Roof Integrated Solar Panel System with Ridge Mounted Micro Inverters

A solar panel system includes a plurality of solar modules that produce DC electrical energy when exposed to sunlight. Each of the solar modules includes a frame, a photovoltaic panel mounted to the frame, and an electrical coupling for outputting the DC electrical energy from the photovoltaic panel. The solar modules are mounted to the deck of a roof having a ridge and a ridge vent extending at least partially along and covering the ridge of the roof. One or more micro-inverters is located beneath the ridge vent and each is electrically connected to a bank of two or more solar modules selected from the plurality of solar modules. The micro-inverters on the roof convert the DC electrical energy produced by the photovoltaic panels to AC electrical energy, and the AC electrical energy is aggregated from the micro-inverters and delivered to a remote electrical system.

DETAILED DESCRIPTION

Referring now in more detail to the drawing figures, wherein like reference numerals, where appropriate, indicate like parts throughout the several views,FIG. 1illustrates a section of a pitched roof commonly found in residential homes. The roof includes a roof deck16supported by rafters15(FIG. 2) and extending from a lower edge or eve upwardly to a ridge. In the illustrated embodiment, the ridge of the roof is formed with a ridge slot14for ventilation of an attic space below the roof. The roof deck16is illustrated as being plywood inFIG. 1, but may be other materials commonly used to deck roofs. Further, it will be understood by the skilled artisan that a membrane such as roofing felt or other material typically can be applied atop the roof deck and may overlie the roof deck even through it is not shown in the drawing figures.

A roof integrated solar panel system11is mounted on the roof inFIG. 1and comprises a plurality of solar modules12secured in courses atop the roof deck. A special ridge vent13can extend along the ridge of the roof covering the ridge slot14. Where the ridge vent is not used for ventilation of the attic space below the roof deck, there may be no ridge slot. The solar modules12in the illustrated embodiment are aligned with each other from course to course, but may be installed in staggered or installed in other patterns if desired.

Each solar module12generally includes a frame17and a photovoltaic panel18. The frame17may be formed of molded or extruded plastic or other polymer material, formed of aluminum, formed of a composite material, or otherwise made of a material resistant to years of harsh environments encountered atop a typical roof. Each module has a forward edge, a rear edge, and left and right ends. In addition, the frame17of each solar module12can be slightly wedge shaped in cross section being thinner along the rear edge than the forward edge. In one aspect, the maximum thickness of the frames17can be less than or about one inch, or even less than or about one-half inch, so as to form a low-profile covering that extends across the surface of the roof deck16and has an appearance similar to that of more traditional roofing systems.

The forward edge of each frame17can be formed with an undercut groove29(FIG. 2) sized and configured to receive and overlap the rear edge portion of a solar module in a next lower course, which is referred to as the headlap23. In this way, the modules of the system function to shed water during rain in a manner similar to traditional shingles. A starter strip24can be affixed along the forward edge portions of the lowermost course of modules and configured to nest within the undercut grooves29of these modules to support the modules and provide a weather barrier.

The frame17of each module carries a photovoltaic panel18, which may be protected by a glass covering, a polymer coating, or other transparent material resistive to the elements. When exposed to sunlight, the photovoltaic panels18generate DC electrical energy. An electrical coupling, such as a junction box21or similar coupling device, is provided to allow the photovoltaic panel to be electrically connected to the photovoltaic panels of other solar modules or to another destination. In one aspect, the junction box21can be located in the rear or headlap portion23of each solar module12and below the top surface of the frame17, and may thus be covered by the forward edge of an overlying solar module after installation.

A plurality of micro-inverters26are disposed beneath the ridge vent13where they are protected from the elements and also exposed to sufficient airflow to promote cooling of the micro-inverters during operation. Each micro-inverter converts DC electrical energy applied to its input to AC electrical energy at its output. In the illustrated embodiment, the DC electrical energy generated by two or more solar modules18can be applied through an electrical connector or wires27to the input of a corresponding micro-inverter26. Since each micro-inverter is generally dedicated to more than one solar module, the number of micro-inverters required can be reduced, resulting in a reduction of system cost. However, even in embodiments where only one solar module12is electrically coupled to a single micro-inverter26, advantages such as thinner modules, improved micro-inverter access and maintenance, and enhanced cooling, to name a few, are nevertheless realized.

In the illustrated embodiment, three solar modules12are electrically grouped into a “bank” of solar modules that is in turn connected to one micro-inverter at the ridge of the roof. It should be understood, however, that this is not a limitation of the invention and more or fewer solar modules, and even a single module, may be paired with each micro-inverter if desired. Although illustrated as being connected across several courses of solar modules, the electrically connected photovoltaic panels18/solar modules12in the grouping need not be physically connected or adjacent to each other, and may be spaced from each other across the plurality of solar modules, if so desired.

In addition, the number of solar modules12that are grouped into banks and electrically coupled to a single micro-inverter26can be optimized according to the power output of the of photovoltaic panels18and the power capacity of the micro-inverters26. Thus, the roof integrated solar panel system11of the present disclosure can also allow for “power matching” of the photovoltaic panels with the micro-inverters during the design stages of the solar panel system11for optimum efficiency and output.

Generally, the AC outputs of the micro-inverters26are then connected and aggregated together and delivered to a remote electrical system, such as the public electrical grid, a private electrical system in the building having appliances to be powered, or otherwise stored in batteries, used, or sold as desired.

FIG. 2is a side elevation of the system shown inFIG. 1illustrating three courses of solar modules12. The frame17of each module can slightly wedge shaped with a forward edge formed with an undercut groove29and a relatively thinner rear edge. The solar modules12can be installed on the roof deck16in courses, with the undercut grooves29of higher courses receiving and overlying the thinner rear edges or headlap regions of modules in lower courses, so that water is shed down the modules during rain. Thus, when the solar modules12are secured or mounted flush to the roof with the bottom surfaces of the frames17resting on the deck16of the roof (or upon the roofing felt layer, etc.), the installed courses of solar modules12can together form a water-shedding barrier that protects the roof deck16from moisture.

In addition to a frame17, each solar module12generally includes a photovoltaic panel18and an electrical coupling or junction box21from which output wires22extend. In the illustrated embodiment, three solar modules12, one from each of the three separate courses of solar modules, are electrically coupled together through their junction boxes21and wires22in a group or bank. The bank of three solar modules is in turn electrically coupled to a single micro-inverter26that is housed and protected beneath a ridge vent13extending along the ridge of the roof. Starter strip24is seen disposed in the undercut groove21of the lowermost course of modules to fill the groove, support the modules, and form a weather barrier. Additional groupings of modules12(whether vertical, horizontal, or some other footprint) can be similarly connected along the roof, as shown inFIG. 1, and can provide DC electrical energy to additional micro-inverters beneath the ridge vent. As stated above, the AC outputs of the several micro-inverters can be coupled together to deliver aggregated AC electrical energy to the remote electrical system for use or storage.

It is to be appreciated that other configurations and devices for establishing electrical connections between solar modules12and between the solar modules12and the micro-inverters26are also possible and considered to fall with the scope of the present disclosure.

FIG. 3illustrates one aspect of the end-to-end (i.e. side-to-side) connection between the frames17of two solar modules in the same course of modules. As shown, the overlap portion32of the left module can be formed along its bottom surface with a series of ridges and troughs34and the underlap portion28of the right module can be formed along its top surface with a series of complementing ridges and troughs36. When two modules are joined end-to-end to form a shiplap, their respective ridges and troughs can interleave to form grooves37between the overlapped portions. This, in turn, can prevent water from migrating laterally across the shiplap joint and thereby inhibits water leakage between modules in a course of modules. However, any collected water within the grooves37can migrate along the grooves and be shed to the next lower course of modules and eventually off of the roof deck.

FIG. 4illustrates one possible wiring schematic for electrically connecting banks of solar modules together and to their micro-inverter, and of connecting the micro-inverters of each bank together to deliver AC electrical energy to the grid. In the illustrated schematic, the photovoltaic panels18of three solar modules are shown electrically coupled together in a bank; however, more or fewer than three may comprise a bank such that any number of panels connected in a bank is within the scope of the invention. The three photovoltaic panels18in the illustrated embodiment can each produce a DC output when exposed to sunlight, and the DC outputs of each panel can be coupled in series with the DC outputs of the other photovoltaic panels in the bank. Thus connected, the voltages produced by the three panels are added together to produce a group DC voltage.

The group DC voltage of the connected bank of photovoltaic panels may be connected to the DC input of a micro-inverter26, which converts the DC voltage to AC electrical energy at the output of the micro-inverter. Other micro-inverters of other banks of solar modules can also produce AC electrical energy from the DC electrical energy produced by their corresponding bank of solar modules. The AC outputs of all of the micro-inverters of an installation can be electrically coupled together in parallel to aggregate the AC outputs of all micro-inverters. The aggregated AC electrical energy can then be delivered via a common electrical line41to a remote electrical system, such as the public electrical grid42, a private home electrical system, and the like, for use or storage.

FIG. 4illustrates one possible electrical schematic for interconnecting modules of the system. It will be understood, however, that many other ways of wiring and interconnecting the modules and micro-inverters are possible depending upon a desired output and result and all are considered to be within the scope of the invention. For instance, the DC outputs of the three modules may be electrically connected in parallel instead of in series as shown and/or the AC outputs of the micro-inverters may be electrically connected in series rather than in parallel. All useful electrical connection schemes should be considered to be within the scope of the invention.

The invention has been described herein in terms of preferred embodiments and methodologies considered by the inventor to represent the best mode of carrying out the invention. It will be understood by the skilled artisan; however, that a wide range of additions, deletions, and modifications, both subtle and gross, may be made to the illustrated and exemplary embodiments without departing from the spirit and scope of the invention set forth in the claims.