A method of utilizing solar radiation as a solar radiation source moves throughout the day includes providing a deformable surface having a pair of opposing edges and supporting the opposing edges of the deformable surface with a pair of flexible members. The method also includes imparting a curvature on the deformable surface to cause incident rays to be coincident with the normal axis of the deformable surface. The method further includes changing the curvature of the deformable surface as the solar radiation source moves throughout the day, such that the curvature corresponds to a location of the solar radiation source.

Not applicable

Not Applicable

TECHNICAL FIELD

The nature of the invention relates to tracking devices of electromagnetic radiation, and especially as a system where solar radiation may be concentrated, redirected or utilized as in systems such as, but not limited to, concentrating solar power, photovoltaic power or concentrating photovoltaic power.

BACKGROUND ART

The present invention pertains generally to optical/mechanical systems designed to utilize electromagnetic radiation. Specifically, the system concentrates, redirects or utilizes solar radiation for useful purposes.

Many patents exist which seek to decrease cost and complexity of solar power systems.

It is therefore an object of xe invention to provide a solar power system, or portion thereof, that is economical to construct.

It is another object of the invention to provide a solar power system that has a large collecting area.

It is a further object of the invention to concentrate obliquely incident solar radiation falling upon a ganged heliostat reflector.

It is a further object of the invention to align multiple solar panels so that the panel's normal axes are parallel to the solar radiation falling upon the solar panels.

It is a further object of the invention to demonstrate economical deployment in or on rough terrain.

DESCRIPTION OF RELATED ART

Patent Numbers and Application numbers:

RELATED LITERATURE

SUMMARY OF THE INVENTION

In one embodiment, a method is provided for concentrating solar radiation from a moving solar radiation source onto a separately disposed receiver as the moving solar radiation source moves throughout the day. The method includes providing a deformable reflective surface having a pair of opposing edges and supporting the opposing edges of the deformable reflective surface with a pair of flexible members. The method further includes imparting a curvature on the deformable reflective surface to reflect rays from the moving solar radiation source to a receiver, and to focus the reflected rays to reduce astigmatism caused by the incidence of solar radiation upon the deformable surface. The method also includes changing the curvature of the deformable reflective surface as the moving solar radiation source moves throughout the day. The changing steps are taken from the group consisting of (a) orienting the opposing edges of the deformable reflective surface at differing rotational orientations, (b) individually tensioning the flexible members supporting the opposing edges of the deformable surface at different tensions and (c) orienting the opposing edges of the deformable reflective surface at differing rotational orientations and individually tensioning the flexible members supporting the opposing edges of the deformable surface at different tensions.

In another embodiment, a method of utilizing solar radiation as a solar radiation source moves throughout the day includes providing a deformable surface having a pair of opposing edges and supporting the opposing edges of the deformable surface with a pair of flexible members. The method also includes imparting a curvature on the deformable surface to cause incident rays to be coincident with the normal axis of the deformable surface. The method further includes changing the curvature of the deformable surface as the solar radiation source moves throughout the day, such that the curvature corresponds to a location of the solar radiation source. The shaping steps are taken from the group consisting of (a) orienting the opposing edges of the deformable surface at differing rotational orientations. (b) individually tensioning the flexible members supporting the opposing edges of the deformable surface at different tensions, and (c) orienting the opposing edges of the deformable surface at differing rotational orientations and individually tensioning the flexible members supporting the opposing edges of the deformable surface at different tensions, these orientations and tensions changing throughout the day to correspond to the solar radiation source.

In yet another embodiment, a system for utilizing solar radiation includes a deformable surface having a pair of opposing edges and a pair of flexible members supporting the opposing edges of the deformable surface, each flexible member having a first end and a second end. The system also includes a first hub having a first tensioning mechanism connected to the first ends of the pair of flexible members, the first hub being rotatable about an axis substantially parallel to the pair of flexible members. The system further includes a second hub having a second tensioning mechanism connected to the second ends of the pair of flexible members, the first hub being rotatable about an axis substantially parallel to the pair of flexible members. The first and second hub are configured to change a curvature of the deformable surface by rotating about the axis substantially parallel to the pair of flexible members. The first and second tensioning mechanisms are configured to change a curvature of the deformable surface by adjusting a tension of at least one of the flexible members.

DETAILED DESCRIPTION

FIGS. 1-4illustrate one embodiment of a ganged heliostat. Multiple components act in concert to shape a reflective surface so as to concentrate obliquely incident solar radiation.

In one embodiment the ganged heliostat may shape a reflective surface so as to concentrate obliquely incident solar radiation at a fixed receiver diurnally, or the same mechanism or portion thereof, may orient multiple solar panels so that each panel face is perpendicular the incident radiation diurnally. The solar panels may redirect radiation to be utilized elsewhere. The reflective surface may be a continuous flexible sheet, or a plurality of flat reflectors. The reflective surface is supported by flexible members such as cables. The members would hang freely between supports located at, or near the member's endpoints. The overall surface generated by the flexible members would be a portion of a catenary of revolution or catenoid laying principally in the horizontal with the reflective surface facing up. A shallow catenoid approximates the surface of a sphere. Obliquely incident radiation striking a sphere-like reflector is concentrated at the astigmatic foci. Deformation of the flexible members changes the orientation and shape of the reflective surface. Deformation of the flexible members may be accomplished by varying the flexible member tension which may be combined with rotation of the flexible member endpoints about an axis principally horizontal, parallel to and in line with the flexible members. Additionally, each facet of the reflective surface may rotate about an axis in line with the facet and perpendicular to the flexible members.

For concentrating solar power applications, the deformation is such that radiation reflected is concentrated at the center of a chosen astigmatic focal zone. Essentially the deformation imposes a crossed cylinder warp, or toric contour on the reflective surface, correcting astigmatic aberration. Rotational variation of individual reflectors improves system accuracy and concentration level. The reflecting surface concentrates solar radiation at the receiver. The receiver may be fixed and placed to receive the concentrated radiation. The receiver may be tracking, such that the receiver moves to always be at the focal zone(s) as it tracks the reflected solar radiation through the day. By these means a cost efficient and large ganged heliostat may be achieved. A plurality of the ganged heliostats may concentrate solar radiation in unison. The plurality of ganged heliostats may be arranged end to end, side by side or both. Enabling the sharing of system infrastructure and reducing cost. The plurality of ganged heliostats arranged both end to end and side by side may have application in concentrating solar power (CSP) power tower style systems. The plurality of ganged heliostats arranged primarily side by side may concentrate collectively to a line focus having applications in CSP trough style systems.

For photovoltaic or concentrating photovoltaic applications each of the individual heliostats of the ganged heliostat may oriented by the invention so that all individual heliostat surfaces are simultaneously parallel to each other and perpendicular to the radiation source. Continued deformation by the invention may maintain this orientation as the radiation source moves throughout the day. For photovoltaic (PV) applications less infrastructure may be used due to relaxed requirements of orientation accuracy while still achieving nearly all the performance benefits of fully tracking dual axis style systems.

Another application of the above described orientation, where each heliostat surface is simultaneously parallel to each other and perpendicular to the radiation source, has main heliostat surfaces which are reflective and concave in shape. These concave reflectors have secondary optics, such as a convex reflector, placed near each of the concave reflector's focal area where both concave reflector and secondary optic share a common normal axis. Given above, that this normal axis may coincide with the radiation source, each heliostat of the ganged heliostat would produce a collimated beam output. This output may be steered by a tertiary reflector, one per heliostat, to redirect the output to a receiver. The receiver may be at or near ground level. Although more complex, such a system would have benefits of eliminating the need for a receiver tower and being capable of a narrow input angle into the receiver reducing radiative loss.

Applications above describing the utilization of flat reflectors should not be construed as limiting. Reflectors may be flat or reflectors could be a plurality of flat reflectors held in a reflector cell designed to angle the flat reflectors so that a relatively shallow concave reflector is approximated. The angle of this canting being optimized for system size and distance to receiver so that concentration is further increased.

Referring toFIG. 3. support posts1are firmly attached to the earth or ballasted for rigidity. Support posts1carry hubs7and11. Hubs7and11may rotate about rotational axis8. Hubs7and11may be internally or externally actuated. External actuators9are depicted. Hub7carries cable tensioning mechanism6, here depicted as two linear actuators where dashed lines5show travel of the cable tensioning mechanism6. One end of the cables3, or dashed line cable4, attach to cable tensioning mechanism6. Cables3depicts tauter cables than cables4. The cables3or cables4carry the deformable surface. The other end of cables3or cables4attach to block2which is attached to hub11. Grade10is shown for reference.

Referring toFIG. 4, support posts4are firmly attached to the earth or ballasted for rigidity. Support posts4carry hubs3and9. Hubs3and9may rotate about a rotational axis parallel to the long axis of the invention to and coincident with the rotational axes of hubs3and9. Hubs3and9may be internally or externally actuated. One external actuator10is depicted. Plate5attaches cable tensioning mechanism2to hub3. Cable tensioning mechanism2, here depicted as two linear actuators where dashed lines6show travel of the cable tensioning mechanism2. Proximate ends of cable1and cable7attach to cable tensioning mechanism2. The opposing ends of cable1and cable7attach to hub9. Cable1and cable7carry solar panels8, twenty-four of which are shown. Each of the solar panels8may rotate about an axis perpendicular to and in a line with cable1and cable7. The rotation of the solar panels8is detailed inFIG. 2.

Independent variation of cable tension, hub rotational orientation and solar panel rotation, or a partial combination thereof, imposes a toric shape to the surface defined by the solar panels. Appropriate toric shapes may allow either obliquely incident radiation reflected by the solar panels to be concentrated at a separate and fixed receiver, or orient all solar panels such that each panel's normal axis is coincident with radiation source so as to enhance photovoltaic performance or to redirect the radiation for use elsewhere. A ganged heliostat as described herein allows for utilization of solar energy with reduced cost and infrastructure. Control means may be open or closed loop in method. Control may be of a CPU logic circuit to maximize performance.

Referring toFIG. 2, cables1support a plurality of solar panels3, one of which is shown, by means of panel support bar2. Panel support bar2attaches to cables1, where attachment may be fixed or allow limited movement such as a cable passing through a tube where cable diameter is less than tube diameter. Solar panels3may rotate about rotational axis5. Actuation of the solar panels3is accomplished by actuator4. Cables1terminate to cable eye7and are held in place by swage block6. Retaining pin8passes through cable eye7and cable tension mechanism10and is kept in place with cotter pins9.

Referring toFIG. 1, Cables1attach to cable tensioning mechanism2. Dashed lines and double headed arrow describe action of cable tensioning mechanism2. Cable tensioning mechanism2is comprised of two actuators, one per cable to vary cable tension independently. Cable tensioning mechanism2′s actuators attach to plate3which attaches to hub5. Hub5allows plate3and cable tensioning mechanism2to rotate about rotational axis4. The non-rotating end of hub5is attached to post6.

Accordingly, it is to he understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention. The scope of the invention should not be construed as limited to solar applications.

INDUSTRIAL APPLICABILITY

The invention described herein has applications in solar thermal power, Concentrating Solar Power (CSP), Solar Photovoltaic and Concentrating Photovoltaic power (CPV). Given a CPV or CSP plant's use of many thousands of individual heliostats, substantial cost savings can be gained by use of the described invention. The invention eliminates the needs for each panel to have a support post of some type. The invention eliminates the need for a dual axis drive for each heliostat.

For Photovoltaic (PV) applications the reduced costs are likely to be more pronounced given the lower accuracy requirements for PV, as opposed to CSP or CPV. Elimination of some elements of the inventions degrees of freedom can still provide a ganged heliostat with accuracy acceptable to typical fully tracking PV applications at a further reduced cost structure.

The invention, a cost effective and scalable heliostat, likely has other applications such as but not limited to solar desalinization and astronomy.