Terminal box for a solar battery module and a method for producing such a terminal box

A terminal box for a solar battery module is provided with a plurality of terminal plates (30) juxtaposed in a box main body (10) and connectable with positive and negative electrodes of the solar battery module, cables (90) for external connection connectable with the terminal plates (30), a conductor piece (50) connected with one of two corresponding terminal plates (30) and extending from this one terminal plate toward the other, and a bear chip diode (70) held between the conductor piece (50) and the other terminal plate (30) to be connected with both. The conductor piece (50) is connectable with a P-area (72) of the bear chip diode (70) and the other terminal plate (30) is connectable with an N-area (71) of the bear chip diode (70).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a terminal box for a solar battery module and a method for producing such a terminal box.

2. Description of the Related Art

A solar energy generation system supplies direct-current electricity from a solar battery panel on the roof of a building to electric equipment via an inverter or the like. The solar battery panel has solar battery modules, and electrodes of the solar battery modules are connected in series or in parallel via terminal boxes.

Japanese Patent Publication No. 3498945 discloses a known terminal box that has terminal plates juxtaposed in a box. Ends of the terminal plates at one side are connectable with positive and negative electrodes drawn out from the underside of the solar battery module. The other ends of the terminal plates are connectable with cables for external connection. Bypass diodes span between adjacent terminal plates. The bypass diode shorts an inverse current at the time of an inverse load from one cable for external connection to the other. The bypass diode has a chip-shaped diode functioning portion and two conductor pieces connected with the diode functioning portion while holding the diode functioning portion therebetween. The conductor pieces have contacts and the diode functioning portion is between overlapping portions of the contacts. The conductor pieces extend in opposite directions from the contacts, and have extending ends connected to the corresponding terminal plates. The contacts of the conductor pieces are supported from below by the bottom surface of the box or distanced therefrom between the adjacent terminal plates.

Heat generated by the diode functioning portion should be discharged toward the terminal plates via the respective conductor pieces. However, heat remains in the above-described diode functioning portion and the bypassing function of the diode functioning portion can be impaired.

The invention was developed in view of the above problem and an object thereof is to improve heat discharging characteristics.

SUMMARY OF THE INVENTION

The invention relates to a terminal box for a solar battery module. The terminal box has a box main body, and terminal plates are arranged in the box main body. The terminal plates are connectable with positive and negative electrodes of the solar battery module and are connectable with cables for external connection. A conductor piece extends from one terminal plate toward another, and a rectifying-device main body is held between the conductor piece and the other terminal plate and is connected directly with both.

The rectifying-device main body is held directly between the conductor piece and the terminal plate. Thus, heat generated by the rectifying-device main body can be discharged directly and quickly towards the terminal plates. Heat discharging characteristics are better as compared to a case where the rectifying-device main body is held between the conductor pieces.

The rectifying-device main body preferably is provided for bypass at the time of an inverse load.

The terminal plates preferably are juxtaposed in the box main body.

The rectifying-device main body preferably includes a bear chip diode, a mesa chip diode or surface etched diode. The conductor piece is connectable with a P-area of the bear chip diode and the other terminal plate is connectable with an N-area of the bear chip diode. Thus, a large joined area is ensured between the terminal plate and the bear chip diode, and the heat generated by the bear chip diode can be discharged efficiently from the N-area to the terminal plate.

The conductor piece preferably has a terminal-side contact connected with one of the adjacent terminal plates and a device-side contact extending from the terminal-side contact towards the other terminal plate.

The device-side contact preferably is placed on the other terminal plate while holding the bear chip diode between it and the other terminal plate.

The conductor piece preferably has a stress relieving portion between the device-side contact and the terminal-side contact to absorb a stress acting thereon and/or on adjacent elements.

Adjacent terminal plates excluding those to be connected with the cables preferably are coupled temporarily to each other via a coupling portion at one end. At least one of these terminal plates preferably has no contact with the lead of the solar battery module, is shorter than the other terminal plate and/or has the leading end thereof at least partly surrounded by partition walls.

The invention also relates to a method for producing a terminal box for a solar battery module. The method comprises applying solder paste onto parts of at least two terminal plates. The method then places a rectifying device main body, preferably a bear chip diode, and a conductor piece on the corresponding terminal plates so that the rectifying device main body is between the one terminal plate and the conductor piece. The method then proceeds by heating and melting the solder paste. The molten solder paste then is solidified to solder-weld the rectifying device main body and the conductor piece to the corresponding terminal plates.

The method for producing the terminal box for a solar battery module may include coupling two terminal plates by a bridging portion. The method then includes applying solder paste onto the terminal plates. The method proceeds by placing a rectifying device main body and a conductor piece on the solder paste of the corresponding terminal plates so that the rectifying device main body is between the one terminal plate and the conductor piece. The method continues by heating the solder paste to melt the solder paste and solidifying the molten solder paste, thereby solder-welding the rectifying device main body and the conductor piece to the corresponding terminal plates. The method then includes interrupting the bridging portion after the terminal plates are assembled into the box main body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A terminal box for a solar battery module according to the invention is identified by the letter B inFIGS. 1 to 4. The terminal box B is mounted on the underside of a solar battery module (not shown) having solar battery cells connected in series arranged on the outer surface thereof.

The terminal box B has a box main body10made e.g. of a synthetic resin and defines a box with an open top. The term top is used herein to provide a convenient frame of reference, but does not imply a required gravitational orientation. The box main body10has a substantially rectangular base plate11and a side plate12projects up from the outer peripheral edge of the base plate11to surround at least part of the base plate11. Insulating resin is filled into the inside of the box main body10, and a cover (not shown) is mountable on the box main body10from above. Terminal plates30are arranged substantially side by side on the base plate11and partition walls13stand up at specified positions of the base plate11to partition the adjacent terminal plates30. The base plate11has four substantially rectangular openings14, and the leading ends of the corresponding terminal plates30face the respective openings14. Leads (not shown) connected with positive and negative electrodes of the solar battery module are introduced through the respective openings14of the base plate11and are connectable with the leading ends of the terminal plates30, e.g. by soldering, (ultrasonic) welding, press-fitting, clamping or the like.

Positioning projections15project from the upper surface of the base plate11and are engageable with positioning holes31of the terminal plates30. Two resiliently deformable locking pieces16project at opposite outer sides of each positioning projection15. The locking pieces16deform laterally in the process of mounting the terminal plate30to widen the spacing therebetween. The locking pieces16restore as the terminal plate30is mounted properly to press the opposite lateral edges of the terminal plate30from above, thereby preventing the terminal plate30from moving up and away from the base plate11.

Notches17are formed at the substantially opposite ends of the upper edge of the side plate12. Cables90for external connection are fit into the notches17from above and cable pressing members20fix the cables90into the notches17. The fitted cable pressing members20are unitarily continuous with the side plate12. The partition walls13extend substantially along the outer shapes of the terminal plates30, and the terminal plates30are mounted and guided by the partition walls13. Further, insulating resin is fill into inner spaces defined by the partition walls13above the terminal plates30.

The terminal plates30are formed by cutting or stamping an electrically conductive metal plate into strips. The terminal plates30at opposite ends of the base plate11are connected with the corresponding cables90for external connection. An insulation coating is stripped at an end of each cable90to expose a core91, and a barrel32at an end of the terminal plate30is crimped, bent or folded into connection to connect the cable90and the terminal plate30. An extending end of the cable90is connected with a connector portion (not shown).

The terminal plates30that are not connected with the cables90are arranged in pairs30A,30B. The terminal plates30A,30B in each such pair are coupled unitarily to each other via a coupling33at one end. The terminal plate30A is shorter than the terminal plate30B. Additionally, the terminal plate30A does not contact the lead of the solar battery module and at least part of the leading end of the terminal plate30A is surrounded by the partition walls13. Thus, the terminal plate30A detours from the other terminal plate30without being directly involved in connection with the mating side, and a creepage distance for letting heat generated by the bear chip diode70escape is lengthened by this detour to improve a heat discharging effect.

Attachments34bulge out sideways at opposite lateral edges of each terminal plate30and edges of the attachments34at the projecting ends are opposed to each other between the adjacent terminal plates30. The conductor pieces50thinner than the terminal plates30span between the adjacent terminal plates30. In the shown case, three conductor pieces50are arranged in series while crossing the respective terminal plates30.

As shown inFIGS. 2 to 4, each conductor piece50has a terminal-side contact51connected with one of the adjacent terminal plates30, e.g. by solder welding, soldering, ultrasonic welding, gluing with a conductive glue or the like. A device-side contact52extends from the terminal-side contact portion51towards the other terminal plate30and is placeable on the other terminal plate30while holding the bear chip diode70between the adjacent terminal plates30. A stress relieving portion53is arranged between the device-side contact52and the terminal-side contact51to absorb stress resulting from welding or the like.

As shown inFIG. 3, the bear chip diode70has a multilayer structure that includes an anode electrode, i.e. a P-area72, placed over a cathode electrode, i.e. an N-area71, to form a substantially trapezoidal or troncoconical shape and a glass film73is provided around this multilayer structure. The device-side contact52of the conductor piece50is connectable with the P-area72of the bear chip diode70and the terminal plate30is connectable with the N-area71of the bear chip diode70.

The terminal-side contact51is superimposed on the one terminal plate30along its plane direction (i.e. a direction substantially normal to the plane), and is welded to this superimposed portion. The stress relieving portion53includes narrow strip pieces53A extending substantially oblique to the longitudinal direction of the conductor piece50. Thus, the conductor piece50can expand and contract along the longitudinal direction of the conductor piece50by the deformation of the narrow strip pieces53A. The narrow strip pieces53A are spaced apart by a specified distance and have substantially the same width over substantially their entire lengths. The device-side contact52is substantially continuous with the stress relieving portion53via a rectangular constriction54, and has the lower surface connected with the P-area72of the bear chip diode70by soldering or welding. The attachment portion34of the other terminal plate30faces this device-side contact52with the bear chip diode70sandwiched therebetween. The bear chip diode70is placed thereon and connected by soldering or welding.

Either of two methods can be adopted to connect the bear chip diodes70and the conductor pieces50with the terminal plates30. A first method mounts the terminal plates30on the base plate11and solder paste is applied in specified areas on the terminal plates30. The bear chip diodes70and the conductor pieces50then are placed on the solder paste on the corresponding terminal plates30and solder-welded is applied to the corresponding terminal plates30by heating the solder paste with a soldering iron or by resistance welding to melt the solder paste and then solidifying the molten solder paste.

A second method integrally or unitarily couples the adjacent terminal plates30to each other by bridging portions35as shown inFIG. 5prior to the mounting of the terminal plates30on the base plate11. These chained terminal plates30are positioned and set in a carbon jig and solder paste is applied in specified areas on the terminal plates30. The bear chip diodes70and the conductor pieces50then are placed on the solder paste of the corresponding terminal plates30and are solder-welded to the corresponding terminal plates30by heating the solder paste in a reflow apparatus to melt the solder paste and then solidifying the molten solder paste. According to this second method, the bridging portions35are separated or cut off after the terminal plates30are mounted on the base plate11.

The terminal plates30are positioned on the base plate11by inserting the positioning projections15projecting from the base plate11into the positioning holes31of the terminal plates30. Resilient locking pieces16engage the terminal plates30to prevent the terminal plates30from moving up and away from the base plate11. The barrels32of the terminal plates30are crimped, bent or folded into connection with the cores91exposed at the ends of the cables90to connect the terminal plates30and the cables90. The cable pressing members20are mounted to cover the cables90from above or from outside. Thus, the cables90are fixed and loose movements are prevented.

The box main body10is mounted to the underside of the solar battery module preferably using an adhesive double coated tape or is secured thereto by bolts. Leads connected with the electrodes of the solar battery module are drawn through the respective openings14of the base plate11and into the box main body10during the mounting process and are connected with the leading ends of the terminal plates30by soldering, welding, press-fitting or the like. Insulating resin, such as a silicone, then is filled into the inner spaces between the partition walls13in the box main body10, and the cover is mounted to close the box main body10. The crimp-connected parts, the solder-connected parts, and similarly connected parts are sealed airtight by the insulating resin.

As described above, the heat generated by the bear chip diodes70can be discharged directly and quickly towards the terminal plates30because the bear chip diodes70are held between the conductor pieces50and the terminal plates30either in direct surface contact or in contact via a thin connection made e.g. by soldering paste or other connecting element. Thus, heat-discharging characteristics are better as compared to a case where the bear chip diodes are held between the conductor pieces50. Accordingly, the bypassing function of the bypass diode constructed by the bear chip diode70and the conductor piece50can be displayed over a long time.

The conductor piece50connects the P-area72of the bear chip diode70and the terminal plate30is connectable with the N-area71of the bear chip diode70. Thus, a large joined area is ensured between the terminal plate30and the bear chip diode70and heat generated by the bear chip diode70is discharged efficiently to the terminal plate30from the N-area71.

The invention is not limited to the above described and illustrated embodiment. For example, the following embodiments are embraced by the scope of the invention as defined by the claims. Other changes can be made without departing from the scope of the invention as defined by the claims.

Although several terminal plates are juxtaposed in the box main body in the foregoing embodiment, only two terminal plates may be arranged in the box main body according to the invention.

Although the conductor pieces and the terminal plates are connected by solder welding in the foregoing embodiment, they may be connected by resistance welding or ultrasonic welding or by any other connecting methods according to the present invention.