BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for collecting solar power and a building or other static structure incorporating the same.
2. Description of the Prior Art
Interest in solar power continues to accelerate in the face of global warming, concern over the long term availability of petroleum and the pressures of rising energy prices. Tapping even a portion of available solar power has the potential to reduce reliance on petroleum and to hopefully reduce pressures on the national energy grid by distributing power generating sources more locally. Even cutting external energy demands by three percent would have a significant impact on energy demand and therefore on energy prices. And recently some cities have joined the effort by loaning the money to buy solar equipment to residents to encourage residents to buy solar.
One drawback to solar power, however, is that it tends to have low thermal efficiencies and the amount of area that a home would need to break even for the year on energy requirements is very high. What is needed is a way to make the most of the solar energy available to power a home while minimizing the costs of the power system to make solar power more energy efficient, more attractive and financially more effective.
- SUMMARY OF THE INVENTION
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
According to a preferred embodiment of the present invention, two half cylinder troughs along a slanted roof of a building. The sun light entering the trough is reflected onto a secondary collector situated at a focus line of the primary collector. Light is directed onto a boiler tube contain a fluid to be used in an appropriate thermal cycle. Solar panels may be provided on surfaces along the secondary collector to power portions of the system. Braces can be provided to support the secondary collector over the primary collector. Reflectors may be provided to redirect light away from the braces onto the primary collector.
Accordingly, it is a principal object of a preferred embodiment of the invention to provide a highly efficient and cost effective solar system. It is another object of the invention to . . . .
It is a further object of the invention to . . . .
Still another object of the invention is to . . . .
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects of the present invention will be readily apparent upon review of the following detailed description of the invention and the accompanying drawings. These objects of the present invention are not exhaustive and are not to be construed as limiting the scope of the claimed invention. Further, it must be understood that no one embodiment of the present invention need include all of the aforementioned objects of the present invention. Rather, a given embodiment may include one or none of the aforementioned objects. Accordingly, these objects are not to be used to limit the scope of the claims of the present invention.
FIG. 1 is an environmental perspective of a static structure employing an embodiment of the present invention.
FIG. 2 is a perspective view of primary and secondary collectors of the present invention.
FIG. 3 is a diagrammatic view showing reflection of light in the primary collector.
FIG. 4 is a cross section of a secondary collector according to the invention.
FIG. 4 b is an end plan view of the primary and secondary collector according to a second embodiment of the invention.
FIG. 5 is a perspective view of the secondary collector and braces according to a further embodiment of the invention.
- DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
Similar reference characters denote corresponding features consistently throughout the attached drawings.
The present invention is to an improved method and apparatus for collecting and utilizing solar power, and a building incorporating the same. As shown in FIG. 1, a building 110 incorporating at least one solar trough 120 is shown. A portion of the building includes a downward slanting wall incorporating two side by side troughs 120. This wall preferably faces in the most efficient solar collecting direction to maximize the amount of sunlight hitting the face of the wall on an annual basis or using other algorithms to maximize, for example, the caloric impact of the sun (“solar incidental energy”) on the wall on a set periodic basis. Generally, the wall will face an Eastern direction so that as the sun rises, the sun will generally follow the longitudinal axis of the troughs 120. It should be noted that as the earth tilts through its orbit, the sun will track through 23 degrees north or 23 degrees south of the axis of the earth. The sun will thus substantially track parallel to the troughs as the earth tilts through its annual tilt cycle. As will be explained further hereunder, the vertical walls of the trough and optionally tilting of the collectors will act to maximize solar collection as the earth tilts through its cycle. The troughs could be extended to slope in a Westward direction as well to capture the afternoon sun, however, for simplicity, the invention will be described with regard to one trough, with the understanding that any number of troughs and trough orientations could be used. Preferably the troughs are built into the structure of the building, but one skilled in the art would recognize that the troughs could be added to the building later or independently affixed to the building. Preferably the troughs are incorporated into the structure of the building to increase the stability of the troughs, to prevent vulnerability to weather such as low pressure storm cells, and to increase the stability of the building to accept additional equipment such as air conditioning units that may be incorporated into the roof and solar system.
The trough itself (“primary collector”) 120 is preferably semicircular in profile, basically a hollow cylinder cut substantially in half. The trough faces upward to allow sunlight in to shine off each face and focus onto a central focus line (F-F, FIG. 2) that will be discussed further herein. The trough is preferably permanently tilted to maximize exposure to the sun. Depending on various requirements and applications, the degree of tilt may be varied, but preferably the degree of tilt is a function of the latitude of the building incorporating the solar receptor. Ideally, the degree of tilt is the same as the latitude, such that a building 20 degrees north latitude will have an angle as if the cylinder were sectioned 20 degrees relative to the earth's surface. This angular tilt (as opposed to the axial tilt of the centerline of the cylinders along the building wall or roof) causes the opening “face” (the plane along which a hypothetical cylinder would be cut to form the semicircular cross section) to point towards the mean path of the sun across the trough. In this way, the trough will have the greatest average sun light on the trough throughout the year. To further aid in collecting the maximum amount of sunlight, the semicircular cross section of the trough may not include the full 180 degree cross section. While in theory, rays at the extreme edges of the semicircle will still reflect and focus on the central foci, it has been found that removing a portion of the edge to reduce the shading effect of the outer walls provides greater overall solar energy capture than providing the full semicircular walls. Therefore, it is preferred to trim the trough walls to about 178 degrees, to maximize solar energy collection.
Optionally, as shown in FIG. 1, the trough may extend on more than one slanted wall to take advantage of morning and afternoon soon. The trough is divided perpendicular to the axis into two sections, with one section mounted on each opposing, slanted building wall in an inverted V shape. One wall is shown as the front side of the building 110, and the other wall is the back side of the A shaped building. In this way, the walls are preferably formed by cutting the trough in half perpendicular to its axial centerline to provide two like semicircular troughs. The first trough is mounted 20-40 degrees (i.e., axial center line to earth surface angle) towards the east and the second is mounted 20-40 degrees towards the west in an inverted V pattern. In this way one trough efficiently collects morning sun and the other trough efficiently collects afternoon sun. By distributing the collection of sunlight more regularly throughout the day, there are fewer (or smaller) peaks in the energy collected, allowing smaller boilers and other equipment downstream to be used.
One advantage of the trough configuration compared to flat solar panels is that the troughs are somewhat self cleaning. Water from rain storms or from induced spray run through the troughs under force of gravity to clean the troughs of any debris. The troughs may optionally have a water source associated at an upper end or along the troughs to allow the troughs to be cleaned periodically.
As shown in FIG. 2, running parallel to the axis of the primary collector (“trough”) 120 is a secondary collector 140. The secondary collector is located within the trough and surrounds the foci of the reflections within the trough. Unlike a normal solar panel, the trough is not made of panels that absorb the sun, but are instead made of panels that reflect the sun onto a second collector and from the secondary collector onto a boiler tube. Because the trough is nearly a complete half cylidnder (i.e., semicircular in cross section) and light from the sun enters the primary collector in substantially parallel rays, the sun light that is received within the primary collector will focus the light on or more accurately through a single point F (FIG. 3). One skilled in the art will recognize that since the trough is three dimensional and not just a two dimensional semicircle, that point F is actually a line F-F that parallels the axis of the trough, and that the focus line changes according to the direction from which light enters, but all light parallel to line E (including lines A, B and D) will reflect through the same focal line F-F.
As mentioned above, the primary collector 140 acts to focus all of the light going through point F (“line F-F”) through the opening of a secondary collector, which then focuses the light onto boiler tube 150. The boiler tube contains water or preferably a more suitable refrigerant which is designed or chosen for the particular thermal cycle which the fluid undergoes, but for purposes of clarity and simplicity, the fluid of the system will be referred to in this application as water.
FIG. 4 shows a cross sectional view of the secondary collector. Each wall of the secondary collector is preferably described by an ellipse to maximize reflection through the secondary collector directly onto the boiler tube 150. Each wall's elliptical vertical centerline is separated by a distance X. Overlapping portions described by the two ellipses is removed to form a heart shaped secondary collector. A bottom portion described by the ellipses is also removed to form a mouth 142 to allow the sun light to enter the secondary collector. The secondary collector preferably overlaps the focus point of the primary collector. More preferably, the mouth 142 of the secondary collector is aligned such that the focus point F is located in the middle of the lips (“lower most edge”) 144 of the mouth of the secondary collector. As shown by the lines B-E, the angular arrangement of the interior reflecting surface 146 of the secondary collector 140 act to reflect all received light onto the boiler tube 150. Additionally, the interior surfaces of the secondary collector may be enhanced to increase the reflectivity of the surfaces, especially by polishing or silvering. The boiler tube may have one central chamber as shown in FIG. 5, or may be divided into multiple chambers to heat various fluids. FIG. 4 shows a preferred embodiment having three separate chambers for heating three distinct fluids. The fluids in the various chambers may be the same type of fluid, but are capable of being run in separate, divided circuits, that is without mixing.
In a most preferred embodiment, solar cells are the side or sides of wing 148 near the mouth 142 of the secondary collector to catch stray solar rays. Light may reflect off the primary collector at a less than ideal angle due to surface imperfections, blockage caused by debris or for other reasons. Slight wings may be added to the lower end of the secondary collector near the mouth. Preferably the width of the wings does not substantially change the outer profile (i.e., does not cast additional shadow) of the secondary collector. The mouth 142 of the secondary collector is designed to be substantially larger than the focal point F to catch stray light. Light that is reflected just beyond the mouth that would normally be reflected out of the primary reflector back to the sky can be captured by these wings 148. Solar panels on the bottom and optionally on the top of the wing, catch sun light directed onto the wing. This additional energy may be utilized as needed, but is preferably used to power the functions of the solar collector itself, such as to rotate and/or align the secondary collector as will be discussed further below.
The top of secondary collector will generally point towards the sun. This will cause a shadow on the primary collector at a point below the mouth. The solar energy that would normally be wasted can be captured in part by providing solar panels 152 at the top of the secondary collector. Preferably, the total width (x′) of the top solar panels 152 is the same or nearly the same as the width (x″) of the body of the secondary collector to maximize the width of the solar panel without increasing the profile (“shadow”) of the secondary collector. Likewise, the wings 148 at the mouth of the collector are configured to have the same width as the secondary collector for the same reasons. It should be noted that the energy collected by the solar panel 152 will be directly related to the energy collected at the boiler tube 150, since the solar panels receive a fraction of the light that is also normally directed onto the boiler tube. This may be used in part to measure the light collected on or energy imparted to the boiler tube or for other purposes.
The secondary collector 140 is held in place over the primary collector 120 by a number of braces 160. While the primary and secondary collectors are preferably continuous along the length of the trough and have a substantially constant cross-section along the length, the braces 160 are only spaced intermittently along the trough. This is desirable to limit the shading effect of the braces on the primary collector. Any shade caused by the braces, which overly the primary collector, would reduce the amount of solar energy collected by the primary collector and thus needs to be minimized. The total number and size of the braces would depend on the weight and forces on the secondary collector, including forces from wind, rain, and snow.
These lateral braces 160 support the boiler tube and secondary collector preferably at both ends and in a series of spaced apart braces along the secondary collector. These braces preferably are insulated with a low conductivity material such as ceramics, especially where the braces connect to the boiler tube to minimize any heat losses from the boiler tube. As shown in FIG. 5, the brace may include a tube that connects to the boiler tube 160 by an insulated spacer block 161 In order to lessen the shading effect of the braces, each brace may have a reflector 162 mounted thereto to deflect the sun onto the primary collector. The brace reflector preferably includes an inverted V shaped reflector sloping away from the brace on either side of the reflector to maximize the amount of light deflected away from the brace. In this way the individual sloped plates of the bracket reflectors reflect away from the boiler tube as well and on to the primary collector. Insulators around the boiler tube can be discontinued where the braces are to minimize the shading on the primary reflector. The braces are preferably attached to the secondary reflector and boiler tube to allow the secondary reflector rotate for the reasons discussed below. The boiler tube and the secondary reflector may rotate together, but preferably the boiler tube is fixedly connected to the braces and the free floating secondary collector is connected to rotate about the cylindrical boiler tube. A cutout 163 may be provided on the secondary collector to allow the collector to rotate about the brace without interfering with the braces.
The secondary collector is preferably assembled as one continuous piece as shown in FIG. 5, but may also be divided into continuous sections between the braces. The sections of the secondary collector may be joined together to rotate as one unit or may be separate pieces that are rotated in coordination with each other, depending on the amount of rotation desired and the location of the location and number of braces as the braces will tend to limit the amount of rotation that joined sections of secondary collectors can rotate about the boiler tube without interfering with the braces.
Any method can be used to rotate the secondary collector about the boiler tube, including friction wheels between the secondary collector and the boiler tube, a stationary member on the boiler tube with a movable arm, etc. Any method that allows the secondary collector sections to move, preferably simultaneously or in a coordinated manner.
The secondary collector is preferably moved periodically to constantly point towards the sun throughout the day and or seasons, or more correctly, the mouth of the secondary collector is pointed directly away from the sun. In theory the trough is aligned parallel to the track of the sun and the collector will only have to be turned slightly each morning. However, this ability to rotate will also provide a correction mechanism for a misaligned trough or one that has shifted. Of course, one could also build an alignment adjustment mechanism into the trough connection to the static structure (“building”) to make slight alignment adjustments to the positioning of the primary collector trough during or after installation.
One preferred mechanism for tracking the sun involves placing a small hole 154 through the top solar collector 152 or at a break therein. By providing light sensors, photovoltaic sensor strips, charged capacitor devices or similar devices that can determine when the sun points at a position other than directly on line, the location of the light on the detectors around the target can be used to determine the current position of the secondary collector relative to the sun, such as by comparing measurements on various sensors. This information can be used to determine how to re-aim the secondary collector to maximize collection of the solar energy while minimizing the shadowing of the collector on the primary collector. Additionally or as an alternative, a daily estimation or annual historical data table can be used to pre-move the secondary collector a set amount for the day or for that particular day. Preferably energy collected and/or stored from the secondary solar cells such as those on the wings 148 and/or solar collector 152 of the secondary collector are used to rotate the secondary collector, but one skilled in the art would appreciate that other sources of power could be used. The energy derived from the solar panels 148, 152 can also be used to run pumps, such as for the fluid(s) in the boiler tube, or for other purposes.
The fluid in the boiler tube is thus heated to a maximum amount and can be circulated through an appropriate system to utilize the fluid to generate electricity, run air conditioning or heating systems, to heat water or for other purposes. By efficiently directing solar energy onto the boiler tube, solar energy can be used more efficiently than present systems. The exact usage of the fluid heated by the present system is elective and should not be used to limit the claims of the present application.
While this invention has been described as having a preferred design, it is understood that it is capable of further modifications, uses and/or adaptations of the invention following in general the principle of the invention and including such departures from the present disclosure as come within the known or customary practice in the art to which the invention pertains and as maybe applied to the central features hereinbefore set forth, and fall within the scope of the invention and the limits of the appended claims. It is therefore to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims.