HIGHLY EFFICIENT SOLAR ARRAYS

• US 20120204935A1
• Filed: 08/10/2011
• Published: 08/16/2012
• Est. Priority Date: 02/23/2010
• Status: Active Grant

• Current Assignee: Spectrum Solar, LLC
• Original Assignee: Tenksolar, Inc.
• Inventors: Meyer, Dallas W., Berg, Lowell J., Stover, Lance E., Dodd, Orville D., Murnan, Thomas L.
• Granted Patent: US 8,829,330 B2
• Time in Patent Office: Days
• US Class Current: 136/246
• CPC Class Codes: F24S 2020/14 Stepped arrangements, e.g. in parallel planes, without module overlapping
• CPC Class Codes: F24S 2020/16 Preventing shading effects
• CPC Class Codes: F24S 2025/803 having a central web, e.g. I-shaped, inverted T- shaped
• CPC Class Codes: F24S 2025/807 having undercut grooves
• CPC Class Codes: F24S 23/77 with flat reflective plates
• CPC Class Codes: F24S 25/16 Arrangement of interconnected standing structures; Standing structures having separate supporting portions for adjacent modules
• CPC Class Codes: F24S 25/35 by means of profiles with a cross-section defining separate supporting portions for adjacent modules
• CPC Class Codes: F24S 25/37 forming coplanar grids comprising longitudinal and transversal profiles
• CPC Class Codes: F24S 25/632 Side connectors; Base connectors
• CPC Class Codes: F24S 25/65 for coupling adjacent supporting elements, e.g. for connecting profiles together
• CPC Class Codes: F24S 25/70 with means for adjusting the final position or orientation of supporting elements in relation to each other or to a mounting surface; with means for compensating mounting tolerances
• CPC Class Codes: F24S 40/80 Accommodating differential expansion of solar collector elements
• CPC Class Codes: F24S 40/85 Arrangements for protecting solar collectors against adverse weather conditions F24S40/10 takes precedence
• CPC Class Codes: G02B 7/183 specially adapted for very large mirrors, e.g. for astronomy, or solar concentrators
• CPC Class Codes: H02S 20/22 specially adapted for buildings
• CPC Class Codes: H02S 40/22 Light-reflecting or light-concentrating means directly associated with the PV cell or integrated with the PV cell H01L31/054
• CPC Class Codes: Y02B 10/10 Photovoltaic [PV]
• CPC Class Codes: Y02B 10/20 Solar thermal
• CPC Class Codes: Y02E 10/47 Mountings or tracking
• CPC Class Codes: Y02E 10/52 PV systems with concentrators

Abstract

In an example, a solar energy system includes multiple PV modules, multiple reflectors, and a racking assembly. Each of the reflectors is positioned opposite a corresponding one of the PV modules. The racking assembly mechanically interconnects the PV modules and the reflectors to form an interconnected system. The racking assembly defines gaps within the racking assembly and between adjacent PV modules and reflectors. The interconnected system includes multiple contact points associated with the gaps. The gaps and contact points configure the interconnected system to accommodate surface unevenness of an installation surface up to a predetermined surface unevenness.

Claims

1. A solar energy system, comprising:

a plurality of photovoltaic modules;

a plurality of reflectors, each of the plurality of reflectors positioned opposite a corresponding one of the plurality of photovoltaic modules; and

a racking assembly mechanically interconnecting the plurality of photovoltaic modules and the plurality of reflectors to form an interconnected system;

wherein;

the racking assembly defines gaps within the racking assembly and between adjacent photovoltaic modules and reflectors;

the interconnected system includes a plurality of contact points associated with the gaps;

the gaps and contact points configure the interconnected system to accommodate surface unevenness of an installation surface up to a predetermined surface unevenness.

2. The solar energy system of claim 1, wherein the predetermined surface unevenness is in a range from one eighth of an inch per linear foot to one half of an inch per linear foot.

3. The solar energy system of claim 1, wherein the interconnected system has a nonlinear resistive force versus displacement profile.

4. The solar energy system of claim 3, wherein the interconnected system is substantially compliant for displacements in a direction orthogonal to the installation surface up to a predetermined threshold and substantially non-compliant for displacements greater than the predetermined threshold.

5. The solar energy system of claim 1, wherein the photovoltaic modules and reflectors are arranged in adjacent rows and the racking assembly comprises:

a plurality of rails arranged orthogonally to and beneath the adjacent rows; and

a plurality of fins that interconnect the photovoltaic modules and the reflectors to the rails.

6. The solar energy system of claim 1, wherein:

the adjacent rows include reflector rows interposed between module rows;

each reflector row includes multiple reflectors;

each module row includes multiple photovoltaic modules;

each photovoltaic module and each reflector has two lower corners, each lower corner being connected to the racking assembly through a corresponding fin;

each photovoltaic module has two upper corners, each connected to a respective one of two upper corners of a corresponding reflector positioned behind the photovoltaic module; and

adjacent lower corners of adjacent photovoltaic modules within each module row and of adjacent reflectors within each reflector row are connected to each other through a corresponding one of the fins.

7. The solar energy system of claim 6, wherein:

the fins define a module-to-module gap between the adjacent photovoltaic modules within each module row and a reflector-to-reflector gap between the adjacent reflectors within each reflector row;

sides of each of the adjacent photovoltaic modules and adjacent reflectors on opposing sides of each module-to-module gap or reflector-to-reflector gap include the contact points associated with the module-to-module gap or reflector-to-reflector gap;

each rail has a top defining a longitudinal channel;

each fin has a base received within the longitudinal channel;

a longitudinal gap is defined between the base of each fin and a bottom of the longitudinal channel of each rail;

a bottom of each longitudinal channel and a bottom of each base include contact points associated with each longitudinal gap.

8. The solar energy system of claim 7, wherein:

the plurality of rails includes a plurality of rail columns;

within each rail column, multiple rails are longitudinally aligned and connected end-to-end to each other;

a rail-to-rail gap is defined between adjacent longitudinally-connected rails; and

ends of adjacent longitudinally-connected rails on opposing sides of each rail-to-rail gap include contact points associated with each rail-to-rail gap.

9. The solar energy system of claim 8, wherein one or more of the module-to-module gaps, reflector-to-reflector gaps, longitudinal gaps or rail-to-rail gaps allow the components of the interconnected system to accommodate in-plane and out-of-plane displacement relative to one another until the contact points associated with a corresponding module-to-module gap, reflector-to-reflector-gap, longitudinal gap or rail-to-rail gap come in contact with each other;

wherein a stiffness of the interconnected system is much greater when the contact points are in contact with each other than when the contact points are not in contact with each other.

10. The solar energy system of claim 5, wherein the racking assembly further comprises a plurality of compliant pads, each compliant pad being positioned between a rail and the installation surface, wherein a coefficient of friction between the compliant pads and the installation surface is greater than a coefficient of friction between the rails and the installation surface.

11. The solar energy system of claim 10, wherein each of the compliant pads comprises expanded polyethylene having a thickness in a range of 0.5 inches to 2 inches.

12. The solar energy system of claim 11, wherein each of the compliant pads further comprises a bottom layer including at least one of butyl rubber, ethylene propylene diene Monomer (EPDM) rubber, or polyurethane adhesive, the bottom layer having a thickness in a range of 0.05 to 0.5 inches.

13. The solar energy system of claim 10, wherein each of the compliant pads comprises ethylene propylene diene Monomor (EPDM) rubber having a thickness in a range of 0.1 inches to 1 inch.

14. The solar energy system of claim 5, wherein the racking assembly is configured to permit individual removal or positional adjustment of any one of the photovoltaic modules or reflectors without removing or otherwise supporting any of the other photovoltaic modules or reflectors during the removal or positional adjustment.

15. The solar energy system of claim 14, wherein the reflectors are configured to be individually adjusted at least twice annually between a first position and a second position, the reflectors being positioned at a first angle relative to horizontal in the first position and a second angle relative to horizontal in the second position, the second angle being different than the first angle.

16. The solar energy system of claim 15, wherein:

each photovoltaic module has two upper corners, each connected to a respective one of two upper corners of a corresponding reflector positioned behind the photovoltaic module such that each corresponding reflector can rotate, relative to the photovoltaic module, about a first axis of rotation that is parallel to a top edge of the photovoltaic module and to a top edge of the corresponding reflector;

each lower corner of each photovoltaic module is coupled to a corresponding fin;

each lower corner of each reflector is coupled through a corresponding connector to the same fin as the corresponding lower corner of the photovoltaic module positioned opposite the reflector; and

at least one of;

each fin defines a slot in which a corresponding connector can travel between a first endpoint corresponding to the first position and a second endpoint corresponding to the second position, a corresponding reflector rotating about a corresponding first axis of rotation when the corresponding connector travels between corresponding first and second endpoints in a slot of a corresponding fin;

each connector is configured to support a bottom edge of a corresponding reflector at a first predetermined location relative to a corresponding fin when in the first position and at a second predetermined location relative to the corresponding fin when in the second position, wherein the first and second predetermined locations are configured to prevent the corresponding fin from shadowing the corresponding reflector in morning or afternoon lighting conditions;

or

each connector is rotatably coupled to a corresponding fin and is rotatable between a first connector position in which the connector is configured to support a corresponding reflector in the first position, and a second connector position in which the connector is configured to support the corresponding reflector in the second position.

17. The solar energy system of claim 5, wherein a length of each rail is in a range between 15 and 30 feet.

18. The solar energy system of claim 5, further comprising a rainwater collection subsystem.

19. The solar energy system of claim 18, wherein the photovoltaic modules and reflectors are positioned such that top surfaces thereof are at one or more angles relative to horizontal, and wherein the rainwater collection subsystem comprises:

an extruded drip gutter extending from a bottom edge of each photovoltaic module and of each reflector, the extruded drip gutter configured to collect rainwater that runs down the surface of the corresponding photovoltaic module or reflector and to channel the collected rainwater towards one or both ends of the extruded drip gutter, one or both ends of the extruded drip gutter being open to expel the collected rainwater therefrom;

edge extensions extending upwards from a base of each rail to define rail channels on opposing sides of each rail, the rail channels being positioned beneath ends of the extruded drip gutters such that expelled rainwater is captured in the rail channels; and

one or more storage reservoirs in fluid communication with the rail channels, the one or more storage reservoirs being configured to receive and store the rainwater captured by the rail channels.

20. The solar energy system of claim 1, wherein:

each of the photovoltaic modules and reflectors includes a frame;

each frame comprises two side members positioned on opposing sides of a corresponding photovoltaic module or reflector;

each side member for each reflector frame has a double-wall-box construction including an inner box aligned lengthwise side-by-side with an outer box along at least most of the length of each side member, one side of each box being a common wall shared between the inner and outer boxes;

each side member for each module frame has a single-wall-box construction;

each side member has a length greater than a length of the corresponding photovoltaic module or reflector and is arranged such that top and bottom ends of each side member respectively extend beyond upper and lower edges of a corresponding photovoltaic module or reflector;

the outer wall box is absent from the top end of each side member in each reflector frame; and

the top end of each of two side members in a frame of each photovoltaic module is removably coupled to the top end of each of two side members in a frame of a corresponding reflector positioned behind the photovoltaic module.

21. The solar energy system of claim 20, wherein:

the side members in each photovoltaic module frame and the racking assembly are electrically conductive; and

the bottom end of each side member in each photovoltaic module frame is mechanically and electrically coupled directly to the racking assembly to provide a direct grounding connecting from each photovoltaic module to the racking assembly.

22. The solar energy system of claim 21, further comprising at least one of:

a plurality of star washers, each star washer positioned between the bottom end of a corresponding side member in a corresponding photovoltaic module frame and a portion of the racking assembly to which the bottom end is attached, each star washer being configured to electrically couple the bottom end of the corresponding side member in the corresponding photovoltaic module frame to the corresponding portion of the racking assembly;

or

a plurality of cam locking devices, each configured to mechanically and electrically couple the bottom end of the corresponding side member in the corresponding photovoltaic module frame to the racking assembly.

23. The solar energy system of claim 20, wherein the bottom end of each side member in each reflector frame defines an L-shaped slot, and wherein the top and bottom end of each side member in each module frame defines an L-shaped slot.

24. The solar energy system of claim 23, wherein:

each reflector frame further comprises two plastic inserts, each plastic insert positioned in the outer box at the bottom end of a corresponding side member;

each plastic insert is configured to prevent the outer box of the bottom end of the corresponding side member from being crushed;

the bottom end of the corresponding side member of a corresponding reflector frame is configured to be coupled to a fin of the racking assembly by a corresponding connector; and

each plastic insert is configured to retain the corresponding connector in a particular region of the L-shaped slot such that any loads transferred to or from the corresponding reflector frame through the corresponding connector are transferred directly between the bottom end of the corresponding side member and the corresponding connector.

25. A reflector configured to be implemented in a solar energy system, the reflector comprising:

a reflective sheet configured to reflect light having wavelengths within a reflectance spectrum of the reflective sheet; and

a frame supporting the reflective sheet, the frame including two side members positioned at opposing sides of the reflective sheet;

wherein;

each side member has a length greater than a length of the reflective sheet and is arranged such that top and bottom portions of the side member respectively extend beyond upper and lower ends of the reflective sheet; and

each side member has a double-wall-box construction including an inner box connected lengthwise side-by-side with an outer box along at least most of the length of each side member, one side of each box being a common wall shared between the inner and outer boxes that separates the inner box from the outer box.

26. The reflector of claim 25, wherein:

each side member defines a slot extending along at least most of the length of the side member and in which is received a lengthwise edge portion of the reflective sheet;

or

each side member includes a substantially flat surface extending the length of the side member to which a back side of the reflective sheet along a corresponding side of the reflective sheet is adhesively coupled.

27. The reflector of claim 25, wherein the frame further comprises two support members extending widthwise between the two side members and positioned behind the reflective sheet.

28. The reflector of claim 27, wherein each support member includes a cross-sectional shape normal to a length of each support member, the cross-sectional shape being characterized by:

a base member having a first end and a second end opposing the first end;

a first arc connected to the first end and a second arc connected to the second end, wherein each arc includes a first endpoint, a second endpoint and a midpoint located along the arc halfway between the two endpoints, each arc being connected to a corresponding end of the base member at the midpoint of the arc;

a leg pair connected to each arc, each leg pair including a first leg connected to the first endpoint of the corresponding arc and a second leg connected to the second endpoint of the corresponding arc; and

a foot pair connected to each leg pair, each foot pair including a first foot connected to the first leg of the corresponding leg pair and a second foot connected to the second leg of the corresponding leg pair, wherein the first foot and second foot in each foot pair are collinear.

29. The reflector of claim 28, wherein each arc defines a semi-circular cavity, the reflector further comprising a plurality of pan head screws coupling the side members to the support member, each pan head screw being assembled into the reflector such that:

the pan head screw is inserted completely through two oversized and axially aligned holes defined in an outer wall and the common wall of the corresponding side member;

a threaded shaft of the pan head screw is inserted through a hole defined in an inner wall of the corresponding side member that is axially aligned with the two oversized and axially aligned holes; and

the threaded shaft is threaded into a corresponding semi-circular cavity of a corresponding support member until a head portion of the pan head screw rests against an inside surface of the inner wall of the corresponding side member and an end of the corresponding support member is retained against an outside surface of the inner wall of the corresponding side member.

30. The reflector of claim 28, further comprising an adhesive positioned between one of the two foot pairs of the support member and a back side of the reflective sheet and configured to couple the support member to the back side of the reflective sheet.

31. The reflector of claim 25, wherein the reflective sheet has a transmittance spectrum including predetermined wavelengths of visible light such that when the reflector is installed in an overhead structure provided above a particular space, natural lighting having the predetermined wavelengths illuminates the particular space after being transmitted through the reflective sheet.

32. The reflector of claim 31, wherein the natural lighting includes wavelengths of about 400-600 nanometers for certain incident angles.

33. The reflector of claim 25, wherein the reflective sheet comprises a glass substrate and a spectroscopic film comprising a stack of dielectric layers, the spectroscopic film being formed directly on the glass substrate by at least one of direct or reactive sputtering, chemical vapor deposition (CVD), physical vapor deposition, atomic layer deposition (ALD) or plasma-enhanced CVD (PE-CVD).

34. The reflector of claim 33, wherein the spectroscopic film is formed directly on a top surface of the glass substrate or a bottom surface of the glass substrate.

35. The reflector of claim 34, wherein the reflective sheet further comprises at least one of a black absorbing layer, a diffuse reflecting layer, or an aluminum layer.

36. The reflector of claim 25, wherein the side members of the frame are formed by extrusion and include a curvature along their length to cause the reflective sheet to crown.

37. The reflector of claim 25, wherein the reflective sheet includes a layer patterned with a laser, the patterning comprising externally visible advertising information.

38. The reflector of claim 25, wherein the reflective sheet comprises a spectroscopic film configured to reflect light having wavelengths within the reflectance spectrum of the reflective sheet and to transmit light having wavelengths within a transmittance spectrum of the spectroscopic film, the reflective sheet further comprising a diffuse or absorbing film applied behind the spectroscopic film and configured to prevent light transmitted through the spectroscopic film from being transmitted completely through the reflective sheet.

39. A solar energy system, comprising:

a photovoltaic module, wherein;

the photovoltaic module includes a frame along a perimeter of the photovoltaic module;

the frame includes two side members positioned on opposing sides of the photovoltaic module;

each side member has a top end and a bottom end that respectively extend beyond a top edge and a bottom edge of the photovoltaic module; and

each side member has a single-wall-box construction; and

a rod received through a slot in the top end of each of the two side members, the rod being coupled to a vertical installation surface and coupling the photovoltaic module to the vertical installation surface.

40. The solar energy system of claim 39, further comprising a bottom support member extending from the vertical installation surface against a bottom portion of the photovoltaic module, the bottom support member supporting the photovoltaic module at an angle relative to the vertical installation surface.

41. The solar energy system of claim 39, further comprising a base reflector including two protrusions on opposing ends of the same edge of the base reflector, wherein each of the two protrusions extends into a hole in the bottom end of each of the two side members to couple the base reflector to the photovoltaic module.

42. The solar energy system of claim 41, wherein the base reflector comprises a semi-rigid layer and a reflective layer configured to reflect light having wavelengths within a reflectance spectrum of the reflective layer.

43. The solar energy system of claim 42, wherein the semi-rigid layer comprises UV-stabilized polyethylene.

44. The solar energy system of claim 42, wherein the base reflector further comprises a metallic stiffener having the two protrusions integrally formed on opposing ends thereof, a cantilever of the metallic stiffener extending into the semi-rigid layer.

45. The solar energy system of claim 41, wherein the two protrusions define an axis of rotation of the base member and wherein the base member is configured to rotate about the axis of rotation to adjust a relatively angle of the base member to the photovoltaic module.