Abstract:
A junction box is affixed to, and electrically coupled with, a solar panel. The junction box is configured to releaseably engage and disengage accessory modules, thereby allowing accessory modules to be replaced or exchanged easily. Accessory modules are electrically coupled with other accessory modules in the solar panel string. The furthest downstream accessory module is connected to a wire harness, which is connected to a central combiner box.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of, and claims the benefit of, U.S. application Ser. No. 13/761,532, having a filing date of Feb. 7, 2013. 
    
    
     BACKGROUND 
     (1) Field 
     The present invention relates generally to electrical control systems for use in the solar industry and, more particularly, to junction boxes that facilitate “plug and play” functionality of solar energy accessory modules. 
     (2) Related Art 
     The invention discussed herein can be used with connectors disclosed in U.S. patent application Ser. No. 12/502,395, pertaining to “Low Leakage Electrical Joints and Wire Harnesses, and Method of Making the Same”, that was filed on Jul. 14, 2009, and issued on Dec. 10, 2013 as U.S. Pat. No. 8,604,342 B2, which is hereby incorporated by reference. 
     Due to technological advances, increased costs of non-renewable resources, and governmental incentives, solar energy can now be an economically advantageous endeavor. Accordingly, interest in solar energy has surged, and innovators are constantly developing new systems and components to optimize energy collection because variables such as inconsistent sunlight, breakage and malfunction outages in the solar field, and other fluctuations greatly affect the operating environment. 
     Considerable progress in optimization has been achieved by the development and refinement of various “accessory modules”. In short, accessory modules are electrical components added onto conventional junction boxes to perform functions such as lessening peaks and valleys in energy generation, Maximum Power Point Tracking (“MPPT”), and to allow for direct AC conversion, including that achieved by micro-inverters. To achieve this, one junction box is outfitted with one accessory module, so the solar panels associated with that specific junction box are mediated by that specific accessory module. 
     While employing accessory modules is definitely an improvement over not using accessory modules, the one-module-per-group-of-panels arrangement does not permit optimization of the individual panels. This is undesirable because individual panels in a group may exist in different microenvironments. For example, one panel might be partially shaded while another panel is not. Accordingly, the optimization of individual panels would be most beneficial. 
     Optimizing individual panels, however, has been impractical or undesirable up until now. Specifically, coupling a panel to an accessory module requires affixing and hard wiring them together. As a result, when a panel or accessory module is damaged, destroyed, or otherwise quits working properly, the panel and accessory module are more-or-less permanently stuck together, and the entire assembly must be replaced. Alternatively, extensive time and labor is expended to separate the good hardware from the bad. Moreover, if it is desirable to swap out one accessory module for another (for example due to seasonal sunlight changes) one must swap the entire panel. This makes the optimization of individual panels impractical. 
     In view of the aforementioned limitations, it is desirable to have a device that allows an individual solar panel to be easily, expeditiously and reversibly outfitted with an accessory module. 
     Thus, there remains a need for a new and improved solar panel junction box capable of integrating with a variety of accessory modules, and the method of using this junction box. 
     SUMMARY OF THE INVENTIONS 
     The present invention is directed to a universal junction box that is affixed to a solar panel and replaces the conventional junction box and downstream accessory module box. The junction box is configured to releaseably engage and disengage accessory modules which employ a standard engagement interface, thereby facilitating the replacement of one accessory module for another, for whatever reason, without having to replace or move the associated panel. 
     The junction box is electrically connected to the associated solar panel by the panel&#39;s electrical ribbon. Individual panels in a string are connected to each other in series only through wire connectors of the accessory modules. The furthest downstream accessory module is connected to a wire harness, which is connected to a central combiner box. 
     One aspect of the present inventions is to provide a device that can be substantially permanently affixed to a solar panel. 
     Another aspect is that this device releaseably engages and disengages an accessory module, thereby allowing accessory modules to be replaced and changed with minimal effort, time, danger or damage. 
     Another aspect is that this device is compatible with preexisting accessory module interfaces. 
     Another aspect is that this device provides functionality beyond a simple docking station, for example by acting as a junction box. 
     Another aspect is that this device is configured to quickly and easily interconnect with other panels in a string. Another aspect is that this device is compatible with preexisting connectors, plugs, implements and accessories. 
     Another aspect is that this device can be used for retrofitting existing panels, or can be coupled with newly manufactured panels. 
     Another aspect is that this device is safe, cost effective, electrically efficient and not labor or capital intensive to manufacture, deliver or install. 
     These and other aspects of the present inventions will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  schematically represents a string of solar panel control systems; 
         FIG. 2  is a perspective view of a junction box; 
         FIG. 3  is a plan view of a junction box; 
         FIG. 4  is a side view of a junction box; 
         FIG. 5  is a plan view of a junction box with the lids removed to show structures beneath; 
         FIG. 6  is a cross-sectional plan view of a junction box, taken along B-B of  FIG. 4 ; 
         FIG. 7  is an end view of a junction box; 
         FIG. 8  is a cross-sectional side view of a junction box, taken along A-A of  FIG. 3 ; 
         FIG. 9  represents a bottom view of an accessory module schematically representing where an input could be plugged in; 
         FIG. 10  schematically represents how an accessory module is engaged with a junction box, with the raised strips of the accessory module shown in phantom; and 
         FIG. 11  schematically represents an accessory module engaged with a junction box, with certain accessory module structures shown in phantom. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description, like reference characters designate like or corresponding parts throughout the several views. 
     The following reference characters apply: 
       10 —Junction box 
       13 —Engagement platform 
       15 —Base assembly 
       16 —Air vent 
       17 —Groove 
       18 —Recess 
       19 —Securing rib 
       20 —Socket terminal assembly 
       22 —Front surface 
       23 —Back surface 
       27 —Ribbon terminals 
       28 —Ribbon 
       30 —Removable lid 
       35 —Diode cover 
       40 —Female module plug 
       41 —O-ring 
       42 —Female Module terminal 
       45 —Diode assembly module 
       46 —Diode 
       60 —Solar array 
       65 —String 
       70 —Solar panel 
       80 —Wire harness 
       90 —Accessory Module 
       92 —Male module plug 
       94 —Clipping assembly 
       95 —Alignment ribs 
       96 —Input 
       97 —Output 
       98 —Wire connector 
       99 —Wire plug 
       100 —Solar panel control system 
     Referring now to the drawings, it will be understood that the illustrations describe a preferred embodiment of the invention, but are not intended to limit the inventions thereto. 
     An overview of solar array  60  is schematically depicted in  FIG. 1 , which preferably includes between 6 and 8 solar panels  70  in string  65 , each solar panel  70  including one junction box  10 , with each junction box  10  engaged to and in communication with one accessory module  90 . The resulting assembly of accessory module  90 /junction box/solar panel  70  is solar panel control system  100 . 
     Each accessory module  90  is electrically connected to another accessory module  90 . Solar panels  70  are those conventionally used in small- and industrial scale solar energy systems, with an example of a suitable panel being E237 from SunPower Corporation of San Jose, Calif. 
     The most downstream junction box  10  (bottom left) in string  65  is connected by wire harness  80  to “COMBINER”. Wire harness  80  is preferably the device disclosed in U.S. patent application Ser. No. 12/502,395, filed on Jul. 14, 2009, issued on Dec. 10, 2013 as U.S. Pat. No. 8,604,342 B2, and which is incorporated herein.  FIG. 1  depicts wire harness  80  accommodating 6 strings  65  (one string  65  plus 5 “bolts” representing other strings) but between 3 and 64 strings can be accommodated by wire harness  80 . All strings  65  (and associated components such as solar panels  70 ) in one wire harness  80  collectively form solar array  60 . 
     Downstream from COMBINER BOX is FUSE BOX, INVERTER and SWITCH YARD. As would be understood by one of ordinary skill, the combiner would actually accommodate multiple wire harnesses  80 , the fuse box would actually accommodate multiple combiners, the inverter would actually accommodate multiple fuse boxes, and the switch yard would actually accommodate multiple inverters. However, redundant assemblies have been omitted for simplicity. The person of ordinary skill would also understand that the depiction merely represents some major components in one possible system. 
     One junction box  10  is affixed to each solar panel  70 , preferably by an adhesive such as PV  804  from Dow Corning of Midland, Mich., although other adhesives, or standard methods of attaching would be suitable. Back surface  23  (shown in  FIG. 4 ) is adhered to solar panel  70 . While  FIG. 1  schematically depicts junction boxes  10  on the side of solar panels  70 , it is possible to affix junction box  10  in other locations, preferably on solar panel  70  itself, so long as front surface  22  ( FIG. 4 ) is accessible to permit engagement of accessory modules  90 , and to permit connection of junction box  10  to solar panel  70  by ribbon  28 .  FIG. 1  depicts six solar panels  70  of string  65  in series, but it would also be possible to orient them in parallel. 
     Referring now to  FIG. 2 , junction box  10  is constructed on base assembly  15  and can be conceptualized as having the electrical “brains” in the upper half, and the physical “module interface” in the lower half. Externally on the upper half is removable lid  30  which, as the name implies, is removable. Externally below removable lid  30  is diode cover  35 , which is not removable. Removable lid  30  and diode cover  35  protect the electrical connections underneath, which are integral to base assembly  15 . As used herein, “integral electrical connections” and like terms refer to the orientation of electrical components within base assembly  15  wherein base assembly  15  physically receives and secures the electrical components, versus providing a generic housing wherein electrical components and fasteners are assembled and secured therein. 
     More specifically, the integral electrical connections beneath removable lid  30  are ribbon terminals  27  ( FIGS. 5 and 6 ) which attach to ribbons  28  of solar panel  70 , as shown in  FIG. 1 . The ribbons in the solar panel are an electromechanical means of providing power from the solar cells to the junction box ribbon terminals. Ribbon terminals  27  provide the electrical path from panel  70  into junction box  10 . 
     The integral electrical connections beneath diode cover  35  include diode printed circuit board assembly module  45  ( FIGS. 5 and 8 ), including diodes  46  ( FIG. 8 ). The function of diode assembly module  45  provides the electrical connection between ribbon terminals  27  and output terminal  20  while providing the bypass and reverse leakage functionality required to protect the solar panel. 
     As best shown in  FIG. 5 , socket assembly  20  is electrically connected to diode assembly module  45 . Socket assembly  20  includes O-ring  41  ( FIG. 3 ) and male module plug  40 , neither of which are concealed by diode cover  35 , as shown in  FIGS. 2 and 3 . As shown in cross section in  FIG. 6 , module terminal  42  is within male module plug  40  Male module plug  40  connects with female module plug  92  of accessory module  90 , as shown in  FIG. 10 . 
     Accessory module  90  can be a variety of types used in the solar energy industry. An example of a power electronics type accessory module is a microinverter from Solantro Semiconductor of Ottawa, Ontario, Canada. An example of a supervisory or control type accessory module is an MPPT SPM1258A-S from Solar Power Technologies of Austin, Texas and/or a boost controller STG-MLM2-4 from Tigo Energy of Los Gatos, Calif. An example of a standard accessory module is STG-MLM-2 from Shoals Technologies Group of Portland, Tenn., which essentially acts as a place holder but does not perform an accessory module function. This invention contemplates using modules which are not yet designed or known, for example arc fault detection, as well as those in development and commercially available. However, in order to properly interface with junction box  10 , accessory module  90  would have the universal orientation shown in  FIGS. 9 and 10 , including three clipping assemblies  94 , and two female module plugs  92 . This unique interface between the junction box and accessory module allows interchangeability of a limitless variety of modules. 
     Returning to junction box  10  ( FIGS. 2 and 7 ), on either side of each male module plug  40  is securing rib  19  which mates with clipping assembly  94  of module  90  ( FIG. 9 ) when module  90  is slid into position on junction box  10 , as shown best in  FIG. 10 . While clipping assembly  94  and securing rib  19  are preferred, other mechanisms for fastening module  90  into position on junction box  10  are also possible. 
     Clipping assembly  94  and securing rib  19  assist in holding module  90  and junction box  10  together when engaged. In addition, other structures are involved with alignment and securing. As shown in  FIG. 2 , engagement platform  13  defines grooves  17  that receive corresponding alignment ribs  95  on module  90 , shown in  FIG. 9 . As used herein, “engagement platform” shall refer to the general region of junction box  10  that includes grooves  17 , recess  18 , and surrounding (unnumbered) planar surface. In operation, a user aligns alignment ribs  95  of accessory module  90  with grooves  17  of junction box  10 , and slides accessory module  90  until female module plug  92  engages with male module plug  40 . The pre-engagement alignment is represented in  FIG. 10  and engaged orientation is depicted in  FIG. 11 , with certain structures shown in phantom. Although not obvious from the drawings, grooves  17  are tapered going inward, thereby further securing junction box  10  and accessory module  90  together. It should be noted that junction box  10  and accessory module  90 , when engaged, are releaseably engaged. As used herein “releaseably engaged” and similar terms refer to an engagement between parts wherein a user can apply reasonable physical force, with or without the necessary use of tools, to engage the parts, and reasonable physical force, with the use of tools, to disengage the parts, with such engagement and disengagement not likely to damage the parts, and with unintentional engagement and disengagement unlikely to occur in regular use. Recess  18  provides additional air circulation for engaged module  90  in order to reduce hot spots on the solar panel. 
       FIG. 11  shows an accessory module engaged with junction box  10 . In this orientation, input  96 , with wire connector  98  and wire plug  99 , is shown on the bottom, and output  97 , with wire connector  98  and wire plug  99 , is shown on the top. However, it should be noted that accessory modules  90  come in a variety of different sizes, and have different functions, and the specific location of input  96  and output  97  is unimportant so long as it can properly interface with junction box  10 . Preferably wire plug  99  will be at the distal (relative to accessory module  90 ) end of wire connector  98  for output  97 , and proximal end of wire connector  98  for input  96 . In this orientation the proximal end of wire connector  98  is “hard wired” into accessory module  90  for output  97 . Alternatively, it is possible to employ wire plug  99  and wire connectors  98  at both ends of wire connector  96 . Also, it is possible to employ a wire with a wire plug  99  or wire connector  98  and a bulkhead connector molded into the accessory module. Also, it is possible to have the input  96  and output  97  both be molded in connectors allowing the customer to control the wire length. Preferably wire plug  99  is MC4 from Multi-Contact of Windsor, Calif. 
     In use, one could either purchase solar panel  70  with junction box  10  already mounted, or retrofit existing solar panel  70  by affixing junction box  10 . With junction box  10  in position, module  90  is engaged with engagement platform of junction box  10 . The same is performed for other solar panels  70  in string  65 . The specific modules  90  selected for each panel  70  depends on the particular circumstances. For example, a panel which is often in the shade might benefit from a boost controller, part number STG-MLM2-4, from Tigo Energy, while a panel that requires monitoring or switching capability might benefit from a MPPT accessory module, part number SPM1258A-S from Solar Power Technologies. Furthermore, a panel that requires AC output might benefit from a microinverter accessory module from Solantro Semiconductor. The resulting module type, or combination of module types, should be selected to optimize the overall productivity of the system with respect to energy generation, cost savings, safety, and so forth. Solar panels  70  are grouped into string  65  by connecting output  97  of a downstream accessory module  90  to input  96  of immediately upstream accessory module. Strings are connected at most downstream point to wire harness  80 . All the strings connected to one wire harness  80  are collectively solar array  60 . 
     Accessory modules  90  are interchangeable by disengaging accessory module  90  from junction box  10  (which is affixed to solar panel  70 ), and engaging a different accessory module. As used herein “interchangeable solar panel control system” refers to solar panel control system  100  with this functionality. 
     Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. By way of example, if one accessory module would suffice for all panels in a string, all panels except one could employ “standard accessory modules”. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.