a photovoltaic panel comprising a plurality of photovoltaic cells and arranged to be directly exposed to solar radiation is coupled, by means of a heat conducting plate, to a container configured for containing water or a similar liquid and forming, in association with the conducting plate, the thermal panel. 
         [0005]    The prior art thermal panel is made up of the conducting plate and the container, both made of steel, and internally includes a plurality of partitioning elements, preferably made of steel, arranged to create a preferential path for water used to accumulate thermal energy. 
         [0006]    In accordance with such a prior art, the plate and the container are welded or glued at the respective edges, and the partitioning elements are fastened to the plate and the container in equivalent manner. 
         [0007]    The Applicant, while realising that the prior art hybrid panel allows improving the overall efficiency of the photovoltaic panel, has detected some limits and problems making the manufacture of such kind of panel difficult and expensive. 
         [0008]    First, the Applicant has realised that, since the thermal panel is subjected to internal pressures of at least 2 or 3 bars, fastening the different components (plate, container, partitioning elements) is particularly critical and hence such as to entail high manufacturing times and costs. 
         [0009]    The Applicant has further realised that, in use, the thermal panel, and especially the plate and the container, undergo deformations due to the water pressure, which deformations may consequently cause, in some cases, irreparable failures in the cells of the photovoltaic panel. 
         [0010]    The Applicant has moreover realised that the prior art panel, in case of different power requirements, must be manufactured with sizes that are different for the different cases in order to cope with the respective market demands, and thus it is scarcely flexible. 
         [0011]    In summary, the Applicant has realised that the prior art hybrid panels manufactured in manners similar to those described above suffer from the problems, mutually related, of high manufacturing difficulty, risk of failures and scarce flexibility. 
       DESCRIPTION OF THE INVENTION 
       [0012]    It is an object of the present invention to solve the problems of the prior art. 
         [0013]    The object is achieved by the solar panel structure as claimed herein. 
         [0014]    The present invention also concerns a solar panel having the structure according to the invention. 
         [0015]    The claims are integral part of the technical teaching provided herein in respect of the invention. 
         [0016]    In accordance with a feature of a preferred embodiment of the present invention, the basic frame for a solar panel is obtained by an extrusion process and constitutes a thermal solar panel that can be associated with a photovoltaic solar panel in order to form a hybrid solar panel. 
         [0017]    In accordance with another feature of the present invention, the basic frame includes at least one inlet channel and one outlet channel for a cooling liquid used in the thermal solar panel. 
         [0018]    In accordance with a further feature of the present invention, the hybrid solar panel obtained by means of the basic frame according to the invention constitutes a modular panel that can be connected side by side with further modular panels through coupling means that are formed in or can be applied to the basic frame itself. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0019]    The above and other features and advantages of the present invention will become apparent from the following description of preferred embodiments, made by way of non limiting example with reference to the accompanying drawings, in which elements identified by a same or similar numerical reference denote elements having the same or similar function and construction, and in which: 
           [0020]      FIG. 1   a  is an overall view, conventionally in front perspective, of a detail of a hybrid panel made in accordance with a first embodiment of the present invention; 
           [0021]      FIG. 1   b  is an overall view, conventionally in front perspective, of a detail of a hybrid panel made in accordance with a second embodiment of the present invention; 
           [0022]      FIG. 2   a  is a cross-sectional view of a pair of structural members to be used for making hybrid panels in accordance with the first embodiment of the present invention, where some constructional details are highlighted; 
           [0023]      FIG. 2   b  is a cross-sectional view of a pair of structural members to be used for making hybrid panels in accordance with the second embodiment of the present invention, where some constructional details are highlighted; 
           [0024]      FIG. 3  is a view, conventionally in rear perspective, of constructional members associated with the hybrid panel according to the invention; 
           [0025]      FIG. 4  schematically shows the behaviour of the liquid flow inside the hybrid panel; and 
           [0026]      FIG. 5  shows an exemplary embodiment of electrical connections for the hybrid panel according to the invention. 
       
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT 
       [0027]    Referring to  FIG. 1   a  or  1   b , a solar panel  10  according to the present invention, for instance a hybrid solar panel, comprises one or more modules  12  ( FIGS. 1   a ,  1   b ,  2   a ,  2   b ) of predetermined length. 
         [0028]    Each module  12 , in the different embodiments, includes a basic frame  21 , a photovoltaic panel  41  having a plurality of cells  42 , a protective component or panel  43  and, preferably, one or more thermally insulating components or panels  45 . 
         [0029]    Photovoltaic panel  41 , as it will be disclosed in detail below, is fastened to a first face, or upper face,  25   a  of basic frame  21 . 
         [0030]    Thermally insulating panel(s)  45 , for instance in accordance with a first embodiment shown in  FIGS. 1   a  and  2   a , is (are) fastened in known manner to a second face, or lower face,  26   a  of basic frame  21 . 
         [0031]    In accordance with a second embodiment shown in  FIGS. 1   b  and  2   b , basic frame  21  includes, on opposite longitudinal edges  31  and  32 , respective retaining fins  35   a  and  35   b , for instance shaped as an inverted T, configured for receiving thermally insulating panel(s)  45 . 
         [0032]    In the different embodiments, basic frame  21  is arranged to form both a bearing structure and a modular thermal panel. Preferably, basic frame or thermal panel  21  is made of aluminium alloy, for instance a 6060 alloy resisting to high temperatures, and is obtained by an extrusion process whereby it does not require any welding between possible components of thermal panel  21  itself. 
         [0033]    Of course, in accordance with further embodiments, basic frame  21  can be obtained by an extrusion process from other materials, e.g. plastic materials with high thermal and mechanical resistance, without thereby departing from the scope of what described and claimed. 
         [0034]    Basic frame or thermal panel  21  ( FIGS. 1   a ,  1   b ,  2   a ,  2   b ,  3 ,  4 ) includes a first channel  23 , for instance for inletting a liquid such as water, to which reference is made hereinafter for easiness of description, and a second channel  24 , for instance for water outlet. Channels  23  and  24  have first and second open ends  27   a  and  27   b , respectively, are located between two walls  25  and  26 , here conventionally referred to as upper wall  25  and lower wall  26 , and form a modular container for a liquid for thermal panel  21 . 
         [0035]    In accordance with the described embodiments, channels  23  and  24  have a predetermined height “h” and width “1”, and width “1” is much greater than height “h”. 
         [0036]    For instance, height “h” may be in the range 5 to 7 mm, so that it allows reducing, in use, the overall weight of panel  10 . Actually, as it can be readily understood, a reduction in height “h” results in a reduction of the volume of water circulating in the panel and hence in a reduction of the weight of the same panel when in use. 
         [0037]    Therefore, reduction in height “h” is convenient to solve possible problems deriving from structural limits associated with panel positioning. 
         [0038]    In the different embodiments, the first channel (inlet channel)  23  and the second channel (outlet channel)  24  are divided into two or three portions, of substantially the same or similar sizes, separated by respective columns  23   a  and  24   a . Such configurations, which are deemed preferable, allow making basic frame  21  more rigid and less subject to deformations in case of compression stresses exerted, in use, by the water (e.g. 3-4 bars), in the exemplary case in which width “l” is much greater than height “h”. 
         [0039]    Of course, in accordance with other embodiments, more than one or two columns can be provided, or the columns can be lacking, depending on the pressure envisaged, in use, in hybrid panel  10 . 
         [0040]    Moreover, basic frame  21  of each module  12  is configured so as to house in optimised manner photovoltaic panel  41  and protective component  43 . 
         [0041]    More particularly, basic frame  21  includes, on two opposite sides  31  and  32 , conventionally referred to as first and second side edges, respectively, first and second C-shaped profiles  31   a  and  32   a , respectively, which preferably are mutually specular and are configured for receiving photovoltaic cells  42  in an area adjacent to outer or upper face  25   a  and preferably separated from that face by a sheet  28 , e.g. an electrically insulating but thermally conducting sheet, or a layer  28  with similar characteristics, of known type. 
         [0042]    More preferably, an insulating layer  41   b , e.g. a layer of EVA (Ethyl Vinyl Acetate), arranged to electrically insulate cells  42  from insulating sheet  28 , is also interposed between insulating sheet  28  and cells  42 . 
         [0043]    In the alternative, in accordance with other embodiments, a transparent resin can be interposed between photovoltaic cells  42  and insulating sheet  28 , as disclosed in patent publication WO2008/0044250 in the name of the Applicant. 
         [0044]    Opposite edges  31  and  32  further include, besides C-shaped profiles and farther away from upper face  25   a  of basic frame  21 , first and second L-shaped profiles  31   b  and  32   b , respectively, arranged to receive protective component  43 , for instance a glass pane, arranged to protect cells  42  of photovoltaic panel  41  for instance from atmospheric agents. 
         [0045]    Preferably, an insulating layer  41   a , e.g. a layer of EVA (Ethyl Vinyl Acetate) arranged to electrically insulate cells  42  from protective component  43 , is interposed between protective component  43  and cells  42 . 
         [0046]    In the alternative, in accordance with other embodiments, a transparent resin can be interposed between protective component  43  and photovoltaic cells  42 , as disclosed in patent publication WO2008/0044250_A1 in the name of the Applicant. 
         [0047]    Preferably, one of the L-shaped profiles, e.g. the second L-shaped profile  32   b , is extended, in a direction away from upper face  25   a , by a hook-shaped element  32   c  shaped so as to protect cells  42  of photovoltaic panel  41  from possible seepage of water at the edges of protective component  43 . 
         [0048]    In accordance with a first embodiment of the present invention, side edges  31  and  32 , respectively, further include coupling means  33  and  34 , preferably located at a lateral position and externally of channels  23  and  24  and configured so as to mutually cooperate and to allow coupling panels  10  side by side. 
         [0049]    For instance, coupling means  33  and  34  have a dovetail shape, female and male respectively, and are arranged to enable a longitudinal insertion of two basic frames into each other, as it can be readily understood by the skilled in the art, so as to allow building hybrid panels  10  with multiple modules  12  of predetermined length. 
         [0050]    Basic frame  21  further includes, in correspondence of external or lower face  26   a  of lower wall  26 , one or more seats or guides  36 , for instance two seats, longitudinally arranged relative to basic frame  21  and arranged to house fastening means, for instance screw heads, at any position along the basic frame. 
         [0051]    Thanks to such a configuration of the first embodiment, the screws allow fastening hybrid panel  10  to coupling bars or points external to the panel, the position of which is thus constrained in a single direction, as it can be readily understood by the skilled in the art. 
         [0052]    In accordance with a second embodiment of the present invention, which is deemed preferable, side edges  31  and  32 , respectively, are substantially flat, so that they can face each other. 
         [0053]    Preferably, in such an embodiment, opposite fins  36   a  and  36   b , respectively, extending over the whole length of basic frame  21 , are provided in correspondence of retaining fins  35   a  and  35   b.    
         [0054]    Opposite or coupling fins  36   a  or  36   b  preferably allow achieving two objects:
       a first object is, for instance, to allow coupling together, by means of removable coupling elements  46 , for instance suitable pegs, hooks or clips, basic frames  21  of panels  10 , so as to allow building hybrid panels  10  with multiple modules  12 , for instance having a predetermined length and a width determined by the number of modules arranged side by side;   a second object is, for instance, making coupling fins  36   a  or  36   b  cooperate with retaining fins  35   a  and  35   b , respectively, in order to form, near side edges  31  and  32 , the seats or guides  36  arranged to house the fastening means, for instance screw heads, at any position along basic frame  21 , of course except the points where pegs  46 , if any, are provided.       
 
         [0057]    As far as photovoltaic panel  41  is concerned, cells  42  are connected in series on each thermal panel  21 , in known manner, so that connection terminals  42   a  and  42   b , respectively, with opposite polarities are provided at the ends of inlet channel  23  and outlet channel  24 . 
         [0058]    For instance, in the illustrated embodiment, the cells are arranged so that connection terminals  77   a  and  77   b  ( FIG. 5 ), respectively, with opposite polarities are provided at the second ends  27   b.    
         [0059]    Preferably, the terminals are connected together by means of a hold or protective circuit  49 , for instance a hold diode, known per se. 
         [0060]    Preferably, the number of serially connected cells is 2 to 24, for instance in case of cells of known type having a size of 156×156 mm. 
         [0061]    Hybrid panel  10  also comprises, preferably at both ends  27   a  and  27   b  ( FIGS. 1   a ,  1   b ,  2   a ,  2   b ,  3 ,  4 ) of basic frame  21 , a plurality of holes  37  for receiving screws  67 , for instance self-threading screws. 
         [0062]    Holes  37  are so arranged as to allow fastening first and second caps  39   a  and  39   b , respectively, to the respective ends  27   a  and  27   b  of the basic frame, in order to enable completion of the manufacture of hybrid panel  10 . 
         [0063]    More particularly, the first cap  39   a , in accordance with the present exemplary embodiment, is arranged to convey inflowing water towards inlet channel  23  and to convey water flowing out from outlet channel  24 , for instance towards another module  12 . 
         [0064]    In accordance with a first embodiment shown in  FIG. 1   a , the first cap  39   a  is associated with an inlet hydraulic connector  59   a  and an outlet hydraulic connector  59   b  and it includes first and second cavities  53  and  54 , respectively, not communicating with each other. The first cavity, or water inlet cavity  53 , is arranged to convey water into inlet channel  23  and the second cavity  54  is arranged to convey water flowing out from outlet channel  24 . 
         [0065]    In accordance with a second embodiment shown in  FIG. 1   b , inlet and outlet hydraulic connectors  59   a  and  59   b  are included or formed in cap  39   a.    
         [0066]    Such a configuration, which is deemed preferable, allows making the hydraulic seal of the connectors safer and panel  10  more compact. 
         [0067]    Preferably, the first cap is associated with one or more gaskets  38   a , for instance one or more sealing gaskets made of silicone, arranged to ensure tightness of cap  39   a  by cooperating with screws  67 . 
         [0068]    In accordance with other embodiments, the gaskets could be replaced by a sealing material arranged to ensure tightness of the cap by cooperating with screws  67 . 
         [0069]    Gasket(s)  38   a  preferably has (have) one or more holes in correspondence with each cavity  53  and  54 , respectively. 
         [0070]    The holes, for instance two pairs of holes  53   a ,  53   b  and  54   a ,  54   b , as illustrated in the first embodiment described herein, are arranged to make inlet water flow into the one or more portions into which inlet channel  23  is divided, and to make outlet water flow out from the one or more portions into which outlet channel  24  is divided. 
         [0071]    More preferably, holes  53   a  and  54   a  have a smaller size than holes  53   b  and  54   b  in order to compensate, in use, possible pressure drops of the fluid inside cavities  53  and  54 , respectively. 
         [0072]    The second cap  39   b  includes, for instance, a first component  39   b   1 , arranged to convey water from inlet channel  23  to outlet channel  24 , a second component  39   b   2 , arranged to take part in the electrical connection of cells  42  to connection terminals  42   a  and  42   b , in order to supply with electric energy electrical devices, if any, connected to photovoltaic panel  41 , and a third component  39   b   3 , arranged to electrically insulate plate  48  and protective diode  49  from external agents and to seal panel  10  at the second end  27   b.    
         [0073]    In particular, in accordance with the different embodiments described herein, the first component  39   b   1  of cap  39   b  has a cavity  55  arranged to convey water from inlet channel  23  to outlet channel  24  of thermal panel  21 . 
         [0074]    Preferably, the first component  39   b   1  or cap  39   b  itself is associated with one or more gaskets  38   b , for instance sealing gaskets made of silicone, arranged to ensure tightness of the first component  39   b   1  or of cap  39   b  by cooperating with screws  67 . 
         [0075]    In accordance with other embodiments, the gaskets could be replaced by a sealing material arranged to ensure tightness of cap  39   b  by cooperating with screws  67 . 
         [0076]    The second component  39   b   2  of cap  39   b  ( FIG. 5 ) preferably includes a printed circuit board (circuit) with connection tracks and protective diode  49 . 
         [0077]    More preferably, circuit  48  has through-holes  48   a , suitably electrically insulated and arranged to allow connecting terminals  77   a  and  77   b  of cells  42  to circuit  48 , e.g. by bending terminals  77   a  and  77   b  and welding them to circuit  48 . 
         [0078]    The third component  39   b   3  of cap  39   b , in the preferred embodiment of the invention, is to provide the overall protection of hybrid panel  10  at the second end  27   b  thereof. 
         [0079]    Advantageously, in the preferred embodiment, the structure of second cap  39   b , as illustrated herein, allows containing outside each module  12  both the hydraulic circuitry for connection between channels  23  and  24 , and the electrical circuitry for connection among cells  42 , thereby making maintenance of each module easier. 
         [0080]    Of course, in accordance with other embodiments, the first and second caps may include the described components with a different arrangement, or they can be differently arranged, without thereby departing from the scope of what described and claimed. 
         [0081]    The manufacture of a hybrid panel  10  in accordance with the present invention includes one or more of the following steps:
       obtaining by an extrusion process one or more basic frames  21  of predetermined length, e.g. 6.5 m;   cutting basic frames  21  to the desired size, if necessary, depending on the kind of hybrid panel  10  to be manufactured, for instance depending on the number of photovoltaic cells to be installed, the solar power to be converted, and so on;   placing cells  42  on upper face  25   a  after having applied, for instance, layer  28  of an electrically insulating but thermally conducting material; such a step can be integrated with the deposition of an EVA layer;   placing protective panel  43 , made for instance of glass, by exploiting L-shaped profiles  31   b  and  32   b  of the basic frame; such a step can be integrated with the deposition of an EVA layer;   applying thermally insulating panel(s)  45  to lower face  46   a  of basic frame  21 , for instance by exploiting retaining fins  35   a  and  35   b;      possibly arranging several basic frames  21  side by side, by exploiting, in accordance with the first embodiment, coupling means  33  and  34  of basic frame  21 , or, in the alternative, in accordance with the second embodiment, by applying pegs  46 , thereby forming hybrid panels  10  with multiple modules  12 ;   securing caps  39   a  and  39   b  having respective ducts and electric terminals to the panel.       
 
         [0089]    Panel  10  manufactured in this manner has, thanks to basic frame  21 , a self-supporting structure, which is easy to be handled and secured, for instance, to roofs or building structures. 
         [0090]    In particular panel  10 , thanks to the provision of guides  36 , can be placed in flexible and handy manner on building roofs. 
         [0091]    The panel, when associated with thermally insulating panels  45  applied on lower face  26   a  of basic frame  21 , can also form building roofings. 
         [0092]    Panel  10 , having a basic frame or thermal panel  21  obtained by an extrusion process, is particularly rigid and thus such that it can prevent damages to cells  42  secured to the upper face of the basic frame. 
         [0093]    The provision of caps  39   a  and  39   b  allows tightly sealing the panels and hydraulically connecting multiple modules. 
         [0094]    More particularly, cap  39   b  also allows bringing protective circuit  49  outside the photovoltaic panel, allowing maintenance of the circuit without need to remove the photovoltaic panel. 
         [0095]    Hybrid panels  10  as described may have a length and comprise a number of modules arranged side by side substantially depending only on the kind of installation to be made, in terms of surface to be covered and power to be delivered. 
         [0096]    Hybrid panels  10  according to the invention are modular panels and are easy to be manufactured, in that they have a constant shape, possibly with variable length, so that standardised equipment can be used for their manufacture. 
         [0097]    Moreover, in case of a failure in a panel with several modules  12 , the constructional modularity allows replacing the failed module only, without need to replace the whole panel. 
         [0098]    Such a feature makes it possible to provide kits of panels of standardised length, to be sold for performing a modular maintenance on the assembled panels. 
         [0099]    Of course, obvious changes and/or modifications can be made in the above description in respect of the size, the shape, the components, the circuit elements and the connections, as well as in respect of the details of the illustrated construction and the manufacturing method, without departing from the scope of the invention as set forth in the following claims.