Patent Application
20110168162
PPA filed Sep. 18, 2009 Ser. No. 61/277,014
NONE
NONE
This application relates to sun trackers, which are used to increase the output of solar cells. The idea of producing electricity from the sun has been around for over one hundred years. While the efficiencies of solar cells continue to rise, they remain costly to produce. Recently, an attempt has been made to lower the cost of solar power by concentrating the sun's rays onto a solar collector. This concentrated sunlight can then be either converted directly into electricity by a solar cell, or be used to boil water and drive a turbine. This, however, presents a new challenge. For solar concentrators to work, some means of accurately tracking the sun must be employed. Unfortunately, all known methods compromise cost, accuracy, and complexity.
For example, U.S. Pat. No. 4,027,651 to Ronald W. Robbins, Jr. (1977) uses an opaque divider between two sets of liquid-filled coils. Whichever set received more radiation gets hotter, the liquid boils, and the solar cells move in that direction. Although simple, it could not deliver a high degree of accuracy because of the large temperature difference needed. Also, it could not be used in extreme climates. Other methods provide more accuracy, but tend to me complex and costly. U.S. Pat. No. 5,600,124 to Alexander Berger (1997) was able to bypass air temperature problems, but needed a complex mechanical drive to operate. For large scale energy production, fields of mirrors have been used to concentrate sunlight onto a solar tower. The concentrated light boiled water and drove a turbine. However, every individual mirror needed its own precise path, which was controlled by a complex and costly computer program.
The cost of fossil fuels continues to rise, and easy sources are becoming harder to find. We are already running out of options other than to extract them from environmentally and politically sensitive areas. Unless a practical alternative is found and utilized soon, widespread habitat destruction and political confrontations(wars) are likely in these areas. Every day, enough sunlight strikes the earth's surface to supply mankind's energy needs for hundreds of years. Clearly, an effective means of harnessing the sun's extreme power is needed.
A simple, portable, low-cost, and user-friendly device for accurately tracking the sun. It uses no exotic materials, and can be used anywhere. It can be made to a wide range of sizes, suiting virtually any demand.
The daily movement of the sun is sensed by individual cells which are arranged in a semi-circular pattern. Each cell contains a simple device that senses the temperature difference between sun and shade. When a cell is activated by sunlight, it closes an electrical circuit to rotate a solar concentrator from east to west. The seasonal movement of the sun from high to low in the sky is sensed by a separate device on the same unit. This sensor operate on the same principle as the beforementioned cells, except that it rotates up and down with the seasonal sun and keeps the solar concentrator at the same angle
The sun tracker uses a simple electro-mechanical system of rotating wheels and electrical contacts, eliminating the need for an operator or computer system while providing a high degree of accuracy. This sun tracker can also be made on an assembly line using common materials and techniques, making it available to the general population.
These two bi-metallic strips are encased inside of a housing(14) that completely encases them, except for a slit(15) in the top(
At the center of each side of SAS housing perpendicular to SAS strips there is an axle stud(207) which sticks out from unit. Underneath SAS is a toothed gear(208) which covers no less that 47 degrees of arc, and centers on a line drawn between said axle studs. Said gear is perpendicular to direction of said SAS strips. There is a motor(209) underneath said gear which rotates very slowly.
On one side of the SAS that has an axle stud, there is a series of electrical contacts(210) which are arranged in a semicircle. Said semicircle takes up 47 degrees of arc and all contacts are equidistant from said axle stud.
The positive terminal on battery C is wired to one bare strip on SAS and one terminal on seasonal motor. The negative terminal on battery C is wired to one terminal on SAS motor an done plate on adjacent SRC. The positive terminal on battery D is wired to SAS bare strip not beforementioned. The negative terminal on battery D is wired to positive terminal on battery C and SAS motor terminal not beforementioned. Each SAS contact is wired to a corresponding contact on seasonal gear seasonal motor contact is wired to seasonal motor terminal not beforementioned.
Tracking unit is placed with the SAS pointing directly upward, and SAS studs point due east/west. Entire unit is then rotated, with SAS moving towards the earth's equator, the number of degrees as the latitude unit is being used at. For example, let's assume the sun tracker is being used in the District of Columbia, latitude 38.85° N. Looking east, tracking unit will be rotated clockwise from vertical just short of 39 degrees. Unit is then locked in place by tightening the hex nuts on supporting rod. Then SRC's are placed onto the unit so that they cover at least as much as fifteen degrees for every hour of sunlight on the summer solstice. Thus, in D.C., enough SRC's will be placed on the unit to cover 255 degrees for fifteen hours of daylight. SAS is then adjusted so that light beam falls between SAS black strips.
Concentrator assembly is then mounted so that the plane of the wheel is at the same angle to the ground as the tracking unit. A line drawn from the center of said wheel through the center of a wheel contact would point to the same point in space as a line drawn from the center of tracking unit through the center of said wheel contact's corresponding SRC. Concentrator assembly is mounted far enough off of the ground or other supporting structure so that concentrator assembly can rotate 360 degrees and solar concentrator can rotate 23.5 degrees up and down without hitting any solid object. Electrical wiring is then completed to the batteries. As this is done, electricity will run through SAS circuit and move concentrator so that it is at the same angle as the sun. If the sun is not shining already, when it does so next, it will shine on the black strip in one SRC. The strip will absorb radiation, heat up, and bend due to its bi-metallic nature. When it has bent enough to tough the contact on the bare strip beside it, an electrical circuit is completed through the SRC, its corresponding base contact, wheel plate, and base motor. Concentrator assembly then rotates until the gap between the two plates is centered above the energized base contact. Circuit is broken, and the solar concentrator is now pointed directly at the sun.
As the sun moves from east to west, its light will move off of the black strip it was before shining on. The sun will now be in direct alignment with the next SRC black strip going west, and an electrical circuit is completed through the next base contact. Concentrator assembly rotates until gap between plates is aligned with the newly energized base contact and stops. If the sun has not been shining for at least twelve hours, as is the case with a winter night or a considerably cloudy summer day, the energized base contact will then be touching the other wheel plate. The circuit through this plate is wired so that electricity flows the opposite way through base motor. Concentrator assembly will then move from west to east because that would be the shorter path to realignment with the sun. as the weeks go by, the sun will change its angle with the horizon. As the noon sun gets lower or higher in the sky, the beam shining through the lens in the SAS will move onto one of the black strips. When enough light is shining on this black strip, it will heat up and tough the contact on the bare strip beside it. An electrical current is completed through the SAS motor, and SAS slowly rotates in the direction of the sun. As SAS rotates, sunlight moves off of the strip it was shining on. Strip cools down, breaks the circuit, and SAS stops. As SAS rotates, its contacts move along the adjacent SRC strips. When SAS has moved enough so that the SAS contact which corresponds to the seasonal gear contact touching the seasonal motor contact now touches an SRC plate, an electrical circuit is completed through the seasonal motor. Concentrator will move vertically until the newly energized seasonal gear contact moves off of the seasonal motor contact. Circuit is broken, and solar concentrator is now seasonally adjusted.
When the sun reaches a solstice and moves in the opposite seasonal direction, the SAS black strip not beforementioned will receive the radiation, heat up, and close a circuit in which electricity flows in the opposite direction through the SAS motor. SAS moves in opposite direction, as does the concentrator.
As can be seen, at least one embodiment of this sun tracker provides accurate tracking of the sun on a daily as well as a seasonal basis without the need for an operator, complex mechanical, or costly computer control. No device currently in existence can accomplish this. It can be used in any climate, anywhere on Earth. With simple modifications to the lengths of the tops of the SRC's, this sun tracker can even be used on extra-terrestrial surfaces. Also, one tracking unit can be wired in parallel to a virtually unlimited number of concentrators, further simplifying use.
Although my description and drawings contain many things, many are irrelevant to the specific technology I have invented. They only show one way of using it, and therefore should not be used to limit the scope. My invention should be defined by the following claims, and not by the preceding description. For example, contained fluids may be used instead of bi-metallic strips. The tracking unit may be immobilized by clips instead of nuts. Concentrating lenses may be used in the SRC gaps to further increase accuracy.
| Number | Date | Country | |
|---|---|---|---|
| 61277014 | Sep 2009 | US |
