System and method for converting solar energy to electricity

• US 6,686,533 B2
• Filed: 01/29/2002
• Issued: 02/03/2004
• Est. Priority Date: 01/29/2002
• Status: Active Grant

• Current Assignee: Israel Aerospace Industries Limited (Government of Israel)
• Original Assignee: Israel Aerospace Industries Limited (Government of Israel)
• Inventors: Baum, Avi, Halfon, Moshe, Steinman, Abraham
• Primary Examiner(s): Diamond; Alan
• Application Number:
  US10/060,093
• Publication Number:
  US 20030140960A1
• Time in Patent Office: 735 Days
• Field of Search: 136/244,246 257/432,436,443 250/203.4 438/65,66,80
• US Class Current: 136/244
• CPC Class Codes: F24S 50/20 for tracking
• CPC Class Codes: H01L 31/02021 for solar cells electrical connection means, e.g. junction boxes, specially adapted for structural association with photovoltaic modules H02S40/34
• CPC Class Codes: H01L 31/0521 using a gaseous or a liquid coolant, e.g. air flow ventilation, water circulation
• CPC Class Codes: H01L 31/0543 comprising light concentrating means of the refractive type, e.g. lenses
• CPC Class Codes: H01L 31/0547 comprising light concentrating means of the reflecting type, e.g. parabolic mirrors, concentrators using total internal reflection
• CPC Class Codes: H01L 31/0549 comprising spectrum splitting means, e.g. dichroic mirrors
• CPC Class Codes: H02S 20/32 specially adapted for solar tracking
• CPC Class Codes: Y02E 10/52 PV systems with concentrators

Abstract

Energy converting system including a cell array and a light concentrating unit directing concentrated light at the cell array, the cell array including a plurality of cells, wherein the cells are coupled together according to the flux of the concentrated light which reaches each of the cells.

Claims

1. Energy converting system comprising:

at least one cell array; and

at least one light concentrating unit unevenly directing concentrated light at said at least one cell array, said at least one cell array comprising at least one parallel connected group coupled in parallel within said at least one cell array,

each said parallel connected group comprising at least two series connected groups coupled in series within said parallel connected group;

each said series connected group comprising at least one photovoltaic cell coupled in parallel within said series connected group, each said series connected group having a series group flux value associated therewith, said series group flux value being the sum of flux values incident on the at least one photovoltaic cell of said series connected group,

wherein for each of said at least one parallel connected group, said respective at least two series connected groups are selected such that differences between said selected series connected group series group flux values are minimal.

2. The system according to claim 1, further comprising at least one optical structure made of a transparent material, said optical structure comprising:

a first surface receiving said at least one cell array;

a second surface receiving said concentrated light; and

a two-dimensional array of prismatic bodies located between said first surface and said second surface, wherein each of said prismatic bodies tapers toward said first surface.

3. The system according to claim 2, wherein each of said prismatic bodies diverts said concentrated light which is directed toward a gap between any two of said cells, to said two cells.

4. The system according to claim 2, wherein each of said prismatic bodies diverts the light from a high-flux region which is directed toward at least one of said cells, to other cells adjacent to said at least one cell.

5. The system according to claim 2, herein a plurality of electrical wires coupled with said cells, pass through the grooves formed by every two of said prismatic bodies.

6. The system according to claim 2, wherein a plurality of electrical wires coupled with said cells, pass through the gaps between every two of said cells, toward a bottom portion of said cells.

7. The system according to claim 1, wherein the bottom surface of said at least one cell array is coupled with a cooling compartment, said cooling compartment comprising:

an inlet;

an outlet; and

a plurality of perforated layers having substantially identical shapes and dimensions, wherein said perforated layers are stacked in a direction parallel to said bottom surface, wherein said perforated layers are alternately offset in said direction, thereby forming a plurality of fluid paths, and wherein a cooling fluid flows from said inlet to said outlet, via said fluid paths.

8. The system according to claim 7, wherein the boundary of each of said perforated layers is perforated.

9. The system according to claim 7, wherein an electrical insulator is located between said bottom surface and said cooling compartment.

10. The system according to claim 7, wherein the size of each one of a plurality of perforations in each of said perforated layers, is substantially greater than the distance between every two of said perforations.

11. The system according to claim 1, further comprising:

an ammeter;

a processor; and

a switch fabric coupled with said ammeter, said cells and to said processor, wherein said processor directs said switch fabric to couple said ammeter to each of said cells, disconnectably, thereby measuring the current in each of said cells, wherein said processor processes said measured currents, wherein said processor selects an array architecture, and wherein said processor directs said switch fabric to couple said cells together, according to said selected array architecture.

12. The system according to claim 11, wherein said processor determines a modified array architecture, by processing said measured currents when at least one of said currents changes, and wherein said processor directs said switch fabric to couple said cells together, according to said modified array architecture.

13. The system according to claim 1, further comprising:

a processor;

a plurality of flux meters coupled with said processor, each of said flux meters measuring the flux value of said concentrated light reaching a different one of said cells; and

a switch fabric coupled with said cells, and to said processor, wherein said processor processes said measured flux values, wherein said processor selects an array architecture, and wherein said processor directs said switch fabric to couple said cells together, according to said selected array architecture.

14. The system according to claim 13, wherein said processor determines a modified array architecture, by processing said measured flux values when at least one of said flux values changes, and wherein said processor directs said switch fabric to couple said cells together, according to said modified array architecture.

15. The system according to claim 1, further comprising:

at least one moving mechanism coupled with said at least one light concentrating unit; and

a sun tracking system coupled with said at least one moving mechanism, for directing said at least one moving mechanism to move said at least one light concentrating unit, such that said at least one light concentrating unit tracks the sun.

16. The system according to claim 15, wherein said sun tracking system is selected from the group consisting of:

closed loop; and

open loop.

17. The system according to claim 15, further comprising a processor coupled with said sun tracking system and to at least one detector, wherein said at least one detector detects the flux of said concentrated light reaching each of said cells, wherein said processor processes the values of said flux, and wherein said processor directs said sun tracking system to move said at least one light concentrating unit, such that said flux is maximal.

18. The system according to claim 1, wherein said at least one light concentrating unit is selected from the group consisting of:

lens;

lens assembly;

light guide; and

concave mirror.

19. The system according to claim 18, wherein said concave mirror comprises a plurality of curved reflective plates, wherein a different one of said curved reflective plates directs said concentrated light toward a different region of said at least one cell array.

20. The system according to claim 15, wherein said sun tracking system detects the current generated by each of said cells, and wherein said sun tracking system directs said at least one moving mechanism to move said at least one light concentrating unit, according to said detected currents.

21. The system according to claim 20, wherein said sun tracking system directs said at least one moving mechanism to move said at least one light concentrating unit, by comparing said detected currents with a value.

22. The system according to claim 21, wherein said value is the sum of said detected currents.

23. The system according to claim 20, wherein said sun tracking system directs said at least one moving mechanism to move said at least one light concentrating unit, by comparing selected ones of said detected currents with selected other ones of said detected currents.

24. The system according to claim 15, further comprising at least one flat reflective plate, located at an slanted angle relative to the surface of said at least one cell array, wherein said at least one flat reflective plate directs a portion of said concentrated light falling exterior to said surface, back toward said surface.

25. The system according to claim 1, further comprising a wavelength separator, wherein said wavelength separator receives a multiwavelength light, and wherein said wavelength separator separates said multiwavelength light to a plurality of light beams at different wavelengths, and wherein said wavelength separator directs each of said light beams toward a different one of said at least one light concentrating unit.

26. The system according to claim 25, wherein said wavelength separator is selected from the group consisting of:

prism;

splitter; and

filter.

27. The system according to claim 1 wherein a selected one of said at least one cell array is located on top of a tower, and wherein a plurality of light concentrating units located on the ground, direct said concentrated light at said selected cell array.

28. Method for coupling together a plurality of cells in a cell array, the method comprising the procedures of:

defining, for said plurality of cells, a plurality of array architectures each having at least one parallel connected group for coupling in parallel within said cell array, each said parallel connected group including at least two series connected groups for coupling in series within said parallel connected group, each said series connected group including at least one of said cells for coupling in parallel within said series connected group;

defining a series group flux value for each series connected group as the sum of flux values of light incident on the at least one cell of each said series connected group; and

selecting one of the plurality of array architectures that has a minimal difference between said series group flux values of said at least two series connected groups of each of said at least one parallel connected group.

29. The method according to claim 28, further comprising a preliminary procedure of determining said flux values of light incident on each of said plurality of cells.

30. The method according to claim 28, further comprising a preliminary procedure of detecting said flux values of light incident on each of said plurality of cells.

31. The method according to claim 28, further comprising a procedure of coupling together said cells according to said selected array architecture.

32. The method according to claim 29, wherein said cell flux values are determined according to the distribution of light on said cell array.

33. The method according to claim 30, wherein said cell flux values are detected by a device selected from the group list consisting of:

ammeter; and

flux meter.

34. The method according to claim 33, wherein said procedure of detecting comprises the procedures of:

coupling said ammeter to a selected one of said cells;

detecting a cell flux value of said selected cell;

discoupling said ammeter from said selected cell; and

repeating said procedure of coupling said ammeter, for other ones of said cells.

35. The method according to claim 31, wherein said procedure of coupling is performed when the distribution of light reaching said cells changes.

36. Method for coupling together a plurality of cells in a cell array, the method comprising the procedures of:

determining the sum of a plurality of cell flux values of said cells, in each of a plurality of groups, of each one of a plurality of array architectures;

determining one of said groups in each one of said array architectures, said group having a lowest sum of said cell flux values;

determining the difference between said lowest sum and said sums in other ones of said groups, of each one of said array architectures; and

selecting an array architecture such that said differences are minimal.

37. The method according to claim 36, further comprising a preliminary procedure of determining said array architectures for said cell flux values, wherein each of said array architectures includes said groups, and wherein each of said groups includes selected ones of said cell flux values of each of said cells.

38. The method according to claim 37, further comprising a preliminary procedure of determining said cell flux values.

39. The method according to claim 37, further comprising a preliminary procedure of detecting said cell flux values.

40. The method according to claim 36, further comprising a procedure of coupling together said cells according to said selected array architecture.

41. The method according to claim 40, wherein selected cells in each of said groups are coupled together in parallel.

42. The method according to claim 40, wherein said procedure of coupling is performed when the distribution of light reaching said cells changes.

43. Energy converting system comprising:

means for converting light to electricity, said means for converting light to electricity comprising at least one parallel connected group coupled in parallel within said means for converting light to electricity; and

means for unevenly directing concentrated light onto said means for converting light to electricity,

each said parallel connected group including at least two series connected groups coupled in series within said parallel connected group,

each said series connected group including at least one photovoltaic means coupled in parallel within said series connected group, each said series connected group having a series group flux value associated therewith, said series group flux value being the sum of flux values incident on the at least one photovoltaic means included in said series connected group,

wherein for each of said at least one parallel connected group, said respective at least two series connected groups are selected such that the differences between said selected series connected group series group flux values are minimal.