Patent Publication Number: US-2023144923-A1

Title: Photovoltaic converter

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Patent Application is a national stage application, filed under 35 U.S.C. § 371, of International Patent Application No. PCT/IB2021/052616 filed on Mar. 30, 2021, that claims priority from Italian Patent Application No. 102020000006622 filed on Mar. 30, 2020, the entire disclosure of each which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     The present invention relates to a photovoltaic converter, in particular for electric power generating panels based on luminescent solar concentrators. The invention may be advantageously applied, though non-exclusively, for making architectural elements for the civil and industrial construction business, such as windows, glass walls, roofing elements for greenhouses. 
     2. Description of Related Art 
     As known, generating panels of this type are systems comprising a luminescent solar concentrator (LSC) and a photovoltaic converter. The luminescent solar concentrator is in the form of a slab made of a material semitransparent to the solar radiation (from the infra-red to the ultraviolet), containing colour centres and selectively absorbing a portion of the solar spectrum. The absorbed luminous radiation may be re-emitted in a substantially isotropic manner from the colour centres as a fluorescence radiation and is partially conveyed towards the perimeter of the slab as a result of the total inner reflection (namely, the slab serves as a waveguide). The photovoltaic converter comprises a plurality of photovoltaic-cell devices arranged along at least a part of the perimeter of the slab and connected between each other according to the design preferences. The fluorescence radiation conveyed towards the perimeter of the luminescent solar concentrator is collected by the photovoltaic cells and converted into electricity, in particular into a current proportional to the incident optical power. As mentioned, photovoltaic-cell devices may be connected between each other (in series or in parallel) depending on the design preferences, i.e. depending on the voltages and/or currents intended to be supplied. 
     A drawback of the known solutions is represented by lack of flexibility in assembling. In the known photovoltaic converters, the photovoltaic-cell devices are welded on substrates and are coupled along the perimeter of the luminescent solar concentrator directly or by layers serving as impedance adapters. Connections between the cells are made on the spot by welding operations, which are time-consuming and require highly skilled operators. There is therefore the likelihood of assembly mistakes by poorly skilled operators or not enough used to specific electric and/or electronic working operations. 
     In some solutions, tailor-made components with a plurality of photovoltaic cells fixed on a same support are pre-assembled and applied on the slabs. Such type of solutions need in any case be designed singularly and are not likely to be produced on a large-scale basis. For instance, in the field of the photovoltaic systems for architectural integration, the lack of dimensional standards does not allow to identify a type of photovoltaic-cell device capable of fulfilling all the installation needs. The lack of flexibility thus affects the costs and the complexity of either production processes and of managing a necessarily very wide range of products, however with relatively inefficient scale economies. 
     SUMMARY OF THE DISCLOSURE 
     It is an aim of the present invention to provide a photovoltaic converter able to overcome or at least alleviate the disclosed limitations. 
     According to the present invention there is therefore provided a photovoltaic converter for electric power generating panels comprising: 
     a plurality of photovoltaic modules, each comprising a substrate, extending along a main direction from a first end to a second end, and a plurality of photovoltaic devices, arranged on the substrate in succession along the main direction; and 
     at least a bridge module insertion-connecting a respective upstream photovoltaic module and a respective downstream photovoltaic module. 
     The modular creation of the photovoltaic converter by insertion-connected bridge modules has several advantages. Firstly, the insertion-connection, with no welding required, simplifies the assembly operation and prevents defects and malfunctions from occurring in case welds are not properly made. Furthermore, it is possible to manufacture identical modules and assemble them according to the design preferences to obtain the desired characteristics in relation to the maximum voltage and current supplied by the photovoltaic converter. The use of a single type of photovoltaic module in various combinations makes it possible to advantageously reduce costs both for bigger production scale economies, and for simplifying the warehouse management, which must have a small number of components. 
     According to an aspect of the invention, the photovoltaic modules are arranged in succession and are aligned in a longitudinal direction, according to the respective main directions. 
     According to an aspect of the invention, each photovoltaic module comprises an anode connector at the first end of the substrate and a cathode connector at the second end of the substrate and wherein the bridge module is configured to couple to the cathode connector of the respective upstream photovoltaic module and to the anode connector of the respective downstream photovoltaic module. 
     According to an aspect of the invention, in each photovoltaic module, the anode connector comprises a module anode terminal and the cathode connector comprises a module cathode terminal and the photovoltaic devices are connected in series between the module anode terminal and the module cathode terminal. 
     According to an aspect of the invention, in each photovoltaic module, the anode connector comprises a first line terminal and a second line terminal and the cathode connector comprises a third line terminal and a fourth line terminal, and wherein each photovoltaic module comprises a first conductive line, extending on the substrate between the first line terminal and the third line terminal, and a second conductive line, extending on the substrate between the second line terminal and the fourth line terminal. 
     The structure of the photovoltaic modules makes it possible to connect them in different configurations, also thanks to the fact that the first connection lines and the second connection lines of distinct photovoltaic modules may be easily connected to form lines that are common to the whole photovoltaic converter or to at least a whole string of photovoltaic modules. 
     According to an aspect of the invention, the bridge module comprises one first bridge connector and one second bridge connector, each having a respective first bridge terminal, a respective second bridge terminal and a respective third bridge terminal; and wherein the first bridge terminal, the second bridge terminal and the third bridge terminal of the first bridge connector are respectively connected to the first line terminal, second line terminal and module cathode terminal of the upstream photovoltaic module and the first bridge terminal, the second bridge terminal and the third bridge terminal of the second bridge connector are respectively connected to the third line terminal, fourth line terminal an module anode terminal of the downstream photovoltaic module. 
     The structure of the bridge module makes it possible to immediately connect two photovoltaic modules without any further components, making the photovoltaic converter assembly easier. 
     According to an aspect of the invention, the first bridge terminal and the second bridge terminal of the first bridge connector are respectively connected to the first bridge terminal and to the second bridge terminal of the second bridge connector. 
     Thereby, the bridge module connects the first connection lines and the second connection lines of distinct photovoltaic modules to form lines that are common to the entire photovoltaic converter. 
     According to an aspect of the invention, the converter comprises a plurality of bridge modules each connecting a respective upstream photovoltaic module and a respective downstream photovoltaic module. 
     Advantageously, the photovoltaic modules may be combined flexibly and in the desired number simply using a proper amount of bridge modules. 
     According to an aspect of the invention, the bridge modules comprise at least a series bridge module, connecting the respective upstream photovoltaic module and the respective downstream photovoltaic module with a series-type connection. 
     According to an aspect of the invention, in the series bridge module the third bridge terminal of the first bridge connector is connected to the third bridge terminal of the second bridge connector. 
     According to an aspect of the invention, the bridge modules comprise at least a parallel bridge module, connecting the respective upstream photovoltaic module and the respective downstream photovoltaic module with a parallel-type connection. 
     According to an aspect of the invention, in the parallel bridge module, in the first bridge connector the third bridge terminal is connected to the first bridge terminal and in the second bridge connector the third bridge terminal is connected to the second bridge terminal. 
     The series-type and parallel-type bridge modules are sufficient to combine the photovoltaic modules in any desired configuration. In particular, the photovoltaic modules of a same string may be connected in series-parallel combinations, all of them in series or in parallel or between the first conductive line and the second conductive line. In the series-parallel configurations, consecutive photovoltaic modules are connected to groups in series by series bridge modules. Furthermore, the groups of photovoltaic modules in series are connected in parallel between the first conductive line and the second conductive line by parallel bridge modules connected at the beginning and the finishing of each group. The groups may contain an arbitrary number of photovoltaic modules. The number of photovoltaic modules in each group and the number of groups of photovoltaic modules may be selected to determine the maximum voltage and the maximum current that the photovoltaic converter is able to supply. Only two types of components thus enable a very bight flexibility, to the benefit of the reduction in production costs and management. 
     According to an aspect of the invention, the converter comprises: 
     at least a string defined by a plurality of photovoltaic modules consecutively arranged and connected through at least one of the bridge modules; 
     a string beginning module, connected to the photovoltaic module at a beginning end of the string and having a first distribution connector and a string beginning connector; and 
     a string finishing module, connected to the photovoltaic module at a finishing end of the string and having a second distribution connector and a string finishing connector. 
     String beginning and finishing modules couple to the photovoltaic modules exactly as bridge modules, to the benefit of ease of assembly. 
     According to an aspect of the invention, the photovoltaic modules comprise a protection device in parallel to at least one of the photovoltaic devices. 
     The expedient allows the functioning of the photovoltaic converter also in case of breakdown of the single photovoltaic module and improves the performance in situations of partial shading. 
     According to the present invention, there is also provided an electric power generating panel, comprising: 
     a luminescent solar concentrator having a first face, a second face and a perimeter side around the first face and the second face; 
     a photovoltaic converter as mentioned above applied to at least a portion of the perimeter side of the luminescent solar concentrator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the invention, some embodiments thereof will now be disclosed, for merely illustrative and non-limiting purposes and with reference to the enclosed drawings, wherein: 
         FIG.  1    is a perspective view of a solar concentrator comprising a photovoltaic converter; 
         FIG.  2    is a simplified schematic view of a photovoltaic converter string of  FIG.  1    in accordance with an embodiment of the present invention; 
         FIG.  3    is an enlarged plan view from above of a first component of the photovoltaic converter of  FIG.  1   ; 
         FIG.  4    is an enlarged plan view from above of a variant of the first component of the photovoltaic converter of  FIG.  1   ; 
         FIG.  5    is an enlarged plan view from below of a second component of the photovoltaic converter of  FIG.  1   ; 
         FIG.  6    is an enlarged plan view from below of a third component of the photovoltaic converter of  FIG.  1   ; 
         FIG.  7    is an enlarged plan view from below of two samples of the first component and second component of the photovoltaic converter of  FIG.  1   , during the assembly step; 
         FIG.  8    is a side view of two samples of the first component and second component of the photovoltaic converter of  FIG.  1    been assembled; 
         FIG.  9    is a side view of two samples of a further variant of the first component and second component of the photovoltaic converter of  FIG.  1    being been assembled; 
         FIG.  10    is an enlarged plan view from below of a fourth component of the photovoltaic converter of  FIG.  1   ; 
         FIG.  11    is an enlarged plan view from below of a fifth component of the photovoltaic converter of  FIG.  1   ; 
         FIG.  12    is a simplified schematic view of a photovoltaic converter string of  FIG.  1    in accordance with a different embodiment of the present invention; 
         FIG.  13    is a simplified schematic view of a photovoltaic converter string of  FIG.  1    in accordance with a further embodiment of the present invention; 
         FIG.  14    is an equivalent circuit diagram of the string of  FIG.  2   ; 
         FIG.  15    is an equivalent circuit diagram of the string of  FIG.  12   ; and 
         FIG.  16    is an equivalent circuit diagram of the string of  FIG.  13   . 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     With reference to  FIG.  1   , an electric power generating panel is indicated as a whole by reference number  1  denotes and comprises a luminescent solar concentrator  2  and a photovoltaic converter  3  made according to an embodiment of the present invention. The luminescent solar concentrator  2  is in the form of a slab comprising a matrix made of a material that is transparent or semitransparent to the concerned radiations (such as transparent glass or a transparent polymer material), and one or more photo-luminescent compounds generally selected, for instance, from organic compounds, metal complexes, inorganic compounds (such as, rare-earth elements), quantum dots (QDs). The luminescent solar concentrator  2  has for instance square or rectangular shape, with sides non-limitedly ranging from 50 cm to 100 cm, and has a first face  2   a,  a second face  2   b  and perimetral (or lateral) side  2   c  around the first face  2   a  and the second face  2   b.    
     The photovoltaic converter  3  is attached to a portion of the perimeter side of the luminescent solar concentrator  2 , for instance two longer sides, so as to receive the luminescence radiation conveyed through the luminescent solar concentrator  2  by total reflection between the first face  2   a  and the second face  2   b  until the perimeter side  2   c.  The photovoltaic converter  3  may be for instance glued, possibly with an interposed optic impedance adapter layer, not shown. 
     The photovoltaic converter  3  comprises a plurality of photovoltaic modules  5 , which are aligned and arranged in succession along the perimeter side  2   c  of the luminescent solar concentrator  2 . Even though the photovoltaic converter  3  may include even only two photovoltaic modules  5 , there is advantageously a higher number thereof. Groups of consecutive photovoltaic modules  5  connected between each other are organised in one or more strings  6 , for instance one for each side greater than the perimeter side  2   c.    
       FIG.  2    shows an example of one of the strings  6  of the photovoltaic converter  3 . In addition to photovoltaic modules  5 , the string  6  comprises a string beginning module  7 , a string finishing module  8  and a plurality of bridge modules, which include series bridge modules  10  and parallel bridge modules  11 . 
     The string beginning module  7  is connected to a distribution line  12  and is coupled to one of the photovoltaic modules  5  arranged at a beginning end of the string  6 . The string finishing module  8  is connected to a distribution line  12  and is coupled to one of the photovoltaic modules  5  arranged at a finishing end of the string  6 . The distribution line  12  is used to convey the current generated by the photovoltaic modules  5  towards users and/or a power grid distribution network. 
     Each of the series bridge modules  10  and parallel bridge modules  11  connects between each other a respective upstream photovoltaic module  5  (relative to the direction from the string beginning to the string finishing) and a respective downstream photovoltaic module  5 . 
       FIG.  3    shows one of the photovoltaic modules  5 , which will be hereinafter referred to considering that all the photovoltaic modules  5  of the photovoltaic converter  3  have identical structure. The photovoltaic module  5  comprises a substrate  14  extending along a main direction D from a first end to a second end, and a plurality of photovoltaic devices  15 , housed on the substrate  14  in succession along the main direction D. The photovoltaic modules  5  of the string  6  are aligned in a longitudinal direction according to the respective main directions D, that are common. For instance, the substrate  14  may be a printed circuit board and the photovoltaic modules  15  may be photovoltaic cells. For merely exemplary and non-limiting purposes, a photovoltaic module  5  may be for instance 25 cm long and its photovoltaic devices  15  may generate as a whole a maximum voltage of 14 V. 
     Furthermore, the photovoltaic module  5  comprises an anode connector  17  and a cathode connector  18  respectively at the first end and at the second end of the substrate  14 . The anode connector  17  comprises a first line terminal  17   a,  a second line terminal  17   b  and a module anode terminal  17   c.  The cathode connector  18  comprises a third line terminal  18   a,  a fourth line terminal  18   b  and a module cathode terminal  18   c.    
     A first conductive line  20  and a second conductive line  21  extend on the substrate  14  respectively between the first line terminal  17   a  and the third line terminal  18   a  and between the second line terminal  17   b  and the fourth line terminal  18   b.    
     The photovoltaic devices  15  are connected in series between the module anode terminal  17   c  and the module cathode terminal  18   c.  Conductive lines  20 ,  21  extend in parallel to the succession of the photovoltaic devices  15  on opposite sides thereof, as in  FIG.  3   , or adjacent one another, as in  FIG.  4   . Conductive lines  20 ,  21  may consist also of several conductive layers within the substrate  14  (if the substrate is multilayer) and the connections between terminals and devices may be made by pass-through metallisation or vertical contacts. 
     Protection devices  19 , such as diodes or thyristors, may be connected in parallel to devices  15 , to allow the functioning of the photovoltaic converter  3  even in case of breakdown of the single photovoltaic module  5  or in case of total or partial shading of the photovoltaic module  5  or of the string  6 . Each photovoltaic module  5  may comprise a plurality of protection devices  19 , each protection device  19  may be connected in parallel to different groups of photovoltaic devices  15 . 
     The anode connector  17  and the cathode connector  18  are insertion- or interlock-type connectors, in this case of female-type. 
     One of the series bridge modules  10 , all identical between each other, is shown in  FIG.  5   . The series bridge module  10  comprises a substrate  22 , for instance a printed circuit board, a first bridge connector  23  and a second bridge connector  24 , having each a respective first bridge terminal  23   a,    24   a,  a respective second bridge terminal  23   b,    24   b  and a respective third bridge terminal  23   c,    24   c.  The homologous terminals of the first bridge connector  23  and of the second bridge connector  24  are directly connected between each other. Therefore the first bridge terminal  23   a,  the second bridge terminal  23   b  and the third bridge terminal  23   c  of the first bridge connector  23  are directly connected respectively to the first bridge terminal  24   a,  second bridge terminal  24   b,  third bridge terminal  24   c  of the second bridge connector  24 . Furthermore, the first bridge connector  23  and the second bridge connector  24  are configured to connect respectively to the cathode connector  18  of the upstream photovoltaic module  5  and to the anode connector  17  of the downstream photovoltaic module  5 . Each series bridge module  10  connects the respective upstream photovoltaic module  5  and the respective downstream photovoltaic module  5  with a series-type connection, as shown in  FIG.  2   . In detail, the first bridge terminal  23   a,  the second bridge terminal  23   b  and the third bridge terminal  23   c  of the first bridge connector  23  are respectively connected to the third line terminal  18   a,  the fourth line terminal  18   b  and to the module cathode terminal  18   c  of the upstream photovoltaic module  5  and the first bridge terminal  24   a,  the second bridge terminal  24   b  and the third bridge terminal  24   c  of the second bridge connector  24  are respectively connected to the first line terminal  17   a,  the second line terminal  17   b  and the module anode terminal  17   c  of the downstream photovoltaic module  5 . 
     In an embodiment, the series bridge module  10  is electrically and structurally symmetrical (for 180° rotations relative to the centre) and the first bridge connector  23  and the second bridge connector  24  may be equally connected to a respective anode connector  17  or to a respective cathode connector  18 . By contrast, if for instance the conductive lines  20 ,  21  of the photovoltaic modules  5  are not arranged on opposite sides of the photovoltaic devices  15 , but are adjacent one another as in  FIG.  4   , the photovoltaic modules  5  and the series bridge module  10  may be provided with a safety device (not shown) preventing the connection between the first bridge connector  23  and the anode connector  17  and between the second bridge connector  24  and the cathode connector  18 . 
     One of the parallel bridge modules  11 , all identical between each other, is shown in  FIG.  6   . The parallel bridge module  11  comprises a substrate  25 , for instance a printed circuit board, a first bridge connector  27  and a second bridge connector  28 , having each a respective first bridge terminal  27   a ,  28   a,  a respective second bridge terminal  27   b ,  28   b  and a respective third bridge terminal  27   c,    28   c.  The first bridge terminal  27   a  and the second bridge terminal  27   b  of the first bridge connector  27  are directly connected respectively to the first bridge terminal  28   a  and to the second bridge terminal  28   b  of the second bridge connector  28 . Furthermore, in the first bridge connector  27  the third bridge terminal  27   c  is connected to the first bridge terminal  27   a  and in the second bridge connector  28  the third bridge terminal  28   c  is connected to the second bridge terminal  28   b.    
     The first bridge connector  27  and the second bridge connector  28  are configured to connect respectively to the cathode connector  18  of the upstream photovoltaic module  5  and to the anode connector  17  of the downstream photovoltaic module  5 . Each parallel bridge module  11  connects the respective upstream photovoltaic module  5  and the respective downstream photovoltaic module  5  with a parallel-type connection, as shown in  FIG.  2   . In detail, the first bridge terminal  27   a,  the second bridge terminal  27   b  and the third bridge terminal  27   c  of the first bridge connector  27  are respectively connected to the third line terminal  18   a,  the fourth line terminal  18   b  and the module cathode terminal  18   c  of the upstream photovoltaic module  5  and the first bridge terminal  28   a,  the second bridge terminal  28   b  and the third bridge terminal  28   c  of the second bridge connector  28  are respectively connected to the first line terminal  17   a,  the second line terminal  17   b  and the module anode terminal  17   c  of the downstream photovoltaic module  5 . 
     In practise, the series bridge modules  10  and the parallel bridge modules  11  connect the first conductive lines  20  of all the photovoltaic modules  5  between each other and all the second conductive lines  21  between each other. Therefore, electrically, the first conductive lines  20  and the second conductive lines  21  are common to the photovoltaic modules  5  of the string  6 . 
     Each series bridge module  10  connects the photovoltaic devices  15  (module cathode terminal  18   c ) of the respective upstream photovoltaic module  5  in series to photovoltaic devices  15  (module anode terminal  17   c ) of the respective downstream module  5 . 
     Each parallel bridge module  11  connects the module cathode terminal  18   c  of the upstream photovoltaic module  5  to the second conductive lines  21  (electrically common to all the photovoltaic modules  5  of the string  6 ) and the module anode terminal  17   c  of the downstream photovoltaic module  5  to the first conductive lines  20  (electrically common to all the photovoltaic modules  5  of the string  6 ). In practice, each parallel bridge module  11  defines, in a parallel connection, the connection to the higher potential line of the anode terminal of a photovoltaic module  5  and the connection to the lower potential line of the cathode terminal of an adjacent photovoltaic module  5 . 
     In the herein described embodiment, the first bridge connector  23  and the second bridge connector  24  of the series bridge modules  10  and of the parallel bridge modules  11  are of the male type and connect to respective female connectors (cathode connector  18  and anode connector  17  respectively) by insertion in parallel to the respective substrate  22  and substrate  14  of the respective photovoltaic modules  5 , as shown in  FIGS.  7  and  8   . The first bridge connector  23  and the second bridge connector  24  may also be of a different type, arranged in a comb-like manner ( FIG.  9   ) by insertion in a direction perpendicular to the substrate  22  and substrate  14  of the respective photovoltaic modules  5  into correspondingly oriented female connectors. The connection of the first bridge connector  23  and of the second bridge connector  24  of the series bridge modules  10  and of the parallel bridge modules  11  with the cathode connectors  18  and anode connectors  17  of the photovoltaic modules  5  is in any case obtained without welding. 
     The string beginning module  7  ( FIG.  10   ) has a first distribution connector  30 , connected to the distribution line  12 , and a string beginning connector  31 . 
     The string beginning connector  31  is coupled to the anode connector  17  of the photovoltaic module  5  at the beginning end of the string  6 . With reference to such anode connector  17 , the string beginning connector  31  has a respective first line terminal  31   a  connected to the first line terminal  17   a;  a respective second line terminal  31   b  connected to the second line terminal  17   b;  and a string anode terminal  31   c  connected to the module anode terminal  17   c.  Furthermore, the first line terminal  31   a  and the second line terminal  31   b  of the string beginning module  7  are respectively connected to a first distribution terminal  30   a  and a second distribution terminal  30   b  of the first distribution connector  30 . 
     The string finishing module  8  ( FIG.  11   ) has a second distribution connector  32 , connected to the distribution line  12 , and a string finishing connector  33 . 
     The string finishing connector  33  is coupled to the cathode connector  18  of the photovoltaic module  5  at the finishing end of the string  6 . With reference to such cathode connector  18 , the string finishing connector  33  has a respective first line terminal  33   a  connected to the third line terminal  18   a;  a respective second line terminal  33   b  connected to the fourth line terminal  18   b;  and a string cathode terminal  33   c  connected to the module cathode terminal  18   c.  Furthermore, the first line terminal  33   a  and the second line terminal  33   b  of the string finishing module  8  are respectively connected to a first distribution terminal  32   a  and a second distribution terminal  32   b  of the second distribution connector  32 . 
     Thanks to bridge modules  10 ,  11 , it is possible to combine three or more identical photovoltaic modules  5  between each other when being assembled in an extremely flexible way to obtain voltages and currents required by the specific application. In particular, the photovoltaic module  5  of a same string  6  may be connected in series-parallel combinations (as shown in  FIGS.  2  and  14   ), all in series ( FIGS.  12  and  15   ) or all in parallel ( FIGS.  13  and  16   ) between the first conductive line  20  and the second conductive line  21 . In particular, in the configuration of  FIGS.  2  and  12    the photovoltaic modules  5  are connected in series in pairs by series bridge modules  10 . Furthermore, the consecutive photovoltaic module pairs  5  are connected in parallel between the first conductive line  20  and the second conductive line  21  by parallel bridge modules  11  connected at the beginning and at the finishing of each series of photovoltaic modules  5 . It must also be understood that the series may contain any number of photovoltaic modules  5 . The number of photovoltaic modules  5  in each series and the number of series of photovoltaic modules  5  respectively determine the maximum voltage and maximum current which the photovoltaic converter  3  is able to supply. 
     It is finally clear that modifications and variants can be made to the disclosed photovoltaic converter, without departing from the scope of the present invention, as defined in the enclosed claims.