Solar energy wire harness with in-line fuses

A wire harness connects multiple solar panel junction boxes to a recombiner box. The wire harness includes in-line fuse assemblies, with optional blocking diodes, so each string of solar panels is associated with one fuse. In the event of a blown fuse, only one upstream solar panel string is affected. Entire wire harnesses and/or individual in-line fuse assemblies can be easily swapped out, thereby decreasing the time and expense of troubleshooting and repairing.

BACKGROUND

The present invention relates generally to components used in the solar energy industry and, more particularly, to wire harnesses with in-line fuses for electrically coupling solar panel junction boxes to recombiner boxes.

(2) Related Art

The problems associated with the world's dependence on non-renewable resources have resulted in increased attention to so-called alternative energy, such as solar and wind power. As a result, small-scale production of alternative energy, for example by installing residential solar heaters or wind turbines, has become more popular. While these actions may provide psychological and possible long-term financial benefits, the actual contribution to the power grid is minimal. Permanent and significant changes necessitate the implementation of alternative energy generation on a large-scale utility basis.

Utility scale production of solar energy, however, is often considered financially imprudent given the high cost of materials, know-how, and labor. For example, conventionally wiring solar panels typically requires a qualified electrician to measure, cut, connect and crimp wires on site, by hand, between each individual solar panel's junction box and the combiner box that conventionally contains the fuses. In addition, the resulting combiner box is a confusing array of electronics that often requires extensive labor and expense for troubleshooting and repairing. Also, a blown fuse will result in the shut down of an array of solar panels, thus decreasing the productivity of the system.

Accordingly, the interests of being environmentally responsible often conflict with the financial realities of building and maintaining a solar energy plant.

Thus, there remains a need for components for use in solar plants that decrease the materials, know-how and/or labor associated with building and maintaining the electrical infrastructure.

There also remains a need for components for use in solar plants that are easily identified as problematic, and replaced, in the event of a failure.

A need also exists for components that prevent the loss of energy in the event of a failure.

Moreover, a need exists for a solar wiring architecture which does not shut down more solar panels than necessary in the event of a failure.

Ideally, these components are relatively simple, safe and inexpensive to manufacture, transport and use.

Methods of using the aforementioned components, and creating the aforementioned architecture, are also needed.

SUMMARY OF THE INVENTIONS

The present inventions are directed to wire harnesses for electrically connecting multiple solar panel junction boxes to a recombiner box. The wire harnesses are capable of handling high voltage, low current power, and can be configured in a variety of ways. Each branch of a wire harnesses connects to the junction box of a solar panel, with each of the branches including an in-line fuse assembly. The multiple branches of the wire harness feed into a common wire harness trunk. The terminal end of each branch and trunk includes a positive or negative connector, to facilitate easy installation or replacement by mating with a corresponding connector on a junction box or recombiner box. The in-line fuse assembly may include a variety of fuse types, such as midget fuses and/or 1000V fuses, and may optionally include a blocking diode. The in-line fuse assembly may also include connectors, so that individual fuses may be swapped out in the event a fuse is blown, versus replacing the entire wire harness. One of the advantages of this invention over conventional wiring is that the fuses are not in the combiner box. Accordingly, when a fuse is blown, only one solar array is affected. When a fuse of a conventional combiner box is blown, all panels downstream from that fuse are affected.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, like reference characters designate like or corresponding parts throughout the several views. It should be understood that the illustrations are for the purpose of describing a preferred embodiment of the inventions and are not intended to limit the inventions thereto.

A “big picture” presentation of a solar energy plant according to the present invention is depicted inFIG. 2. Following the flow of energy, the major components are the solar panels S, junction boxes J, wire harnesses10, recombiner boxes R, inverter (DC to AC), transformer, and switch yard. Each solar panel S is connected to a junction box J, which may be integrated or separate. Each junction box J is in communication with one branch12of wire harness10(seeFIG. 3), typically with 6-12 branches, and 12 branches per wire harness being preferred. Each wire harness has one trunk14, which is in communication with a recombiner box R.

Recombiner box R preferably accommodates 12-24 trunks14, corresponding with 12-24 individual wire harnesses10, as schematically represented inFIG. 2as “phantom” wire harnesses10. Recombiner box R is in communication with an inverter, preferably with 6 gauge wire. The inverter preferably accommodates 8-10 recombiner boxes R, as indicated by the “phantom” recombiner boxes R connected to the inverter.

Conventionally, combiner boxes contain fuses (C w/F), as shown inFIG. 1. In the present invention, however, fuses are upstream of the “combiner box” (recombiner box R), in wire harnesses10. Accordingly, recombiner box R of the present invention is preferably devoid of fuses.

Referring now toFIG. 3, wire harness10includes a plurality of branches12feeding into one trunk14. Preferably branches12are constructed of 10 or 12 gauge photovoltaic wire, with Southwire of Carrolton, Georgia being most preferred, and trunks14are constructed of 10 or 8 gauge photovoltaic wire, with Southwire of Carrolton, Georgia being most preferred. Branches12preferably terminate in connectors, with negative connectors40being most preferred. Trunk14preferably terminates in a connector, with positive connector45being most preferred. Branches12connect to trunk14with cross joints50, or tee joints55, with the former uniting four wires and the latter uniting three. Trunk14is divided by joints into multiple trunk segments59.FIG. 3depicts a cross joint in exploded view, including encasement51having four protrusions52, vertices53formed at bases of protrusions, and securing apertures54at the vertices. Securing apertures54have a perimeter partially defined by spanning member56connecting one of said protrusions52to another of said protrusions. Securing apertures are particularly well suited for receiving fasteners such as zip ties, for holding the assembly in the field. While the cross joint is described, it should be understood that corresponding structures exist on other joints, such as tee joints, as well. These joints are disclosed in U.S. patent application Ser. No. 12/502,395, which was filed Jul. 14, 2009, and issued into U.S. Pat. No. 8,604,342, on Dec. 10, 2013, which is incorporated herein in its entirety. Various combinations of joints and connectors are capable of yielding a variety of wire harness10configurations. These various configurations are within the scope of the present invention.

Branches12of wire harness10each include one in-line fuse assembly20, so wire harness10includes a plurality of in-line fuse assemblies20connected to branch wire58, which is preferably photovoltaic wire. These assemblies20are separated one-from-another by cross joints50or tee joints55. Wire harness10is capable of withstanding high voltage, low current power. As used herein, “high voltage, low current power” means a voltage between 500V and 1500V, and a current between2A and60A; with voltage and current between 600V and 1200V, and2A and30A, respectively, being more preferred; and between 600V and 1000 B, and2A and20A being most preferred.

FIGS. 4-5depict one embodiment of in-line fuse assembly20, the in-line fuse assembly with a diode. Specifically, referring toFIG. 4A, assembled in-line fuse assembly20is encased on three sides by housing22, and covered on a fourth side by lid23. When lid23is removed,FIG. 4B, the structure of the various components are visible within housing22. Preferably, lid23and housing22are constructed of polypropylene, by conventional methods such as injection molding. Preferably housing22is approximately 138.5 mm long, 22.0 mm tall including flange24, 17.0 mm tall not including flange24, 22 mm wide, and having walls 2.0 mm thick. Preferably lid23is 138.5 mm long, 3 mm tall, 41 mm wide. In constructing in-line fuse assembly20, it is desirable to construct the device within housing22, then position lid23to encase the assembly. Housing22and lid23are preferably held together by ultrasonic weld or screws. Other embodiments of in-line fuse assembly20, with and without lid23, are similarly depicted inFIGS. 6A,6B,8A and8B.

Turning now toFIG. 5, this embodiment of in-line fuse assembly20includes, from left to right, input25constructed of assembly wire60, which is held in position by wire clip33, which is integrated into the housing22. As with all embodiments, assembly wire60may be the same as branch wire58, except it is considered directly associated with in-line fuse assembly20. Preferably assembly wire60is 10 or 12 gauge, with Southwire of Carrolton, Ga. being most preferred. In this embodiment, a “stub” of branch wire58is attached to assembly20via wire grommet62, with assembly wire60in communication with crimp connector35, and blocking diode28. Diode28preferably has an ampacity of 2 to 30 amps, and is commercially available as P600 from Vishay of Shelton, Conn.

Downstream from diode28in the embodiment is midget fuse30, which is held in position by fuse clips34, which are integrated with housing22. Midget fuse30preferably has an ampacity of 2 to 30 amps, and is commercially available as an ATM fuse from Ferraz-Shawmut of Newburyport, Mass. Grommet62locates assembly wire60, which connects to midget fuse30by fuse clip34, and is output26of assembly20. Grommets62protect housing-22and lid-23encased assembly20from ambient.

The in-line fuse with diode embodiment, as depicted inFIGS. 4 and 5, as well as other embodiments discussed herein, provide multiple structural differences and functional advantages over conventional solar industry components. Specifically, by employing a wire harness versus conventional hard wiring, the labor costs and failure rates are significantly decreased. This is because a trained technician can plug in the appropriate parts, versus an electrician performing conventional hard wiring methods. Also, when fuse20needs to be replaced, it is possible to simply isolate and swap out a bad fuse for a good one on harness10, rather than dealing with the combiner box C w/f, which can be more difficult to diagnose, and more hazardous and complex. By positioning fuse20upstream of recombiner box R, one blown fuse merely shuts off power flowing from the single associated solar panel S, versus shutting down power flowing from all solar panels connected to the portion of the associated recombiner box. This drastically decreases the negative impact of “down time”, thereby improving the efficiency of the total solar field. Also, the master fuse box is eliminated, thereby simplifying and cutting costs. Moreover, by providing a blocking diode, energy can not reverse the flow and drain power from the system.

FIGS. 6-7depict another embodiment of in-line fuse assembly20, the in-line fuse assembly without a diode. This embodiment is similar to the embodiment ofFIGS. 4-5, except that it doesn't have crimp connector35or diode28. Assembly wire60is longer, and can include 1000V fuse31, which is commercially available as DCT series from Ferraz-Shawmut of Newburyport, Mass.

FIGS. 8-9set forth yet another embodiment of in-line fuse assemblies20, the in-line fuse assembly with connectors. By including negative connector40and positive connector45, it is possible to easily “swap out” in-line fuse assembly20in the field, in the event of a blown fuse or other failure. AlthoughFIGS. 8B and 9depict assembly20without diode28, it is possible to include diode28, depending on the requirements. The bottom left branch12ofFIG. 3illustrates the embodiment of an in-line fuse assembly20including connectors40,45used in wire harness10.

Referring back toFIG. 2, in use, one would electrically connect junction box J of solar panel S to recombiner box R by plugging, for example, negative connector40(shown inFIG. 3) at distal end of branch12of wire harness10into junction box J. Similarly, each branch12of wire harness10would be plugged into a different junction box J, with each junction box J associated with one solar panel S. Positive connector45of trunk14would connect to central recombiner box R. In this manner, a plurality of solar panels S, with an equal number of junction boxes J, would be connected by an equal number of branches12to trunk14. Trunk14would be electrically connected to recombiner box R. In this manner, the number of trunks14would equal the number of wire harnesses10. The solar panel S would be positioned to collect solar energy. Wire harnesses10would include at least one in-line fuse assembly20, with each in-line fuse assembly including a fuse, for example midget fuse30or 1000V fuse31, and optionally diode28. Negative connector40and/or positive connector45could also be employed to provide “plug and play” functionality. When the embodiment including connectors (FIGS. 8 and 9) is used, it might not be necessary to unplug wire harness10from junction box J when in-line fuse assembly20requires replacement. Rather, in-line fuse assembly20could be “swapped out” for a replacement in-line fuse assembly.

By way of working example, a solar energy field using in-line fuse assembly20could be set up as follows: 2304 solar panels are connected to 16 recombiner boxes, primarily using the in-line fuse assembly, which is generally depicted inFIG. 5, which is commercially available as the STG-SHP-2X12P.M3 wire harness assembly from Shoals Technologies Group of Portland, Tenn. Accordingly, each wire harness assembly includes eight branches12feeding into each trunk14. The solar panel/junction box assemblies are commercially available from Sharp Electronics Corporation of Huntington Beach, Calif. as NA-128H5, and the recombiner boxes are commercially available from Blue Oak PV Products of Davis, Calif. as HCB12. Branches12and trunk14are constructed of 10 and 10 gauge wire, respectively. The output of the recombiner flows directly to the DC-to-AC inverter. In this manner, each branch12carries a maximum of 1000V and 2 A, and each trunk14carries a maximum of 1000V and 16 A, the total maximum output per recombiner box is 1000 V and192A, and the total maximum output of the DC-to-AC inverter is 3 MW. In the event one solar panel P stops collecting energy, or fuse30or31is blown, the entire system output would only be decreased by2A, or 0.06%.

Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. By way of example, the fuse only version can be placed in a shorted housing. 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.