WO2008117297A2

WO2008117297A2 - Solar energy collecting system

Info

Publication number: WO2008117297A2
Application number: PCT/IL2008/000491
Authority: WO
Inventors: Oren Aharon
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-03-25
Filing date: 2008-04-10
Publication date: 2008-10-02
Anticipated expiration: 2009-09-25
Also published as: WO2008117297A3; IL182390A0

Abstract

A solar energy collecting and concentrating system which includes a planar array of optical concentrating lens, for concentrating the sun energy and imaging the solar energy onto a two dimensional image formation area. A solar cell is used for converting said energy collected onto said formation area into other form of useful energy. A sun position detector is capable of tracking the sun's momentary location. A tracking subsystem consisting of a mechanical mechanism and an electronic control is capable of placing the solar cell in the image formation area to coincide with the suns momentary image location.

Description

SOLAR ENERGY COLLECTING SYSTEM

FIELD OF THE INVENTION

The present invention relates to solar energy systems. More specifically the present invention relates to a system and method for increasing the efficiency of collecting solar energy.

BACKGROUND OF THE INVENTION

The sun generates a vast amount of energy, efficiently collecting this energy and converting it to usable power is a goal of many.. Currently, solar energy uses can be grouped to three primary categories: heating, electricity production, and chemical processing. There are many technologies for harnessing solar energy. Applications of solar energy span through the residential, commercial, industrial, agricultural and transportation sectors. Photovoltaic systems are solar energy supply systems which either supply power directly to electrical equipments or feed energy into the public electricity grid. As price of fuel has increased dramatically and the adverse effect of fossil energy is now clear, the market for photovoltaic systems has increased dramatically. In addition, other characteristics such as reliability, simplicity, low maintenance, freedom from pollution increased their popularity even further. A

Concentrator is a system that concentrates the sun's power into a smaller area. Concentrators equipped with solar cells are an evolving technology for increasing efficiency of solar energy collection but are not yet mature due the high cost involved in building efficient solar energy collectors and trackers.

It is therefore the purpose of this invention to offer a solution of prior art drawbacks, such as: price, limited collection power, obstruction of natural light and other.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1A: Is an isometric schematic top view of an array of solar concentrating elements arranged in a tracking system in accordance with the preferred embodiment of the present invention;

Fig. 1 B: Is an schematic isometric bottom view of an array of solar concentrating elements arranged in a tracking system in accordance with the preferred embodiment of the present invention;

Fig. 2A: Is a schematic isometric bottom view of a solar energy concentrating system showing the brackets arranged on an alignment bar (AB); Fig. 2B: Is a schematic isometric view of one row of concentrating elements corresponding to one AB and associated concentrating elements;

Fig. 2C: Shows one bracket supporting a solar converting element

Fig. 2D shows an AB, emphasizing its main rotation axis;

Fig. 3 is a schematic description of a greenhouse utilizing the solar energy collecting system of the invention;

Fig. 4 is a schematic layout of an exemplary system using fibers for solar energy collection , in accordance with some embodiments of the invention;

Fig. 5 is a schematic layout of an exemplary system using fibers and direct collecting of solar energy , in accordance with some embodiments of the invention.

SUMMARY OF THE PRESENT INVENTION

In accordance with a preferred embodiment of the present invention a solar tracking radiation concentrating system includes an optical element, preferably a spherical lens, capable of imaging the sun onto a two dimensional image formation area. One or more solar cells are used for converting the solar energy into electrical or some other form of useful energy. A sun position detector is used for tracking the sun's location. A tracking apparatus is used for placing the solar cell in the image formation area, to coincide with the sun's ever changing image location. Furthermore, according to a preferred embodiment of the present invention, the system further includes a three dimensional tracking device that updates the position of the solar cells to coincide with the solar images, formed by the spherical lenses. One or more motors are used for moving the solar cells to achieve efficient sun tracking. Electronic and computing module is used for controlling the motors, and a sun position detector means is used for detecting the suns location in respect of the solar cells. Furthermore, in accordance with another aspect of present invention, the arrays of tracking optical concentrating elements are used as elements of a super - array covering a large area, for example, a roof covered by one or more two dimensional lens arrays forming a see- through roofing or window, which removes the direct radiation of the sun for creating electrical energy. Furthermore in accordance with another preferred embodiment of present invention, the solar energy produced by the see-through roof is further used to produce water from water condensation or from other sources. Furthermore, in accordance with another preferred embodiment of present invention, the two dimensional see-through roof and water source are used to create a self sustained green house, in which the intense direct sun illumination is removed and its energy is used to support other greenhouse needs. Furthermore, in accordance with another preferred embodiment of the present invention, the solar cells are replaced by optical light guides further used to transfer solar light for illumination or other general purposes.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In accordance with the present invention, a transparent concentrating spherical lens is equipped with a movable solar cell for tracking the focussed sun's rays. An isometric top view of an energy solar tracker and concentrator system in accordance with the preferred embodiment of the present invention is described in Fig. 1A to which reference is now made. Solar radiation from the direction of the sun is designated by arrows 10. Solar tracker and concentrator system 12 includes a plurality of spherical lens elements such as lens 14 arranged in a two dimensional array, each one used for focusing solar radiation coming substantially in the direction of arrows 10. The sun's position is detected by a detector means such as position sensitive detecting (PSD) 16. An example of such a device is Hamamatsu solid state division, position sensitive detecting (PSD) product. The solar positional information issued by detector 16 is provided to a controller, not shown, for further data processing. Output signals of the controller are used for controlling one or more positioning motors . Referring now to Fig. 1B, a bottom -side -up view of the solar tracker and concentrator system is depicted, showing bracket such as bracket 18 associated each with a respective spherical lens element. Spherical lens elements 14 are used for focusing solar radiation, projecting the energy onto solar cells such as solar cell 20. In Figs 2A - D to which reference is now made, several mechanical aspects of the tracking mechanism of the invention are described. In Fig. 2A, an array of spherical lenses such as lens 40 is described schematically, showing the underside of the array, i.e. the side looking away from the sun. Housing element 42 supports position detector 16. It also maintains the axes of alignment bars, such as axis 44 of alignment bar (AB) 46 mutually in parallel. Onto AB 44 are rotatably connected pulleys such as bracket pulley 48, and driving pulley 52. Driving pulley 52 is driven by a motor, turning a belt or a chain (not shown) that turns all bracket pulleys such as bracket pulley 48, rotatably installed and aligned on AB 46. AB 46 represents a plurality of ABs in the array, all configured in a parallel alignment. In Fig. 2B, AB 46 and associated elements is shown in more detail. Electrical motor 56 drives pulley 52. An electronic controller not shown, determines how much motor 56 turns either to the right or left. Pulleys 48 on AB 46 are turned simultaneously by pulley 52 and the associated belt/chain, not shown. All pulleys swivel around a pivot such as pivot 58 having an axis of rotation as exemplified by dashed line 60. AB 46 rotates round a main axis of rotation as designated by dashed line 62. Except for a driving pulley, in this example pulley 52, all other pulleys are connected to respective brackets such as bracket 18, onto which a solar cell 20. In Fig. 2C bracket 18 is described schematically showing pulley 70 associated with the bracket. The pulley is attached firmly to the bracket, so that the bracket turns with the pulley as it turns. The free end of the bracket supports solar cell 20, turning it around a sector of an associated lens. The perimeter of the pulley is typically notched or roughened or toothed in order to enhance the grip of the driving belt/chain. In Fig. 2D, axis of rotation 62 of AB 46 is shown, emphasizing the other axial movement of the entire set of brackets associated with the AB as they follow the outlines of the spherical lenses (only one lense shown). An electrical motor drives AB. This motor is controlled by the controller mentioned above or another one, in order to determine the extent and direction of movement of the ABs in the array. All ABs of the array are typically rotated simultaneously by one or more motors. As can be seen in Fig. 2A to which reference is now made again the plurality of axes 44 , protrude out of housing element 42. By using a system of pulleys over the axes ends and a belt/chain motor arrangement, all the AB pulleys can be turned together. In one embodiment of the present invention a separate motor is required for rotating the plurality of brackets associated with each AB.

The simultaneous movements of each solar cell cause each solar cell of the array to view the sun's focal point around its respective spherical lens at the same steric angle. . A schematic drawing of a solar powered green house in accordance with the present invention is described in Fig. 3 to which reference is now made. Green house roof 100 of a green house is made of transparent focusing elements. Direct incident solar radiation 102 is focused onto one or more solar arrays 104 each containing a mechanism for simultaneous movement of solar cells that track the focussed sun radiation in each spherical lens as described above. The produced electric energy is converted and stored by power management system 108. This produced electrical energy is used to power the water condensation system 110. The condensation is done preferably when the ambient conditions such as temperature and humidity are best suited for water condensation. The produced water is used for irrigation needs of the green house. The described solar roof is capable of blocking the direct solar radiation which is absorbed by the solar arrays and to transmit the scattered sky radiation 112 which is used for illumination necessary for plant growth.

In accordance with some embodiment of the present invention one or more optical fibres are used for collecting the solar energy concentrated at the focal plane of the spherical lenses elements. An example of fibres based solar collection system is described in Fig. 4 to which reference is now made. Fibers collection system 300 includes solar radiation focusing elements 302, such as spherical lens. Fiber input ends 304 are capable of moving in three dimensions while tracking the position of the focused solar light. The Outlet of bundle 306, is used for combining radiation of multiple fibers input ends 304. The output bundle can be used for illumination or other useful purposes such as electricity generation.

A Schematic layout combining solar power and illumination system is described in Fig. 5 to which reference is now made. The direct solar radiation 400 is focused by focusing elements 402 onto a solar cells 404. These solar cells are capable of absorbing fully or partially the solar energy in the invisible part of the spectrum and transmit the visible radiation which is further focused onto the optical fibers ends 406. The electric energy produced by the solar cells is transferred to power management module 408 using stationary power cells which convert and stores the electric energy for further utilization. The bundle of output ends of fibers 410 is used for illumination or other useful purposes.

A Schematic layout of a fiber delivered solar energy system is described in Fig. 6 to which reference is now made. The direct solar radiation 400 is focused by the focusing elements 402 onto input ends 406 of optical fibers . These fibers are mounted on a two dimensional array capable of moving in three dimensions while tracking the position of the focused solar light. The output ends of the optical fibers are coupled to solar cell 504, which produces electric power delivered to power control unit 506.

BENEFITS OF THE PRESENT INVENTION

The present invention resolves the problems of solar tracking by simultaneously moving a set of solar cells in the solar rays concentration area. The novel technique is based on an optical element concentrating the solar energy and a relatively small solar cell following the focal planes of the concentrating lenses focussing the solar energy. The device built according to the invention is capable of performing efficient direct solar energy collection preferably without obstructing ambient (sky scattered) light.

The implementation of the present invention is capable of creating transparent, cost-effective building elements that can efficiently convert solar energy to electricity and useful light. The invention enables the creation of a simple and reliable system for devices such as green houses, see- through solar windows, optical fiber illuminators and other related devices.

Claims

1. A solar energy collecting and concentrating system comprising:

• at least one optical concentrating lens, for concentrating said solar energy and imaging said energy onto a two dimensional image formation area;

• a solar cell for converting said concentrated energy into another form of useful energy; • a sun position detector capable of issuing data relating to the sun's momentary location;

• a tracking subsystem consisting of a first and a second rotating means capable of placing a free bracket end in said image formation area to coincide with the suns momentary image location, and

• a solar cell disposed on said free bracket end . .

2. A solar energy collecting and concentrating system as in claim 1 , wherein said at least one optical element is a spherical lens.

3. A solar energy collecting and concentrating system as in claim 1 , wherein said solar cell is capable of converting the solar energy to electrical energy.

4. A solar energy collecting and concentrating system as in claim 1 , wherein a planar array of concentrating elements are sun trackable by a tracking subsystem comprising: • a plurality of alignment bars (ABs) all positioned in parallel, wherein said ABs are rotatable around a main axis of rotation, said axis maintained by a housing element;

• sets of brackets, each set aligned in parallel on a respective AB, wherein one side of each of said brackets is rotatably attached to said AB, and firmly connected to a pulley;

• solar cells positioned on the free end of each of said brackets, wherein said cells are capable of absorbing the energy focussed by said concentrating elements and converting said energy to other types of energy ; • motor means capable of moving said pulleys to rotate said brackets supporting solar cells using a belt/chain means, to bring said solar cells to coincide with the focussed sun ray by each one of said concentrating elements;

• a position detector means to provide suns location and, • electronic and computing means to provide controlling signals to said motors.

5. A solar energy collecting and concentrating system as in claim 4 wherein a plurality of such planar arrays are used to produce a super - array of a large area, comprising of multiple two dimensional lens arrays connected together to create a see- through roofing or window, wherein the direct sun's direct radiation is removed and used to create electrical energy.

6. A energy collecting and concentrating system as in claim 5 wherein, the solar energy produced by said see- through roof is further used to produce water from air condensation.

7. A energy collecting and concentrating system as in claims 1 and 4, wherein optical light guides are positioned in the image forming area of said concentrating elements, further used to transfer a potion of said solar light for illumination or other general purposes.

8. A solar energy collecting and concentrating system comprising:

• an optical concentrating lens, for concentrating the sun energy and imaging said energy onto a two dimensional image formation area; • an optical light guide for collecting said energy from said formation area;

• a sun position detector capable of tracking the sun's momentary location; • a tracking subsystem capable of placing said solar cell in said image formation area to coincide with the suns momentary image location, and wherein said light guides are used to transfer said solar energy to other locations.

9. A solar energy collecting and concentrating system as in claim 8, wherein said optical light guides are coupled to a stationary solar cell in order to produce electric energy.