Solar-powered soffit fan

Abstract

The solar powered soffit fan includes an electric fan mounted over a soffit vent. A roof-mounted photovoltaic solar panel aimed at the sun delivers power to the soffit fan. During daylight hours, the photovoltaic solar panel provides sufficient electrical power to activate the soffit fan, which provides forced attic ventilation through the soffit vent. At night, the fan automatically powers down when sunlight no longer impinges the solar panel. A thermostat and/or humistat can be included for additional control of the unit. The fan can accept power from an optional rechargeable battery. Multiple soffit fans can be configured to service larger buildings.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/282,604, filed Mar. 5, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to building attic ventilation, and more specifically to an easily installed solar-powered soffit fan.

2. Description of the Related Art

Buildings usually incorporate ventilation systems in their attics to limit the adverse effects of heat and humidity build-ups in said spaces. The air in an attic is heated by solar energy through the roof and related supporting exterior structure. During night, roofs radiate heat and cool to ambient air temperature. This, in turn, cools and condenses air below the roof in attics. The air becomes more humid, and surface dampness can result. When the sun rises, it starts to heat the roof and facing structure, which in turn heats the air space in the attic.

The transfer of heat from the attic air to the adjacent living areas adjacent to the attic is directly proportional to the temperature difference between the attic air and the air in the adjacent living areas. As the air temperature in the attic rises due to solar energy, the air temperature in enclosed living spaces usually rises, requiring additional room ventilation, and/or air conditioning to maintain acceptable living and storage temperatures.

In an attempt to overcome excess humidity in attic crawl spaces, builders have installed passive soffit-mounted vents, which allow the air in an attic to circulate out through the vents. Passive ventilation works in ideal ambient conditions, however may not be effective on windless days when the ambient air is hot, humid, and stagnant.

A soffit-mounted fan would solve the problem. However, traditional soffit fans require running an electrical cable from the building circuit box to the unit. A unit having an independent power source would be highly desirable.

Thus, a solar powered soffit fan solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The solar-powered soffit fan includes an electric fan that is mounted over a soffit vent. A roof-mounted photovoltaic solar panel aimed at the sun delivers power to the soffit fan. During daylight hours the photovoltaic solar panel provides sufficient electrical power to activate the soffit fan, which provides forced attic ventilation through the soffit vent. At night, the fan automatically powers down when sunlight no longer impinges the solar panel. Mounting the fan over the soffit vent obviates the necessity of attic entry, roof access, and the like. Use of the roof-mounted solar panel obviates the necessity of running electrical power conductors from an external source, such as an electrical power panel. A thermostat and/or humistat can be included for additional control of the unit. The fan can accept power from an optional rechargeable battery. Multiple soffit fans can be configured to service larger buildings.

These and other features of the present invention will become readily apparent upon further review of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an environmental, perspective view of a solar-powered soffit fan according to the present invention, shown with portions of the building omitted or broken away to show details thereof.

FIG. 2 is a partially exploded environmental, perspective view of the solar-powered soffit fan according to the present invention.

FIG. 3 is a perspective view of the fan of FIGS. 1 and 2.

FIG. 4 is a partial environmental perspective view showing an exemplary solar panel installation for a solar-powered soffit fan according to the present invention.

FIG. 5 is a partial environmental perspective view of a solar-powered soffit fan according to the present invention, showing an exemplary method of connecting the fan to the solar panel.

FIG. 6 is a block diagram showing exemplary components of a solar-powered soffit fan according to the present invention.

FIG. 7 is a perspective view of an alternative embodiment of a solar-powered soffit fan according to the present invention, showing a housing for three soffit fans.

FIG. 8 is a partially exploded, environmental perspective view of the solar-powered soffit fan of FIG. 7.

Similar reference characters denote corresponding features consistently throughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1, 2, 4 and 6, the solar-powered soffit fan, designated generally as 10 in the drawings, includes an electric fan 20 which can be surface, flush or insert mounted over a soffit vent 11 that has free air access to the attic 12 of a house H or other type of building. At least one photovoltaic solar panel 25 mounted on the building structure, e.g., roof-mounted, and aimed at the sun delivers power via a power cable 40 to the soffit fan 20. During daylight hours the photovoltaic solar panel 25 provides sufficient electrical power to activate the soffit fan 20, which provides forced attic ventilation through the soffit vent 11. At night the fan 20 automatically powers down when sunlight no longer impinges the solar panel 25. As shown in FIG. 6, a thermostat 30 and/or humistat 35 can be included for additional control of the fan 20.

An optional charge-control device 78 and battery B can be added for operations into nighttime, or when there is insufficient sunlight to energize the solar panel 25. The charge control 78 automatically uses electricity from the solar panel 25 to charge the battery B. It also provides over-current and over-voltage protection to the battery B, fan 20, and wiring. The battery B and the control 78 are mounted on the outside of the building under the roof overhang, either to the overhang itself or a wall of the building, with screws, a bracket, and a weathertight enclosure adjacent to the fan 20 and solar panel 25 on the outside of the soffit.

Mounting the fan 20 over the soffit vent 11 obviates the necessity of attic entry, roof access, and the like. Use of the roof-mounted solar panel 25 obviates the necessity of running electrical power conductors from an external source, such as an electrical power panel. Multiple soffit fans 20 can be configured to service larger buildings.

As shown in FIG. 3, the fan 20 is preferably a low voltage, direct current, coaxial fan having fan blades 39 and a motor M mounted inside of a substantially arcuate shroud or housing 21a, which extends into a substantially rectangular mounting base 21b. The fan assembly 20 is chosen for suitability for exterior applications, and for compatibility with the solar panel 25. A protective screen 33 covers the intake/exhaust port of the housing portion 21a.

The fan 20 preferably is an assembly that has a brushless motor M, low inertia, low weight, and high-quality sealed bearings, and is preferably constructed of non-corrosive materials. The fan 20 should run at 12-volts DC or less. The housing base 21b is aligned with and covers the soffit vent opening 11 in a manner that allows the fan to efficiently take in and discharge air, and is secured in place with appropriate fasteners. The rectangular base 21b is flanged to allow screw mounting on the soffit peripheral to the soffit vent 11. The cross-sectional area of the soffit opening should be approximately the same as that of the fan 20. The fan housing or cowl should completely cover the soffit opening 11 and should be sealed at the edges around the base portion 21b to prevent forced air leakage around the fan 20.

Intake or exhaust is accomplished by e.g., swapping connectivity of the wire connectors to reverse voltage polarity in order to change the direction of rotation of the motor M of the fan 20, or when motor direction is unchangeable, by e.g., reversing the pitch of the fan blades with respect to the soffit opening. Preferably, the fan 20 is located on the opposite side of the structure from other attic ventilation openings, such as soffit vents, ridge vents, or gable vents, in order to maximize the cross flow of forced air through the attic.

Individual air movement, volume capacity, and the number of fans 20 used are based on the volume of attic to be ventilated in accordance with common industry standards.

The solar panel 25 is removably mounted with non-corrosive fasteners via a pivotal attachment of its elongate, side frame members 9c to a U-shaped bracket 9a, which is attached to the roof edge board 13 (fascia) as close to the fan 20 as possible. Alternatively the solar panel 25 is mounted on the fan housing to minimize electrical losses from the run of power cable 40.

The pivotal support brackets 9b extend down from the solar panel 25 and can be adjusted to rest on the top of the gutter G. In the event of a pending tropical cyclone, the panel 25 can be removed by loosening two screws (preferably thumbscrews) on the U-shaped bracket 9a and disconnecting the cable 40. The solar panel 25 is oriented to maximize daylight striking the panel 25 throughout the day and throughout the year. Typically, this is with a solar panel axis in an east-west orientation without sources of shade during the day. The panel 25 should be tilted toward the sun about the horizontal axis, the degree of tilt depending on the latitude of the location. The tilt can be adjusted seasonally for the declination of the sun's seasonal path for more direct sunlight, or it can be held in a fixed position year round. The solar panel 25 should be mounted to overhang free of structures, thereby preventing overheating and loss of effectiveness.

The photovoltaic solar panel 25 has voltage, current, and power (watts) ratings that are specifically matched to the motor M of the fan 20. Low voltage, low resistance, insulated copper wire cable 40 is connected with non-corrosive fasteners, hangars, and plug disconnects.

As most clearly shown in FIG. 5, the solar panel positive and negative wires are connected to their corresponding polarity fan motor conductors, preferably with plug disconnects (plugs 50a and 50c mating with receptacles 50b and 50d).

Sunlight strikes the solar panel 25. The solar panel 10 generates electricity and sends it by connecting wires to the fan 20. The blades 39 of the fan 20 spin, thereby drawing cool, ambient outside air from under the soffit and sending it through the soffit vent 11. The cool air enters the attic of the house H and mixes with the heated or moisture-laden air of the attic, cooling and drying it. It also displaces mixed air out of an opposing soffit, ridge, or gable vent, thereby forcing the mixed air and the entrained heat and moisture to the exterior of the building H. Two units 10 may be connected in a push-pull airflow arrangement through the attic.

The thermostat 30 and/or humistat 35 can control the start, run, and stop cycles of the fan 20 according to preset desired temperature and/or humidity. This can be advantageous in climates and circumstances when the outside ambient air may be warmer, cooler, or more humid that the attic air, and when a delay in starting forced attic ventilation may be incrementally advantageous.

Thermostat 30 is a normally open, fixed set point temperature thermostat suitable for solar attic fan applications and can be connected in series with the positive conductor of the electrical circuit between each solar panel 25 and each fan motor M. A normally open, fixed set point humistat 35 can be connected in series in the positive wire of the electrical circuit between each solar panel 25 and each fan motor M. Alternatively, the thermostat 30 is connected electrically in parallel with the humistat 35, and the combination is connected in series in the positive wire of the electrical circuit between each solar panel 25 and each fan motor M.

The humistat 35 or parallel combination is mounted with screws as far as practicable inside the soffit opening 11 for accurate sensing of attic temperature and/or humidity.

The solar-powered soffit fan 10 may be configured in three different modes. In one mode, the fan 20 is configured to draw cool, ambient outside air from below the soffit into the attic. In a second mode, the solar-powered soffit fan is configured to exhaust hot air from the attic out to the exterior of the building through the soffit vent. In a third mode, a first solar-powered soffit fan is configured to blow cool outside air into the attic, while a second solar-powered soffit fan is simultaneously configured to exhaust hot air from the attic to the exterior of the building, creating a push-pull airflow effect.

As shown in FIG. 7, an alternative embodiment fan assembly 720 includes a plurality of fans in a single unit. A wiring harness 702 electrically connects together individual fans of fan assembly 720. The female connectors 50b and 50d accept voltage to actuate the fans. The fan assembly 720 includes a 16″×8″ standard soffit vent louver-integral screen combination 711.

As shown in FIG. 8, fan assembly 720 fits into soffit opening and connects to semi-rigid flexible ductwork 810 which directs airflow between the soffit fan assembly 720 and the building's attic portion.

It is to be understood that the present invention is not limited to the embodiment described above, but encompasses any and all embodiments within the scope of the following claims.

Claims

1. A solar-powered soffit fan, comprising:

at least one exterior soffit fan and housing therefor adapted for mounting over a clear airflow opening in a soffit of a building structure;

a solar photovoltaic panel adapted for mounting on the building structure proximate the fan;

an electrical power cable electrically connecting the solar photovoltaic panel to the soffit fan; and

a protective screen attached to the soffit fan housing over an intake-exhaust portion of the soffit fan housing.

2. The solar-powered soffit fan according to claim 1, wherein said at least one soffit fan comprises a plurality of fans electrically connected to each other, the fans being disposed in a single housing.

3. The solar-powered soffit fan according to claim 1, further comprising a semi-rigid flexible duct connected to said soffit fan housing, the duct directing airflow between the soffit fan assembly and the building structure's attic portion.

4. The solar-powered soffit fan according to claim 1, further comprising a thermostat electrically connected to said solar-powered soffit fan, the thermostat controlling start, run, and stop cycles of said soffit fan according to a preset desired temperature.

5. The solar-powered soffit fan according to claim 1, further comprising a humistat electrically connected to said solar-powered soffit fan, the humistat controlling start, run, and stop cycles of said soffit fan according to a preset desired humidity.

6. The solar-powered soffit fan according to claim 1, wherein said at least one soffit fan is configured for drawing cool, ambient outside air from below the soffit into the building structure's attic.

7. The solar-powered soffit fan according to claim 1, wherein said at least one soffit fan is configured exhausting hot air from the building structure's attic out to the exterior of the building through the soffit opening.

8. The solar-powered soffit fan according to claim 1, wherein said at least one soffit fan comprises a first soffit fan configured to blow cool outside air into the building structure's attic and a second soffit fan configured to simultaneously exhaust hot air from the buildings structure's attic to the exterior of the building, thereby creating a push-pull airflow effect.

9. The solar-powered soffit fan according to claim 1, wherein the solar photovoltaic panel mounting has tilt adjustable members allowing said solar photovoltaic panel to be tilted toward the sun.

8. The solar-powered soffit fan according to claim 1, further comprising:

a battery operably connected to said solar-powered soffit fan;

a charge control device electrically connected to said solar panel and to the battery, said charge control device selectively using electricity from said solar panel to charge the battery, the battery being configured to power said soffit fan when there is insufficient sunlight to energize said solar panel.