Patent Publication Number: US-2012033392-A1

Title: Modular Junction Box for a Photovoltaic Module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. provisional patent application No. 61/372,065 filed Aug. 9, 2010, which is incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter described and/or illustrated herein relates generally to photovoltaic (PV) modules, and more particularly, to a junction box for interconnecting PV modules with a power distribution system. 
     To produce electricity from solar energy, PV modules include a plurality of PV cells interconnected in series and/or parallel, according to the desired voltage and current parameters. PV cells are essentially large-area semiconductor diodes. Due to the photovoltaic effect, the energy of photons is converted into electrical power within a PV cell when the PV cell is irradiated by a light source, such as sunlight. Within a PV module, the PV cells are typically sandwiched between a transparent panel and a dielectric substrate. The PV cells within the PV module are typically interconnected by an electrically conductive foil, such as a metallic foil. A PV module is also known as a PV panel or a solar panel. 
     PV modules are often interconnected, in series and/or parallel, to create a PV array. Junction boxes are typically used to electrically connect the PV modules to each other and also connect the PV array to an electrical power distribution system. Conventional junction boxes include a housing that is mounted on the dielectric substrate of the corresponding PV module. The housing includes electrical contacts, referred to herein as housing contacts, that engage the conductive foil to electrically connect the PV module to the junction box. At least one conventional junction box also includes a printed circuit board (PCB). Diodes and other electric circuitry may be installed on the printed circuit board. The conventional diodes include integral heat sinks to help dissipate heat within the junction box. 
     During assembly, the conductive foil received from the PV module is electrically connected to the junction box by inserting the conductive foil through an opening formed through the dielectric substrate. The conductive foil is then inserted into the junction box and wrapped around the housing contact, which may be a spring clip for example, to electrically connect the PV module to the housing contact. The PCB is then installed such that a clip installed on the PCB, referred to herein as a PCB contact, mates with a respective housing contact. More specifically, during installation of the PCB, inserting the PCB contact into the housing contact causes the conductive foil to deform. The deformed conductive foil forms an electrical path between the housing contact and the PCB contact. Because the conductive foil is disposed between the PCB contact and the housing contact, the combination of the PCB contact and the housing contact causes the foil to deform between the contacts thereby maintaining the foil in a relatively fixed position. 
     Frequently, opening the junction box is not feasible, as some conventional junction boxes are welded shut or are glued shut with epoxy or are an integral part of the PV module. Therefore, in the event of a failure, such as resulting from a problem on the PCB within the junction box, replacing or upgrading that PCB is often impossible without destroying the junction box and/or the PV module. In instances where the junction box is integral with the PV module, the entire integrated junction box/PV module must be replaced even if the failure is from the PCB within the junction box. In other instances, some junction boxes, even if able to be opened, are fully potted with epoxy or sealant and replacing the PCB would be very difficult due to the need to remove the epoxies or sealants. In yet other instances where the junction box may be more easily opened, to replace or upgrade the PCB, the conventional PCB may be removed from the junction box. However, removing the PCB from such a junction box may cause the foil to become damaged, or dislodged or misaligned from the housing contact. When a new or upgraded PCB is installed, the installer must manually replace or align the foil with respect to the housing contact. The installer must then ensure that the foil remains positioned within the housing contact while simultaneously inserted the PCB contact into the housing contact. However, it is often difficult for the installer to properly align the foil within the housing contact while simultaneously inserting the PCB contact into the housing contact. The foil may also become damaged while either removing or installing the PCB. 
     These various approaches, if even possible, of replacing a PCB within a junction box for a PV module can be very expensive and involve intensive labor. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, a junction box for electrically connecting a photovoltaic (PV) module to a power distribution system is provided. The PV module has a plurality of conductors for electrically connecting the PV module to the junction box. The junction box includes a housing having a mounting side configured to be mounted on the PV module and a power transfer structure mounted within the housing. The power transfer structure includes a plurality of conductive connectors and a transfer interface. Each of the conductive connectors forms an electrical interface to the PV module. The transfer interface couples the junction box to the power distribution system. The junction box also includes a user-removable control board mounted within the housing, the power transfer structure interfaces with said control board to convey power from the PV module to the control board via the power transfer structure. According to specific embodiments, the control board may be removable from the junction box to be replaced or to provide upgraded features. The control board can also provide a shut-off circuit operable to interrupt power transfer between the PV module and the power transfer structure, or may provide circuitry to adjust an output from the PV module to substantially match a maximum power point for the PV array. 
     In another embodiment, an electrical isolation device for coupling to at least one PV module is provided. The electrical isolation device includes a junction box and a safety isolation device coupled to the junction box, and the safety isolation device is configured to transmit a communication signal to the junction box. The junction box is configured to operate in a first or second mode based on the communication signal. The communication signal may be sent via a wireless transmission or may be sent over the power line, in various specific embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially exploded perspective view of an exemplary embodiment of a junction box and photovoltaic (PV) module assembly. 
         FIG. 2  is an exploded view of the junction box assembly shown in  FIG. 1 , according to a specific embodiment. 
         FIG. 3  is a top perspective view of the power transfer board shown in  FIG. 2 . 
         FIG. 4  is a bottom perspective view of the power transfer board shown in  FIG. 2 . 
         FIG. 5  is a side view of the power transfer board shown in  FIG. 2 . 
         FIG. 6  is a top perspective view of the power transfer structure built into the housing, as an alternative embodiment to the power transfer board shown in  FIG. 2 . 
         FIG. 7  is a top perspective view of the control board shown in  FIG. 2 . 
         FIG. 8A  is a side view of the control board shown in  FIG. 2 , according to a specific embodiment. 
         FIG. 8B  is a side view of the power transfer board shown in  FIG. 2  coupled to the control board shown in  FIG. 2 . 
         FIG. 9  is a bottom perspective view of another exemplary control board that may be used with the junction box shown in  FIG. 1 . 
         FIG. 10  is a top perspective view of the control board shown in  FIG. 9 . 
         FIG. 11  is a schematic illustration of the control board shown in  FIG. 9  in a first operational mode. 
         FIG. 12  is a schematic illustration of the control board shown in  FIG. 9  in a second operational mode. 
         FIG. 13  is a schematic illustration of the control board shown in  FIG. 9  in a third operational mode. 
         FIG. 14  is a schematic illustration of yet another exemplary control board that may be used with the junction box shown in  FIG. 1 . 
         FIG. 15  is a schematic illustration of a further exemplary control board that may be used with the junction box shown in  FIG. 1 . 
         FIG. 16  is a schematic illustration of another exemplary control board that may be used with the junction box shown in  FIG. 1 . 
         FIG. 17  illustrates an exemplary system that may include the junction box and control boards described in  FIGS. 1-16 . 
         FIG. 18  illustrates an exemplary system that may include the junction box and control boards described in  FIGS. 1-16 . 
         FIG. 19  is a schematic illustration of the control board shown in  FIG. 18 . 
         FIG. 20  is a graphical illustration of exemplary MPP&#39;s that may be generated by the PV modules shown in  FIG. 18 . 
         FIG. 21  is a simplified electrical schematic illustration of a portion of the control board shown in  FIG. 18 . 
         FIG. 22  is a simplified electrical schematic illustration of another control board that may be used with the junction box shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION 
       FIG. 1  is a partially exploded perspective view of an exemplary junction box and photovoltaic (PV) module assembly  10 . The assembly  10  includes a PV module  12  and a junction box  14 . Only a portion of the PV module  12  is shown herein. The PV module  12  includes a dielectric substrate  16 , a transparent panel  18 , and a plurality of PV cells  20  held between the dielectric substrate  16  and the transparent panel  18 . When irradiated by a light source (such as, but not limited to, sunlight and/or the like), the PV cells  20  convert the energy of photons into electrical power. Each PV cell  20  may be any type of PV cell, such as, but not limited to, a thin film PV cell and/or a PV cell fabricated using a material such as a monocrystalline silicon, a polycrystalline silicon, a microcrystalline silicon, a cadmium telluride, and/or a copper indium selenide/sulfide material. The PV cells  20  are electrically interconnected with each other, in series and/or parallel, by an electrical foil conductor  22 , such as, but not limited to, a copper foil a zinc foil, and/or the like. The foil conductors  22  are exposed through an opening  26  within the dielectric substrate  16 . In the exemplary embodiment, four foil conductors  22 , e.g. foil conductor  22   a ,  22   b ,  22   c  and  22   d  are exposed through the opening  26 . However, it should be realized that more, or less, than four foil conductors  22  may be inserted through the opening  26 . The junction box  14  also includes an opening  28  (shown in  FIG. 2 ) that receives the foil conductors  22  therethrough. The opening  28  enables the foil conductors  22  to be electrically coupled to various components mounted within the junction box  14  as discussed in more detail below. 
     The junction box  14  is mounted on the PV module  12  for electrically connecting the PV module  12  to a power distribution system (not shown). The power distribution system conveys electrical power generated by the PV module  12  to an electrical load (not shown), an electrical storage device (not shown), and/or the like. The junction box  14  may also electrically connect the PV module  12  to other PV modules (not shown). For example, a plurality of PV modules may be mechanically and electrically interconnected, in series and/or parallel, to create a PV array (not shown). 
     The transparent panel  18  of the PV module  12  is transparent to light emitted from the light source. The transparent panel  18  may be transparent to any wavelengths of electromagnetic radiation from any light source. In one embodiment, the transparent panel  18  includes only a single layer. Optionally, the transparent panel  18  may include any number of layers greater than one. Each layer of the transparent panel  18  may be fabricated from the same or different material(s) from other layers of the transparent panel  18 . Similarly, although shown as including only one layer, the dielectric substrate  16  may include any number of layers. Each layer of the dielectric substrate  16  may be fabricated from the same or different material(s) from other layers of the dielectric substrate  16 . 
       FIG. 2  is an exploded view of the junction box  14  shown in  FIG. 1 , according to a specific exemplary embodiment. In the exemplary embodiment, the junction box  14  includes a housing  30 , a power transfer board  32 , a control board  34 , a cover  36 , and a gasket  38  configured to be installed between the housing  30  and the cover  36 . The housing  30  has an exterior side  40  and an interior side  42 . The housing  30  also includes a pair of mating interfaces  44 . The mating interfaces  44  are configured to mate with a pair of corresponding mating connectors  46  of an external system  48 . The external system  48  may include, for example, a power distribution system, an electrical load, an electrical storage device, or another junction box that is coupled to another PV module. 
     Each mating interface  44  includes a mating receptacle  50  that receives a conductor  52  of the corresponding mating connector  46  therein. The conductors  52  enable the junction box  14  to be electrically connected to the external system  48 . In addition or alternative to the mating receptacle  50 , each mating interface  44  of the housing  30  may include a plug (not shown) that is received within a receptacle (not shown) of the corresponding mating connector  46 . Although the housing  30  is shown to include two mating interfaces  44 , the housing  30  may have any number of mating interfaces  44  for mating with any number of mating connectors  46 . In some specific embodiments, the mating interfaces  44  may be covered by heat shrink tubing that provides, for example, ultraviolet resistance, flame retardancy, and additional sealing to preventing moisture from the environment from entering the junction box. 
     During assembly, the power transfer board  32  has at least one lock washer  54  that receives a respective mounting post  56  therein, or similar means to secure the power transfer board to the housing  30 , and to securely couple the power transfer board  32  to the mounting post  56 . The foil conductors  22  are electrically coupled to the power transfer board  32 . The control board  34  and the cover  36  are then installed by electrically coupling the control board  34  to the power transfer board  32 . 
     More specifically, the cover  36  includes a plurality of mounting posts  60 . The control board  34  also includes a plurality of push lock washers  62  that are configured to mate with a respective mounting post  60  on the cover  36  such that the control board  34  is securely coupled to the cover  36 . 
     The cover  36  has a plurality of latch members  70  that each mate with a respective recess  72  on the junction box  14  to retain the cover  36  coupled to the housing  30 . The cover  36  also includes at least one arm portion  74  that is disposed on an opposite side of the cover  36 . During assembly, the arm portion  74  slides beneath a flange  76  located on the housing  30 . The arm portion  74  cooperates with the latch members  70  to maintain the cover  36  securely coupled to the housing  30 . The gasket  38  preferably is used to provide a weatherproof seal between the cover  36  and the housing  30 . 
     In the exemplary embodiment, the housing  30  and the cover  36  are fabricated from a substantially rigid, electrical insulating material suitable to receive the power transfer board  32  and the control board  34  therein. More specifically, as discussed above, in the exemplary embodiment, the control board  34  is coupled to the cover  36 . Accordingly, the control board  34  is installed and removed in conjunction with the cover  36 . During operation, heat generated by the control board  34 , and/or the power transfer board  32 , is dissipated by transferring the heat from the control board  34  to the cover  36 . As such, the cover  36  functions as a heat sink to enable heat generated by the various components installed within the housing  30  to be dissipated through the cover  36 . To promote heat dissipation, the cover  36  (or portion thereof) is fabricated from a material that is also thermally conductive. Such thermally conductive materials may include, for example, a thermally conductive epoxy and/or a thermally conductive adhesive. In another example, the cover  36  may be made of a polyphenaline sulfide material having thermally conductive filler, such as RTP 1300x88127 available from RTP Company. 
     A more detailed description of the power transfer board  32 , the control board  34 , and a method of coupling the control board  34  to the power transfer board  32  are described below, in accordance with a specific embodiment. 
       FIG. 3  is a top perspective view of the power transfer board  32  shown in  FIG. 2 .  FIG. 4  is a bottom perspective view of the power transfer board  32  shown in  FIG. 2 .  FIG. 5  is a side view of the power transfer board  32  shown in  FIG. 2 . In the exemplary embodiment, the power transfer board  32  is a printed circuit board that includes various devices to enable the power transfer board  32  to convey power generated by the PV module  12  to the system  48 . The power transfer board  32  also includes various devices to enable the power transfer board  32  to be electrically coupled to the control board  34 . 
     The power transfer board  32  has a first side  100  and an opposing second side  102 . As discussed above, in the exemplary embodiment, the power transfer board is a PCB. Accordingly, the first and second sides  100  and  102  are substantially planar such that the first side  100  is substantially parallel to the second side  102 . The power transfer board  32  also includes a first edge  104  and an opposing second edge  106 . In the exemplary embodiment, the first edge  104  is located proximate to the opening  28  (shown in  FIG. 2 ) to enable the foil conductors  22  to be electrically coupled to the power transfer board  32 . The second edge  106  is located proximate to the mating interfaces  44  (also shown in  FIG. 2 ) to enable the external system  48  to be electrically coupled to the power transfer board  32 . 
     The power transfer board  32  includes a plurality of foil connectors  110 . Each foil connector  110  is configured to receive a respective foil conductor  22  therein to enable the PV module  12  to be electrically coupled to the power transfer board  32  via the foil conductors  22 . Each foil connector  110  includes a foil receptacle  112  and a foil output  114 . The foil receptacle  112  is configured to receive a foil conductor  22  therein. The foil output  114  is electrically coupled to a transfer interface  140  that is discussed in more detail below. In one embodiment, the foil connector  110  including the foil receptacle  112  are disposed on the first side  100  of the power transfer board  32  (shown in  FIG. 3 ). The foil receptacle  112  is positioned proximate to the first edge  104 . As shown in  FIG. 2 , the first edge  104  is located proximate to the opening  28  to enable foil conductors  22  inserted through the opening  28  to be easily inserted into the foil receptacles  112 . The foil output  114  is disposed on the second side  102  of the power transfer board  32  (shown in  FIG. 4 ). Optionally, the foil output  114  may be disposed on the first side  100 . 
     As shown in  FIG. 5 , the foil connector  110  also includes a pair of contacts  116  that are configured to physically and electrically couple the foil conductor  22  to the foil connector  110 . The pair of contacts  116  are arranged to enable the foil conductor  22  to be inserted and retained within the foil connector  110  approximately parallel to the first side  100 . The pair of contacts  116  may be spring-loaded contacts that utilize spring force to retain the foil conductor  22  within the foil connector  110 . Optionally, the pair of contacts  116  may be opened and/or closed using a device such as a screw, for example. During assembly, the pair of contacts  116  are separated, either by mechanical pressure on the spring or by optionally loosening the screw. The foil conductor  22  is then inserted between the pair of contacts  116  and the mechanical pressure is released or the screw is tightened such that the foil conductor  22  is retained within and electrically coupled to the foil connector  110 . It should be realized that the quantity of foil connectors  110  is determined based on the desired quantity PV modules  12  to be electrically coupled to the power transfer board  32  via the foil conductors  22 .  FIG. 3  illustrates four foil connectors  110 , however, the power transfer board  32  may have fewer than or more than four foil connectors  110 . 
     According to specific embodiments, the power transfer structure or board  32  also includes a plurality of external system connectors  130 . As discussed above, the external system  48  may be, for example, a power distribution system, an electrical load, an electrical storage device, or another junction box that is coupled to another PV module. Accordingly, the external system connectors  130  are each configured to receive a system conductor, such as conductor  52 , therein. Each system connector  130  includes a system conductor receptacle  132  and a system output  134 . The system receptacle  132  is configured to receive the system conductor  52  therein. The system output  134  is configured to couple to the transfer interface  140  that is discussed in more detail below. In one embodiment, the system connector  130  including the system receptacle  132  is disposed on the first side  100  of the power transfer board  32  (shown in  FIG. 3 ), and the system output  134  is disposed on the second side  102  of the power transfer board  32  (shown in  FIG. 4 ). Optionally, the system output  134  may be disposed on the first side  100 . Of course, it should be recognized that the system connectors  130  may be provided on the bottom or other part of the housing  30 , such as in the cover, according to other embodiments. 
     As shown in  FIG. 5 , the system connector  130  also includes a pair of contacts  136  that are configured to physically couple the system conductor  52  to the system connector  130 . In the exemplary embodiment, the pair of contacts  136  are arranged to enable the system conductor  52  to inserted and retained within the system connector  130  approximately parallel to the first side  100 . In one embodiment, the pair of contacts  136  may be spring-loaded contacts are utilize spring force to maintain the system conductor  52  within the system connector  130 . Optionally, the pair of contacts  136  may be opened and/or closed using a device such as a screw, for example. During assembly, the pair of contacts  136  are separated either by mechanical pressure on the spring or by optionally loosening the screw. The system conductor  52  is then inserted between the pair of contacts  136  and the mechanical pressure is released or the screw is tightened such that the system conductor  52  is retained within and electrically coupled to the system connector  130 . It should be realized that the quantity of system connectors  130  is determined based on the desired external systems  48  to be electrically coupled to the power transfer board  32  via the system conductors  52  and that although  FIG. 3  illustrates two system connectors  130 , the power transfer board  32  may have fewer than or more than two system connectors  130 . In some embodiments, the system connectors  130  and  132  may be AC, rather than DC, connectors for systems where the DC to AC conversion is performed in the junction box. In some embodiments connectors  130  or  132  may be placed on the control board  34  and omitted from the power transfer board. In some embodiments connectors  72  may be combined into one output point that includes both conductors. 
     The power transfer board  32  also includes at least one transfer interface  140 , according to a specific embodiment. The transfer interface  140  enables electrical signals received at both the foil connectors  110  and the system connectors  130  to be transmitted or conveyed to the control board  34 . The transfer interface  140  also enables the control board  34  to mechanically engage and disengage from the transfer interface  140  separate and independent from the electrical connection of the foil conductor  22  to the foil receptacle  112 . 
     The transfer interface  140  may be a receptacle that includes a plurality of transfer inputs  142  and a plurality of transfer outputs  144 , according to a specific embodiment. During assembly, the transfer interface  140  is configured to mate with a corresponding device installed on the control board  34 . The corresponding device is discussed in more detail below. The transfer interface  140  includes four transfer inputs  142  for transmitting electrical signals from/to the foil connectors  110  and the system connectors  130 . Optionally, the transfer interface  142  may include more or less than four inputs  142 . The transfer inputs  142  are electrically coupled to the transfer outputs  144  to enable electrical signals received at the transfer inputs  142  to be transmitted or conveyed to the control board  34  via the transfer outputs  144 . It should be realized that the quantity of transfer interfaces  140  is determined based on the PV module  12  and external systems  48  to be electrically coupled to the control board  34  via the power transfer board  32 . Although  FIG. 3  illustrates three transfer interfaces  140 , wherein one transfer interface  140  is being utilized and two transfer interfaces  140  are spares, the power transfer board  32  may have fewer than or more than three transfer interfaces  140 . Also, it should be recognized that  FIG. 3  and  FIG. 4  show a cutout within board  32  to accommodate components that may be on control board  34 , but such cutouts are optional and would not be needed when components on control board  34  have a sufficiently low profile. 
     In one embodiment, the transfer inputs  142  are disposed on the second side  102  of the power transfer board  32  (shown in  FIG. 4 ), and the transfer outputs  144  are disposed on the first side  100  of the power transfer board  32  (shown in  FIG. 3 ). Optionally, the transfer inputs  142  may be disposed on the first side  100 . As shown in  FIG. 5 , the transfer interface  140  includes four contacts  146  that are configured to physically couple the transfer interface  140  to both the foil connectors  110  and the system connectors  130  to the transfer interface  140 . The foil outputs  114  are electrically coupled to the transfer inputs  142  using a plurality of electrical traces  150  that are formed on the second side  102 . Optionally, the foil outputs  114  are electrically coupled to the transfer inputs  142  using hardwires. The system outputs  134  are electrically coupled to the transfer inputs  142  using a plurality of electrical traces  152  that are formed on the second side  102 . Optionally, the system outputs  134  may be electrically coupled to the transfer inputs  142  using hardwires. 
     According to other specific embodiments such as shown in  FIG. 6 , junction box  14  does not include a power transfer board  32  as described in  FIGS. 3-5 , but instead incorporates a power transfer structure that interfaces with a removable PCB (control board  34 ) that may be disposed within the cover  36  of the junction box  14 .  FIG. 6  is a top perspective view of the power transfer structure integrally built into the housing, as an alternative embodiment to the power transfer board shown in  FIG. 2 . In such embodiments, there are conductive connectors (such as foil connectors  110  with foil receptacles  112 ) integrally formed within (such as by being molded into) the interior surface of the material of housing  30 . These conductive connectors interface to the PV module with conductive leads including but not limited to foil conductors  22 . When the cover  36  is fastened to box  14 , the conductive connectors can make direct electrical and mechanical connection via transfer interfaces to circuitry formed on the control board  34 . Further, system connectors  130  may be integrally formed on the interior surface of housing  30 , such that the system conductors  52  can make electrical and mechanical contact with circuitry on the control board  34  when the cover  36  is closed. In these embodiments, the mounting posts  60  of cover  36  may be partially constructed of conductive material and configured so as to be inserted, through vias in control board  34 , into transfer interfaces  184 , which may be holes formed in conductive connectors  110 , and into transfer interfaces  194 , which may be holes in system connectors  130 . The individual foils may be connected similarly as in other embodiments through clamping, soldering, welding, or gluing and their attachments are not affected by placement or removal of the cover. It should be recognized that the description of  FIGS. 11-15 , according to specific embodiments, specifies power transfer boards but in other embodiments the power transfer boards may be eliminated by integrating the conductive connectors into the interior surface of housing  30  as discussed above. 
       FIG. 7  is a bottom perspective view of the control board  34  shown in  FIG. 2 .  FIG. 8A  is a side view of the control board shown in  FIG. 2 . The control board  34  includes at least one mating connector  160  that mates with the transfer interface  140 . The mating connector  160  enables the control board  34  to be both physically and electrically coupled to the power transfer structure (e.g., board  32 ). The mating connector  160  also enables electrical signals to be transmitted between the control board  34  and the power transfer board  32 . Accordingly, the mating connector  160  enables the control board  34  to receive electrical inputs from the external system  48  and the foil conductors  22 , via the power transfer board  32 , and transmit electrical outputs to the external system  48  and the foil conductors  22 , via the power transfer board  32 . The control board  34  is configured to modify or otherwise operate on the received electrical signals as is discussed in more detail below. 
     The control board  34  has a first side  162  and an opposing second side  164 . As discussed above, in the exemplary embodiment, the control board  34  is a PCB. Accordingly, the first and second sides  162  and  164  are substantially planar and the first side  162  is substantially parallel to the second side  164 . The control board  34  also includes a plurality of mating connectors  160  that is equal to the quantity of transfer interfaces  140  installed on the transfer board  32 . Each mating connector  160  is configured to mate with a respective transfer interface  140  to enable the control board  34  to be electrically and mechanically coupled to the power transfer board  32 . Each mating connector  160  includes a plurality of pins  166  that are each configured to electrically couple to a respective transfer output  144  in the transfer interface  140 . In one embodiment, the mating connector  160  is a female device that is inserted into the transfer interface  140 . Optionally, the transfer interface  140  is a female device that is inserted into the mating connector  160 . 
       FIG. 8B  is a side view of the control board  34  coupled to the transfer board  32 . As discussed above, to facilitate coupling the control board  34  to the transfer board  32 , the mating connector  160  on the control board  34  is electrically and mechanically coupled to the transfer interface  140  on the power transfer board  32 . To facilitate coupling the mating connector  160  to the transfer interface  140 , the transfer board  32  also includes at least one pair of guides  170 . As shown in  FIGS. 3 and 8B , the pair of guides  170  are mounted to the power transfer board  32 . The pair of guides  170  includes at least a first guide  172  that is disposed proximate the transfer interface  140  toward the second edge  106  and a second guide  174  that is disposed proximate to the transfer interface  140  toward the first edge  104 . As shown in  FIGS. 3 and 8B , a height  176  of the pair of guides  170  is greater than a height  178  of the transfer interface  140  to enable the mating connector  160  to be fully inserted into the transfer interface  140  while maintaining an adequate separation between the control board  34  and the power transfer board  32 . The shape of the pair of guides  170  enables an installer to initially place the mating connector  160  proximate to the transfer interface  140  before mating the two together. 
     A technical effect of the junction box  14  described herein is to provide a junction box that is configured to mount to a PV module. The junction box is upgradeable without modifying the electrical connections between the junction box and the PV module and also without modifying the electrical connections between the junction box and the external system. The electrical connections between the junction box and both the PV module and the external system are made on the power transfer structure, such as for example a power transfer board. The outputs from the power transfer board are conveyed to the control board via the transfer interface and the mating connector. The mating connector on the control board enables the control board to be removed or replaced from the junction box without disturbing any of the electrical connections between the junction box and both the PV module and the external system. Accordingly, the junction box may be upgraded by removing the control board and replacing the control board with another control board that has additional features without modifying the connections between the power transfer board and the PV module. Additionally, the junction box cover, with the attached control board, may be replaced with a new or different junction box cover that includes a new or different control board connected thereto. The junction box described herein thus functions as a universal junction box that enables solar module manufacturers to produce one type of PV modules with ‘universal’ junction boxes that can later be customized to a desired configuration. In some embodiments the control board may be removable but not an integral part of the cover, which cover may be removed without affecting the functionality of the circuit—the cover is opened in the first step, whereas the control board can be removed separately for repair or replacement. 
     For example, the control board described herein may be modified to include a circuit protection module having bypass diode functionality and/or additional over-voltage and over-current protection components. The junction box cover is fabricated from a thermally conductive material and functions as a heat sink to dissipate heat generated by both the power transfer board and the control board. The control board may also be configured to perform circuit protection functions, communication functions, and other functionalities. Such additional functionalities may include, for example, modifying the control board to accept a micro-inverter (DC to AC converter with maximum power point tracking, optional communication features, and similar functionalities), such as described below. A conventional junction box may be upgraded during manufacturing or field-modified to produce the exemplary junction box described herein. 
       FIG. 9  is a bottom perspective view of an exemplary control board  200  that may be coupled to the power transfer structure or board  32  shown in  FIG. 1 .  FIG. 10  is a top perspective view of the exemplary control board  200 . As shown in  FIG. 9 , the control board  200  has a first side  202  and an opposing second side  204 . In the exemplary embodiment, the control board  200  is a PCB. Accordingly, the first and second sides  202  and  204  are substantially planar and the first side  202  is substantially parallel to the second side  204 . The control board  200  also includes a plurality of mating connectors  206  that is equal to the quantity of transfer interfaces  140  installed on the transfer structure or board  32 . 
     Each mating connector  206  is installed on the second side  204  to enable the control board  200  to be electrically and mechanically coupled to the power transfer structure as discussed above with respect to the control board  34 . For simplicity, only one mating connector  206  is shown in  FIG. 10 . However, it should be realized that the junction box  14  may include a plurality of mating connectors  206 . The combination of the transfer interfaces  140  (shown in  FIG. 2 ) and the mating connectors  206  enable the outputs from the foil connectors  110 , on the power transfer structure or board  32 , to be conveyed to the control board  200  via the transfer interfaces  140  and the mating connectors  206 . Additionally, the outputs/inputs from the system outputs  134  (shown in  FIG. 2 ) are conveyed to the control board  200  via the transfer interfaces  140  and the mating connectors  206 . 
     The control board  200  also includes a PV module shut-off circuit  210  that is installed on the first side  202 . The circuit  210  is electrically coupled to at least one of the mating connectors  206  such that the circuit  210  receives electrical signals from both the external system  48  and the PV module  12  via the system connectors  130  and the foil connectors  110 , respectively (both shown in  FIG. 3 ). During operation, the shut-off circuit  210  is operable to turn off the PV module  12  when the PV module  12  has been determined to be defective. Additionally, the shut-off circuit  210  is operable to turn off the PV module  12  based on an electrical demand of the system, and/or environmental conditions such as temperature, water ingress, etc., for example. 
       FIG. 11  is a simplified schematic illustration of the shut-off circuit  210  coupled to the PV module  12  and the system  48  via the power transfer structure or board  32 , according to a specific embodiment. In this embodiment, the PV module  12  includes at least three strings of cells, e.g. a string  220 , a string  222  and a string  224 . Each string  220 ,  222  and  224  includes a plurality of cells  226  that are electrically coupled in series. Moreover, in this embodiment, the strings  220 ,  222  and  224  are electrically coupled together in series. Accordingly, the PV module  12  has four foil conductors  230 ,  232 ,  234  and  236  that are exposed through the opening  26  within the dielectric substrate  16  (shown in  FIG. 1 ). Additionally, the junction box  14  includes four foil connectors  110  (shown in  FIG. 3 ) for receiving the foil conductors  230 ,  232 ,  234  and  236  therein. The electrical signals conveyed from the four foil conductors  230 ,  232 ,  234  and  236  are conveyed to the control board  200 , via the power transfer board  32  as discussed above. Accordingly, the control board  200  includes four conductors or traces  240 ,  242 ,  244  and  246  that electrically couple the shut-off circuit  210  to each respective foil conductor  230 ,  232 ,  234  and  236  via the mating connector  206 . 
     The shut-off circuit  210  includes at least one diode (often three diodes  250 ,  252  and  254 ) installed on the control board  200 . Optionally, the diodes  250 ,  252  and  254  may be installed on the power transfer board  32  shown in  FIG. 2  according to another embodiment. If there are three diodes the first diode  250  is electrically coupled between the first and second traces  240  and  242 , and as such, is electrically coupled between the input and output of the first string  220 . The second diode  252  is electrically coupled between the second and third traces  242  and  244 , and as such, is electrically coupled between the output of the first string  220 /input of the second string  222  and the output of the second string  222 . The third diode  254  is electrically coupled between the third and fourth traces  244  and  246 , and as such, is electrically coupled between the output of the second string  222 /input of the third string  224  and the output of the third string  224 . As shown in  FIG. 11 , the trace  240  is the input to the PV module  12  and is therefore coupled to the input of the first string  220 . The trace  246  is the output from the PV module and is therefore coupled to the output of the third or final string  224  in the PV module  12 . 
     The shut-off circuit  210  further includes a three-stage relay  260 . The three-stage relay  260  includes a relay  261 , a primary relay  262  and a secondary relay  264  that is coupled in series with the primary relay  262 . The relay  261  and the secondary relay  264  are each coupled between the trace  240  and the trace  246  and are therefore electrically coupled between the input and outputs of the PV module  12 . The outputs from the secondary relay  264  are coupled to the inputs of the primary relay  262 . The outputs from the primary relay  262  are also electrically coupled to the system  48 . During operation, the three-stage relay  260  is operable to enable voltage and current to be conveyed from the PV module  12  to the system  48  via the control board  200 . Additionally, the shut-off circuit  210  is configured to electrically isolate the PV module  12  from the system  48 . 
     In the exemplary embodiment, the PV module  12  is configured to be electrically coupled in series with a string of other PV modules (not shown). For example, the PV module  12  may be coupled in series with nine other PV modules (e.g. system  48  represents nine PV modules coupled in series). In the exemplary embodiment, each PV module  12  may generate 60 Volts and an associated current. Accordingly, the PV module array (ten PV modules) may generate approximately 600 Volts DC and an associated current. It should be realized that 600 Volts is exemplary and that an array of PV module may generate more or less than 600 Volts. For example, an array of PV modules may generate 1000 Volts or more. 
     During operation, each junction box  14  is exposed to the cumulative voltage generated by the entire system  48 , e.g. approximately 600-1000 Volts DC. To perform maintenance or repair on an individual PV module, such as PV module  12 , the maintenance personnel is required to electrically isolate the PV module  12  from the system  48 . Conventional PV modules require personnel to electrically “break” the circuit between the PV module  12  and the system  48  using a conventional switch. However, when opening the conventional switch to break the circuit, an electrical arc may occur that may be hazardous to personnel. The control board  200  described herein enables an operator to “break” the electrical connection between the system  48  and the PV module  12  such that the operator is not exposed to an electrical arc that is equivalent to the voltage of the entire electrical system, e.g. 600-1000 Volts. 
     In a first operational mode, shown in  FIG. 11 , the shut-off circuit  210  enables DC voltage and current to be conveyed from the PV module  12  to the system  48  via the control board  200 . More specifically, in the first or normal operational mode, the shut-off circuit  210  is configured such that the relay  261  and the primary relay  262  are each “open” and the secondary relay  264  is “closed”. As shown in  FIG. 11 , when the relay  261  and the primary relay  262  are “open”, voltage and current generated by the PV module  12  are conveyed from the PV module  12 , through the secondary relay  264  to the system  48 , via the power transfer board  32  as discussed above. 
     To electrically isolate the PV module  12  from the system  48 , the shut-off circuit  210  is also configured to operate in a second operational mode shown in  FIG. 12 . More specifically, if the operator desires to electrically isolate the PV module  12  from the system  48 , the operator initially causes the relay  261  to close creating a short circuit across the cross the relay  262  creating a short circuit across the primary relay  262 . The operator may then close the primary relay  262  to create a short circuit within the junction box  14 . In the second operational mode, the relay  261  and both the primary and secondary relays  262  and  264  are closed such that the voltage and current generated by the PV module  12  are not conveyed to the system  48 . Moreover, in the second operational mode, current generated by the PV module  12  is still being channeled between the PV module  12  and the junction box  14 . Therefore, in the second operational mode, the junction box  14  “sees” only the voltage and current generated by the PV module  12  and does not “see” and voltage or current that is generated by any of the other PV modules in the string that represents system  48 . 
     To electrically isolate the PV module  12  from the junction box  14 , the shut-off circuit  210  is also configured to operate in a third operational mode shown in  FIG. 13 . In the third operational mode, the operator causes the secondary relay  264  to open. The relay  261  is then opened. Accordingly, the voltage across the primary relay  262  is approximately 0 Volts thereby reducing any arcs across the primary relay  262 . During operation, the relay  261  generates a relatively small voltage across the primary relay  262 . In the exemplary embodiment, the relay  261  is a MOSFET that facilitates reducing the generation of an electrical arc. Accordingly, in the third operational mode, the primary relay  262  is closed and the relay  261  and the secondary relay  264  are both open. The third operational mode is also referred to herein as the “safe state”. In the safe state, the current generated by the PV module  12  is not being circulated through the junction box  14 . It should be realized that, because the PV module  12  is isolated from the system  48  by closing the relay  261  and the primary relay  262  in the second operational mode, such that when the operator opens the secondary relay  264  to isolate the junction box  14 , the junction box  14  only sees the voltage generated by the single PV module  12 , e.g. approximately 60 Volts in the exemplary embodiment. Therefore, the arc that may be created by opening the secondary relay  264  is significantly less powerful than an arc created by opening a conventional switch. Moreover, because, the junction box  14  sees only the voltage from the single PV module  14 , the junction box  14  may utilize electrical components that suitable for a lower voltage application, thus reducing the overall cost of the junction box  14 . To reconnect the PV module  12  to the system  48 , the secondary relay  264  is initially closed. The primary relay  262  is then opened such that the junction box  14  is again operating in the first operational mode as shown in  FIG. 11 . 
     In the exemplary embodiment, the control board  200  also includes a communication and control device  270  that is electrically coupled to at least the primary and secondary relays  262  and  264 . During operation, the communication and control device  270  is configured to receive an input either locally at the junction box  14  or from a remote location, and operate the primary and secondary relays  262  and  264  based on the received input. In one embodiment, the communication and control device  270  may be hard-wired to the remote location and receive an input over the hard-wired line. Optionally, the communication and control device  270  is configured to receive a wireless transmission from the remote location. 
       FIG. 14  is a schematic illustration of another exemplary control board  300  that may be used with the junction box shown in  FIG. 1 . The control board  300  is substantially similar to the control board  200  shown in  FIGS. 9-13 . In this embodiment, the diodes of control board  200  in circuit  210  have been replaced with electrical switches to enable an operate to electrically isolate a single string in the PV module  12 . For example, the operator may electrically isolate either string  220 ,  222 , and or  224  from transmitting voltage and current to the system  48 . The switches described herein may be used in combination with or separately from the primary and secondary relays  262  and  264  discussed above. In the exemplary embodiment, the control board  300  is a PCB that is configured to mate with the power transfer board  32  also discussed above. 
     The control board  300  includes a first switch  302 , a second switch  304  and a third switch  306  that in the exemplary embodiment are installed on the control board  300 . Optionally, the three switches  302 ,  304  and  306  may be installed on the power transfer board  32  shown in  FIG. 2 . The switches  302 ,  304  and  306  may be any type of electrical switch that is capable of interrupting the flow of electricity. In the exemplary embodiment, the switches  302 ,  304  and  306  are thin-film transistors (TFT) such as Field-Effect Transistors (FET), Metal Oxide Semiconductors (MOSFET)&#39;s, for example. 
     The first switch  302  is electrically coupled between the first and second traces  240  and  242 , and as such, is electrically coupled between the input and output of the first string  220 . The second switch  304  is electrically coupled between the second and third traces  242  and  244 , and as such, is electrically coupled between the output of the first string  220 /input of the second string  222  and the output of the second string  222 . The third switch  306  is electrically coupled between the third and fourth traces  244  and  246 , and as such, is electrically coupled between the output of the second string  222 /input of the third string  224  and the output of the third string  224 . The first switch  302 , second switch  304  and third switch  306  are electrically coupled to the communication and control device  270 . The communication and control device  270  is configured to receive an input either locally at the junction box  14  or from a remote location, and operate the first switch  302 , second switch  304  and third switch  306  based on the received input. In one embodiment, the communication and control device  270  may be hard-wired to the remote location and receive an input over the hard-wired line. Optionally, the communication and control device  270  is configured to receive a wireless transmission from the remote location. 
     During operation, the switches  302 ,  304  and/or  306  may be operated by bypass each individual string  220 ,  222  and/or  224 , respectively. Isolating an individual string or a group of strings enables an operator to control and/or bypass under-performing strings and also enables the operator to monitor the voltage and/or current generate by the individual string. For example, the operator may modify the impedance of the switches  302 ,  304  and/or  306  by modifying the voltage signal transmitted to the switches. Because, in the exemplary embodiment, the switches  302 ,  304  and/or  306  are MOSFETs, in a specific embodiment, modifying the voltage controlling the MOSFET enables the operator to operate each string at various voltage and current outputs. Accordingly, the switches  302 ,  304  and/or  306  may be operated to identify any mismatch in the maximum power point tracking (MPPT) voltage and current and to determine the overall health of each string in the PV module  12 . 
     The information from each string may then be transmitted to a monitoring system, such as communication and control device  270 , for example to enable the operator to identify underperforming or non-operational strings and also determine if a string should be repaired or replaced. Information from the switches  302 ,  304  and/or  306  may also be utilized by the communication and control device  270  to determine the operational mode of the PV module, for example, whether the PV module is operating in the normal mode or the safe state. 
       FIG. 15  is a schematic illustration of another exemplary control board  310  that may be used with the junction box shown in  FIG. 1 . The control board  310  is substantially similar to the control board  200  shown in  FIGS. 9-13 . In the exemplary embodiment, the control board  310  is a PCB that is configured to mate with the power transfer board  32  also discussed above. 
     The control board  310  includes a first switch  312  and a second switch  314  that in the exemplary embodiment are installed on the control board  310 . Optionally, the switches  312  and  314  may be installed on the power transfer board  32  shown in  FIG. 2 . The switches  312  and  314  may be any type of electrical switch that is capable of interrupting the flow of electricity. In the exemplary embodiment, the switches  312  and  314  are electrical/mechanical relays. As shown in  FIG. 15 , the switches  312  and  314  are electrically coupled to the communication and control device  270 . The communication and control device  270  is configured to receive an input either locally at the junction box  14  or from a remote location, and operate the switches  312  and  314  based on the received input. In one embodiment, the communication and control device  270  may be hard-wired to the remote location and receive an input over the hard-wired line. Optionally, the communication and control device  270  is configured to receive a wireless transmission from the remote location. The control board  310  described herein enables an operator to “break” the electrical connection between the system  48  and the PV module  12  such that the operator is not exposed to an electrical arc that is equivalent to the voltage of the entire electrical system, e.g. 600-1000 Volts. 
     In a first operational mode, shown in  FIG. 15 , the switch  312  is connected to the terminal “A” and the switch  314  is open. In this operational mode, the voltage and current generated by the PV module  12  are conveyed from the PV module  12  to the system  48 , via the power transfer board  32  as discussed above. 
     In a second operational mode, to bypass the PV module  12  from the system  48 , the switch  314  is closed to create a short circuit across the PV module  12 . The switch  312  is then moved from position A to position B. After, the switch  312  is in position B, the switch  314  is then re-opened. More specifically, if the operator desires to electrically isolate the PV module  12  from the system  48 , the operator initially causes the switch  314  to close creating a short circuit across the cross the switch  314 . The operator may then move the switch  312  to the B position and reopen the switch  314 . Therefore, in the second operational mode, the junction box  14  “sees” only the voltage and current generated by the PV module  12  and does not “see” and voltage or current that is generated by any of the other PV modules in the string that represents system  48 . 
     To reconfigure the PV module  12  from the second operational mode back to the first operational mode, the operator initially closes switch  314 . The switch  312  is then moved from the B position back to the A position and the switch  314  is again re-opened. The control board shown in  FIG. 15  includes only two relays or switches. Thus the control board  310  has fewer components which reduces the cost of fabricating the control board. Additionally, control board  310  is relatively small in size thus easily retrofittable in a conventional junction box. Moreover, if there is a failure of the switch  312 , the switch  314  may perform the functionality of the switch  312 . The control board  310  also substantially eliminates any electrical arcing that may occur when electrically isolating the PV module. 
       FIG. 16  is a schematic illustration of another exemplary control board  350  that may be used with the junction box shown in  FIG. 1 . The control board  350  is substantially similar to the control board  300  shown in  FIG. 14 . In this embodiment, the first switch  302 , the second switch  304 , and the third switch  306  are each electrically coupled to a respective DC/DC converter. For example, the first switch  302  is electrically coupled to a first isolation power converter  352 , the second switch  304  is electrically coupled to a second isolation power converter  354 , and the third switch  306  is electrically coupled to a third isolation power converter  356 . The control board  350  also includes a processor, such as the communication and control device  270  described above, and a power supply  358 . In the exemplary embodiment, the processor  270  is coupled to a user interface  359  that enables a user to input commands to the processor  270  for controlling the operation of the control board  350 . The communication and control device  270  is configured to receive an input either locally at the junction box  14  or from a remote location, and operate the first switch  302 , the second switch  304  and the third switch  306  based on the received input. In one embodiment, the communication and control device  270  may be hard-wired to the remote location and receive an input over the hard-wired line. Optionally, the communication and control device  270  is configured to receive a wireless transmission from the remote location. 
     As shown in  FIG. 16 , the isolation power converter  352  includes a processor input  360  that is received from the processor  270  and a power supply input  362  that is received from the power supply  358 . The isolation power converter  352  also includes two inputs from the string  220 . Specifically, an input  364  is electrically coupled to the negative side of the string  220  and an input  366  is coupled to a positive side of the string  220 . The isolation power converter  352  also includes an output  368  that is electrically coupled to the switch  302 . 
     Similar to the isolation power converter  352 , the isolation power converter  354  includes a processor input  370  that is received from the processor  270  and a power supply input  372  that is received from the power supply  358 . The isolation power converter  354  also includes two inputs from the string  222 . Specifically, an input  374  is electrically coupled to the negative side of the string  222  and an input  376  is coupled to a positive side of the string  222 . The isolation power converter  354  also includes an output  378  that is electrically coupled to the switch  304 . 
     Additionally, the isolation power converter  356  includes a processor input  380  that is received from the processor  270  and a power supply input  382  that is received from the power supply  358 . The isolation power converter  356  also includes two inputs from the string  224 . Specifically, an input  384  is electrically coupled to the negative side of the string  224  and an input  386  is coupled to a positive side of the string  224 . The isolation power converter  356  also includes an output  388  that is electrically coupled to the switch  306 . 
     During operation, the switches  302 ,  304  and/or  306  may be operated to bypass each individual string  220 ,  222  and/or  224 , respectively. Isolating an individual string or a group of strings enables an operator to control and/or bypass under-performing strings and also enables the operator to monitor the voltage and/or current generated by the individual strings. As discussed above, the various strings forming the PV module  12 , e.g. strings  220 ,  222 , and/or  224 , may be electrically isolated from the array by shorting across the two output terminals from the string using the appropriate switches. For example, to isolate the string  220 , the switch  302  is powered in the open position. In the exemplary embodiment, the FET coupled to each string is activated by a separate gate voltage that is supplied from the respective isolation power converter. When a voltage signal is applied to the FET, the FET is “open” and a short circuit (or shunt) is created across the string. However, when the power signal from the DC/DC converter is terminated, the FET is in the closed position and the string is not short circuited. The operation of the various components is now explained with respect to the string  220  and the FET  302 . However, it should be realized that the other strings, e.g. strings  222  and  224  may be electrically isolated in the same manner as string  220 . 
     In one mode of operation, the string  220  is not electrically isolated. More specifically, during normal operation, when a user desires that electrical power generated by the string  220  be transmitted to an end user, the switch  302  is “closed” or powered. In the exemplary embodiment, the power is transmitted from the power supply  358  to the isolation power converter  352 . Additionally, a command is sent via the input  360  to turn the isolation power converter  352  “ON”. In the ON state, the isolation power converter  352  is enabled to receive an electrical input at the input  362  and transmit an electrical output to the switch  302  via the output  368 . When the isolation power converter  352  is in the “OFF” state, the isolation power converter  352  is disabled. Thus, an electrical signal is not transmitted from the isolation power converter  352  to the switch  302  via the output  368 . 
     In operation, the isolation power converter  352  is configured to operate as a DC/DC converter by modifying the input power received from the power supply  358  to a power level that is suitable to operate the switch  302 . For example, the isolation power converter may transform the power level received from the power supply  358  to a reduced power level that is suitable to operate the switch  302 . Moreover, the isolation power converter is also configured as an electrical isolation transformer. In operation, the isolation power converter substantially prevents any electrical spikes from damaging the switch  302  or other components in the string  220 . 
     In a second mode of operation, an operator may desire to electrically isolate the string  220  to enable maintenance to be performed on the string or for various other reasons. To manually isolate the string  220 , the operator inputs a command into the user interface  359  that instructs the processor  270  to isolate the string  220 . In this case, the processor  270  transmits a command to the isolation power converter  352  to “open” or de-energize the switch  302 . More specifically, in response to the command to isolate the string  220 , the isolation power converter  352  is instructed to cease outputting a voltage signal on the output  368 . To re-connect the string  220  to the end user, the operator inputs a command into the user interface  359  that instructs the processor  270  to reconnect the string  220  to the array. In this case, the processor  270  transmits a command to the isolation power converter  352  to “close” or energize the switch  302 . More specifically, in response to the command to re-energize the string  220 , the isolation power converter  352  is turned ON by processor  270  and a voltage signal is transmitted from the isolation power converter  352  to the switch  302  via the output  368 . In another mode of operation, the control board  350  is configured to automatically isolate the string  220  when an electrical fault is detected in the string  220  or when the power output from the string  220  decreases below a predetermined threshold. The predetermined threshold may be determined based on the power output for other strings in the array. For example, if the substring  220  is generating less than 20% of the power that the other substrings are generating, the string  220  may have a fault, and thus is automatically isolated from the array. 
     For example, during operation, the switch  302  becomes forward biased when the string is not contributing as much power to the system as other strings in the array, and hence a need may exist to automatically bypass the string. Accordingly, to automatically electrically isolate the string  220 , the control board  350  is configured to identify when the switch  302  is forward biased. 
     In the exemplary embodiment, the isolation power converter  352  is configured to determine when the FET  302  becomes forward biased by evaluating the voltage at the string. More specifically, as shown in  FIG. 16 , the isolation power converter  352  is enabled to receive an electrical input at the input  364  that represents the negative voltage at the string  220 . Moreover, the isolation power converter  352  is enabled to receive an electrical input at the input  366  that represents the positive voltage at the string  220 . During operation, the isolation power converter  352  monitors the signals received at the inputs  364  and  366  to determine when the switch  302  is forward biased. If a forward bias condition is detected, the isolation power converter  352  automatically transmits a signal to the switch  302  to open or shunt the string  220 . In the exemplary embodiment, shunting the string  220  is accomplished over a relatively long duty cycle and short detection time to facilitate maximizing the benefit of transistor shunting. If the bypass condition is not detected at a new detection cycle, the transistor  302  will not be activated and the PV module is returned to its normal working condition. Therefore, during operation, the isolation power converter  352  monitors the signals received at the inputs  364  and  366  to detect the voltage across the string  220  to determine whether the switch  302  is forward biased. 
     The control board  350  therefore enables an operator to locally or remotely input a shutdown command to electrically isolate one string or a plurality of strings. Moreover, the power utilized to operate the switches is provided by an electrically isolated power converter that receives power from a reliable power source that is mounted on the control board  350 . Optionally, the power supply  358  may be mounted on the power transfer board  32 . The control board  350  utilizes a single switch or transistor to electrically isolate each string, and therefore utilizes less power than conventional devices. 
       FIG. 17  illustrates an exemplary external system  48  that may include the junction box  14  and the control boards  200 / 300 / 350  described in  FIGS. 1-16 . In the exemplary embodiment, the system  48  represents an electrical distribution system. As discussed above, the system  48  may include, for example, a power distribution system, an electrical load, an electrical storage device, or another junction box that is coupled to another PV module. 
     In the exemplary embodiment, the system  48  includes at least two PV modules  12  and a junction box  14  coupled to each respective PV module  12 . The junction boxes  14  may include any of the control boards described herein. Moreover, the junction box  48  may include a conventional control board. The system  48  also includes, for example, a second PV module  12 , a combiner  400 , a DC switch  402 , a ground-fault circuit interrupter (GFCI)  404 , a safety isolation device  406  and an end user  408 . As shown in  FIG. 17 , the outputs from the PV modules  12  are electrically coupled to the input of the combiner  400 . The combiner  400  combines the voltages from the PV module and conveys a single power signal to the DC switch  402 . The DC switch  402  is a manually operated switch that is operable to interrupt the power signal being transmitted from the PV modules  12  to the end user  408 . The power signal is then transmitted through the GFCI  404  and the safety isolation device  406  to the end user  408 . As shown in  FIG. 17 , the two PV modules  12 , the combiner  400 , the DC switch  402 , the ground-fault circuit interrupter (GFCI)  404 , the safety isolation device  406  and the end user  408  are all electrically coupled together using a power line  410 . 
     As discussed above, PV modules, such as PV modules  12 , generate power when exposed to light even when the PV modules  12  are not coupled to an electrical grid. The power generated by the PV modules  12  may pose a safety hazard for personnel repairing the PV modules  12 . Therefore, the safety isolation device  406  is configured to provide an active safety circuit that works in conjunction with the DC switch  402 . In the exemplary embodiment, the safety isolation device  406  is located remotely from the PV modules  12 , for example, in a person&#39;s home or basement. Optionally, the safety isolation device  406  may be incorporated into the DC switch  402 . 
     In one specific embodiment, the safety isolation device  406  is configured to generate a radio frequency (RF) communication signal  414  that is transmitted wirelessly from the safety isolation device  406  to the junction box  14  to control the operation of the PV module  12 . Therefore, the safety isolation device  406  includes a transmitter  420  that transmits the wireless signal to the junction box  14 . The junction box  14  includes a transceiver  422  that receives the wireless communication. In the exemplary embodiment, the safety isolation device  406  is configured to generate a communication signal  414  that is transmitted over the power line  410  to the junction box  14  to control the operation of the PV module  12 . In operation, the communication signal  414  is overlayed onto the power signal  412 . Therefore, the communication signal  414  has a frequency or harmonic that is different than the frequency of the power signal  412  such that the communication signal  414  does not interfere with the power signal  412 . 
     In operation, the safety isolation device  406  actuates the relays shown in  FIGS. 9-14  to enable the PV module  12  to transition from an operational state, wherein the PV module  12  is delivering power to the end user  408 , to the safe state wherein the PV module  12  is electrically isolated from the end user  408 . In one mode of operation, the safety isolation device  406  automatically generates and transmits an “ON” communication signal  414  to the PV module  12 . The “ON” communication signal  414  is utilized by the junction box  14  to configure the three-stage relay  260  for normal operation, e.g. power is delivered from the PV module  12  to the end user  408 . In a second mode of operation, the “ON” signal is interrupted such that the “ON” signal is not transmitted to the PV module  12 . For example, the “ON” signal may be interrupted when an operator manually opens the DC switch  402 . The “ON” signal may be interrupted when the GFCI device  404  trips, etc. In either case, when the PV module  12  fails to receive the “ON” signal, the PV module  12  automatically isolates the PV module  12  from the system  48 . In the exemplary embodiment, the junction box  14  configures the three-stage relay  260  for safe state operation in which no power is delivered from the PV module  12  to the end user  408 . Accordingly, if the communication signal  414  is disrupted for any reason, the PV module  12  automatically realigns for safe state operation. 
     PV modules may have a variable electricity generation efficiency that is caused by manufacturing and/or installation conditions. In addition, individual PV modules may also have varying efficiency due to aging. To maximize the efficiency of the PV array it is desirable that each PV module, or group of PV modules, has a predictable and constant electrical characteristic output characteristic over its useful life. More specifically, each of the PV modules has a maximum power point (MPP) that identifies the optimal operating point of the PV module. However, when multiple PV modules are connected in series to form the PV array, if one PV module generates less power, and thus is operating under the MPP of the PV array, then the PV module generating less power determines the current flow through the PV array. Accordingly, the weakest PV module in the PV array drives the PV array such that the PV array is not generating the maximum power. 
     According to another specific embodiment of the invention, the control board  34  of junction box  14  is configured to utilize a power converter to adjust an output from the PV module to which the junction box is coupled to substantially match the MPP for the PV array. 
       FIG. 18  illustrates an exemplary external system  428  that may include the junction box  14  and the control boards  200 / 300 / 350  described in  FIGS. 1-16 . In the exemplary embodiment, the system  200  represents an electrical distribution system. The system  428  includes a plurality of PV modules  12  and a junction box  14  coupled to each respective PV module  12 . For example, the system  428  may include a PV module  430 , a PV module  432 , a PV module  434 , a PV module  436 , and a PV module  438 . Each of the PV modules  430 ,  432 ,  434 ,  436 , and  438 , has a junction box  14  coupled to it. In the exemplary embodiment, the PV modules  430 ,  432 ,  434 ,  436 , and  438  are electrically coupled together in series to form a PV module array  440 , or simply an array  440 . It should be realized that although the exemplary system  428  is shown as including five PV modules, the system  200  may include any number of PV modules electrically coupled together to form the array  440 . 
     The system  428  also includes, for example, a combiner  400 , a DC switch  402 , a ground-fault circuit interrupter (GFCI)  404 , a battery charge controller/monitor device  446 , and an inverter  448 . As shown in  FIG. 18 , the outputs from the array  440  are electrically coupled to the input of the combiner  400 . The combiner  400  combines the voltages from all the PV modules  12  and conveys a single power signal to the DC switch  402 . The DC switch  402  is a manually operated switch that is operable to interrupt the power signal being transmitted from the array  440  to an end user  450 . The power signal is then transmitted through the GFCI  404 , the battery charge controller  446 , via the inverter  448 , to the end user  450 . The end user  450  may be a business or home. Accordingly, in the exemplary embodiment, the inverter  448  converts the DC power generated by the array  440  to AC power that is usable by the end user  450 . The end user  450  may view and/or control the operation of the system  428  on a display  252 . The system  428  may also include an automatic meter reading device  454  that is mounted proximate to the home. The device  454  is configured to transmit a signal to a remote location  456  that represents the AC power consumed by the end user  450 . The device  454  may also be configured to transmit other information generated by the PV array  440  to the remote location  456 . In one embodiment, the system  428  is configured to generate a radio frequency (RF) communication signal that is transmitted wirelessly from the device  454  to remote location  456 . Therefore, the device  454  includes a transmitter  458  that transmits the wireless signal to the remote location  456 . 
       FIG. 19  is a simplified block diagram of an exemplary control board  500  that may be used with the system  428  shown in  FIG. 18 . For example, the control board  500  may be installed in any of the PV modules  430 ,  432 ,  434 ,  436 , and  438  shown in  FIG. 18 . In the exemplary embodiment, the control board  500  is substantially similar in construction to the control board  34  described above. The control board  500  is configured to be coupled to the power transfer structure or board  32  shown in  FIG. 2 . Accordingly, the control board  500  is a PCB that includes a plurality of mating connectors (not shown) that is equal to the quantity of transfer interfaces  140  installed on the transfer structure or board  32 . The combination of the transfer interfaces  140  (shown in  FIG. 2 ) and the mating connectors  160  on the control board  500  enable the outputs from the foil connectors  110 , on the power transfer board  32  (or conductive connectors on the power transfer structure), to be conveyed to the control board  500  via the transfer interfaces  140  and the mating connectors as discussed above. 
     To further explain the operation of the control board  500 , the exemplary embodiment illustrates the control board  500  being installed in the junction box  14  of the PV module  430 . However, it should be realized that each PV module in the array  440  includes an associated junction box  14  wherein the control board  500  may be installed in each respective junction box  14 . The control board  500  includes a power converter  502 , a processor  504  that is coupled to the power converter  502 , and an electrical isolation device  506  that is configured to electrically isolate the signals transmitted between the processor  504  and the array  440 . As used herein the term “processor” may include any processor or processor-based system including, for example, reduced instruction set circuits (RISC), application specific integrated circuits (ASICs), logic circuits, and any other circuit or processor capable of executing the functions described herein. The processor  504  is configured to control the operation of the control board  500 , including the power converter  502  to execute instructions and to process information received from the PV module  430  and the array  440 . The processor  504  may also include signal processing circuitry, based on a general purpose or application-specific computer, associated memory circuitry for storing programs and routines executed by the computer, as well as configuration parameters and image data, interface circuits, and so forth. 
     As shown in  FIG. 19 , the processor  504  receives the electrical output from the PV module  430 . The processor  504  identifies the MPP for the PV module  430 . For example, during operation, there is one ideal voltage/current (V/C) pair that enables the PV module  430  to generate the maximum power, e.g. the maximum power point (MPP). However, because the PV module  430  is coupled in series with other PV modules, e.g.  432 ,  434 ,  436 , and  438 , the PV module having the lowest MPP, e.g. the PV module  438 , drives the array  440 . More specifically, the array  440  generates a current that is approximately equal to the current generated by the PV module in the array  440  generating the lowest current flow. 
     For example,  FIG. 12  is a graphical illustration of exemplary MPP&#39;s that may be generated by each of the PV modules  430 ,  432 ,  434 ,  436 , and  438 . MPP 430  represents the maximum power generated by the PV module  430 , MPP 432  represents the maximum power generated by the PV module  432 , MPP 434  represents the maximum power generated by the PV module  434 , MPP 436  represents the maximum power generated by the PV module  436 , and MPP 438  represents the maximum power generated by the PV module  438 . As shown in  FIG. 12 , the PV module having the highest MPP is PV module  434 . The PV module having the lowest MPP is PV module  438 . Accordingly, the processor  504  is configured to determine the MPP for each PV module in the array  440 . Based on the determined MPP&#39;s, the processor  504  is configured to select one MPP, such as MPP 434 , that will enable the overall array  440  to operate at the maximum power. Optionally, the processor  504  may analyze the MPP&#39;s for each PV module and select an optimal MPP for the array  440  that is different than each of the MPP&#39;s for each PV module. The processor  504  is then configured to operate the power converter  502  to modify the V/C pair received from the PV module  430  to a different V/C pair that is based on the determined MPP for the array  440 . More specifically, once the processor  504  has determined the MPP for the array  440 , the V/C pair input to the power converter  502  is transformed into the V/C pair that achieves the MPP for the array. For example, assuming that the V/C pair input to the power converter  502  for PV module  430  is 30 Volts/5 Amps (overall power is 150 Watts), and the processor  504  has determined that the MPP for the system is achieved when the current flow through the array  440  is 10 Amps (e.g. the same as generated by the PV module  434 ). The processor  504  will operate the power converter  502  to modify the V/C pair input to the PV module  430  (30 Volts/5 Amps) to 15 Volts/10 Amps such that the current output from the PV module  430  is substantially equal to the current generated by the PV module  434  without modifying the power output from the PV module  430 . In this manner, the V/C pairs for each PV module in the array  440  may be modified by a respective power converter  502  to enable the array  440  to achieve overall maximum power, i.e. to enable the array  440  to operate at its MPP and maximum efficiency while also enabling each PV module in the array  440  to operate at its own MPP and maximum efficiency. The power converter  502  may be implemented as a DC-DC power supply such as a buck, a boost, or a buck-boost power supply. Additionally, the power converter  502  may be implemented as a DC-DC transformer, for example. 
     In the exemplary embodiment, the MPP for the array  440  (MPP Array ) is determined by querying each individual PV module in the array  440  to identify the MPP for each individual PV module in the array  440 . In one embodiment, the individual PV module MPP&#39;s are then used to select the MPP Array . In another embodiment, the MPP for the inverter  448  may be utilized to modify the MPP&#39;s for the individual PV modules to optimize the performance of the array  440 . For example, the impedance of the inverter  448  may be modified to achieve the MPP Array . Once the MPP Array  is selected, the power converter  502  is utilized to modify the V/C pair output from each PV module to substantially match the MPP Array . 
     The control board  500  described above, may be installed in the junction box  14  during installation of the array  440 . Optionally, the control board  500  may be integrated into the array  440  after the array  440  is installed. The control board  500  may be used in conjunction with a centralized inverter, (such as inverter  448 ) to provide communication on the ‘state of the PV module’ as needed. The PV modules discussed herein may also be modified to include safety features such as a PV module shut-off device that enables an operator to electrically disconnect a PV module from the array. Electrical surge protection from faults such as improper installation or lightning effects may also be included. 
       FIG. 21  is a simplified electrical schematic illustration of a portion of the control board  500  shown in  FIG. 18 . As discussed above, the V/C pairs for at least some of the PV modules in the array  440  are modified to achieve an overall maximum power for the array  440 . To modify the V/C pairs output from the PV modules, the control board  500  utilizes the power converter  502 . As shown in  FIG. 21 , in one embodiment, the power converter  502  may be implemented as a DC-DC converter  510 . The DC-DC converter  510  includes a switching device, such as a Field Effect Transistor (FET)  512 , an inductor  514 , and a capacitor  516 . The inductor  514  is coupled in electrical series with the FET  512  and the capacitor  516  is coupled in parallel with the FET  512 . The DC-DC converter  510  may also include a diode  518 . 
     In one mode of operation, the DC-DC converter  510  modifies the V/C pair output from the PV module (MPP 430 ) to a V/C pair (MPP Array ) that optimizes the overall power and efficiency of the array  440  as discussed above. To modify the V/C pair MPP 430 , the processor  504  first selects or identifies the MPP Array  as discussed above. The processor  504  then operates the FET  512  to convert the V/C pair MPP 430  to the V/C pair MPP Array . More specifically, the processor  504  transmits a signal, at a predetermined frequency, to the FET  512  that causes the FET  512  to oscillate at the predetermined frequency. Oscillating the FET  512  at the predetermined frequency causes the voltage of the V/C pair MPP 430  to be transformed to the selected voltage of the V/C pair MPP Array . Moreover, excess energy is stored in the inductor  514  and the capacitor  516 . In the exemplary embodiment, the FET  512  may be oscillated at a plurality of frequencies, wherein each frequency corresponds to a different voltage being output from the DC-DC converter  510 . 
     In the exemplary embodiment, the DC-DC converter  510  is also operable to electrically isolate the PV module  430  from the array  440 . Such electrical isolation may be required, for example, when an electrical fault has occurred in the PV module  430 . To electrically isolate the PV module  430  from the array  440 , the processor  504  is configured to turn off the FET  512 . In this case, when the FET  512  does not receive an appropriate signal from the processor  504 , the FET  512  is off and defaults to an “open” position. As shown in  FIG. 21 , when the FET  512  is in the open position, current discharged from the PV module  430  is channeled across the top rail through the inductor  514 , through the FET  512  and back through the bottom rail to the PV module  430 . As such, when the FET  512  is in the open position, current is channeled in a loop within the control board  500  and is not supplied to the array  440 . Accordingly, in one embodiment, the DC-DC converter  510  is also configured to function as an isolation transformer between the PV module  430  and the array  440  to fully electrically isolate the PV module  430  from the array  440 . Specifically, once the processor  504  is configured to turn on the FET  512 , the DC-DC converter  510  will not allow power to be transmitted from the PV module  430  to the array  440 , because when the DC-DC converter  510  is operating as an isolation transformer, only AC power is enabled to be transmitted through the isolation transformer. 
       FIG. 22  is another simplified electrical schematic illustration of a portion of the control board  500  shown in  FIG. 18 . As shown in  FIG. 22 , in one embodiment, the power converter  502  may be implemented as a DC-DC converter  520 . The DC-DC converter  520  includes a first switching device, such as FET  522  and a second switching device, such as FET  524 . The DC-DC converter  520  also includes a DC-DC driver  526  that is electrically coupled to, and operates, the FETs  522  and  524  based on a signal received from the processor  504 . The DC-DC converter  520  also includes an isolation transformer  528  that is coupled to the outputs of each respective FET, e.g. FETs  522  and  524 . 
     In one mode of operation, the DC-DC converter  520  is configured to modify the V/C pair output from the PV module (MPP 430 ) to a V/C pair (MPP Array ) that optimizes the overall power and efficiency of the array  440  as discussed above. To modify the V/C pair MPP 430 , the processor  504  first selects or identifies the MPP Array  as discussed above. The processor  504  then transmits a signal to the driver  526 . The driver  526  includes electrical circuitry to enable the signal received from the processor  504  to be converted to a pair of signals. Each signal in the pair of signals is transmitted to a respective FET to operate the FET. More specifically, the processor  504  transmits a signal to the driver  526 . 
     During operation, when the processor  504  determines that power should be supplied from the PV module  430  to the array  440 , the driver  526  transmits a signal at the predetermined frequency to the FETs  522  and  524  that causes the FETs  522  and  524  to oscillate at the predetermined frequency. Oscillating the FETs  522  and  524  at the predetermined frequency causes the V/C pair MPP 430  to be transformed to the selected V/C pair MPP Array . Moreover, excess energy is stored in the inductors and the capacitors shown in  FIG. 22 . The FETs  522  and  524  may be oscillated at a plurality of frequencies, wherein each frequency corresponds to a different voltage being output from the DC-DC converter  520 . 
     Additionally, the oscillation of the FET&#39;s at the predetermined frequency causes the voltage signal output from the FET&#39;s to be converted to an A/C signal which is then transmitted through the transformer  528 . More specifically, as shown in  FIG. 22 , when the FETs  522  and  524  are energized, an AC signal is transmitted from the FET  522  through the primary winding  530  of the transformer  528  and discharged through the FET  524 . The secondary winding  532  then transmits the electrical signal generated by the windings to the array  440 . 
     In the exemplary embodiment, the DC-DC converter  520  is also operable to electrically isolate the PV module  430  from the array  440 . Such electrical isolation may be required, for example, when an electrical fault has occurred in the PV module  430 . To electrically isolate the PV module  430  from the array  440 , the processor  504  is configured to cease transmitting a signal to the driver  526 . The driver  526  then ceases to transmit a corresponding signal to the FETs  522  and  524 . In this case, when either the FET  522  or the FET  524  does not receive a signal from the processor  504 , the FETs  522  and  524  are off and default to an “open” position. As shown in  FIG. 22 , when either the FET  522  or the FET  524  is in the open position, current discharged from the PV module  430  is channeled through the FET  522 . However, because the FET&#39;s  522  and  524  are open, the output from the FETs  522  is a DC voltage signal. Thus, the isolation transformer  528  is unable to generate an output based on a DC voltage input, thus effectively isolating the PV module  430  from the array  440 . 
     The control boards described herein utilize transformer-based DC-DC circuitry to implement efficiency improvements on the PV modules or a sub-set of the PV modules. The control boards also provide an effective device for electrically isolating the PV module from the array. It should be realized that a plurality of electrical designs to implement a DC-DC converter may be utilized, and that the embodiments described herein are exemplary embodiments. Specifically, the junction box described herein includes a control board that enables the control board to electrically isolate the PV module from the array. Moreover, the control boards optimize the output from each PV module to optimize the power generated, and the efficiency of, the array. 
     While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. The application is, therefore, intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means—plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.