solar concentrator device for photovoltaic energy generation
US 20080041441A1
(19) United States (12) Patent Application Publication (10) Pub. No.: US 2008/0041441 A1 Schwartzman (54) SOLAR CONCENTRATOR DEVICE FOR
(43) Pub. Date: (30)
Feb. 21, 2008
Foreign Application Priority Data
PHOTOVOLTAIC ENERGY GENERATION Jun. 29, 2006
(76) Inventor:
gigman Schwartzman, Rehovot
Publication Classi?cation (51)
Int. Cl. H011‘ 31/052
(52)
US. Cl. ..................................................... .. 136/246
Correspondence Address: David Klein
(IL) ........................................ .. 176618
(2006-01)
DEKEL PATENT LTD.
Beit HaRoP im, 18 Menuha VeNahala Street, Room 27 REHOVOT
(21) Appl. No.:
11/759,254
(57) ABSTRACT A solar energy concentrator lens is formed by a prism array. Each prism is designed to de?ect the incident solar rays and fully illuminate a rectangular photovoltaic cell With uniform
intensity. The combination of multiple prisms uniformly illuminating a common target area yields concentrated uni
(22) Filed:
Jun. 7, 2007
form illumination across the target area.
Patent Application Publication
Feb. 21, 2008 Sheet 2 0f 18
US 2008/0041441 A1
FIG. 2
Patent Application Publication
Feb. 21, 2008 Sheet 6 0f 18
US 2008/0041441 A1
FIG. 6
Patent Application Publication
Feb. 21, 2008 Sheet 7 0f 18
US 2008/0041441 A1
FIG. 7
Patent Application Publication
Feb. 21, 2008 Sheet 8 0f 18
US 2008/0041441 A1
FIG. ‘8
Patent Application Publication
Feb. 21, 2008 Sheet 9 0f 18
US 2008/0041441 A1
10
FIG. 9
Patent Application Publication
Feb. 21, 2008 Sheet 10 0f 18
US 2008/0041441 A1
‘ FIG. 10
Patent Application Publication
Feb. 21, 2008 Sheet 12 0f 18
US 2008/0041441 A1
Patent Application Publication
Feb. 21, 2008 Sheet 13 0f 18
FIG. 13
US 2008/0041441 A1
Patent Application Publication
~12.
Feb. 21, 2008 Sheet 14 0f 18
-4
o
US 2008/0041441 A1
4
2
I
2
,1 L
e
O
17 H
F
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J I
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0
8
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FIG. 14
c
Patent Application Publication
Feb. 21, 2008 Sheet 15 0f 18
FIG. 15
US 2008/0041441 A1
Patent Application Publication
Feb. 21, 2008 Sheet 16 0f 18
FIG. 16
US 2008/0041441 A1
Patent Application Publication
Feb. 21, 2008 Sheet 17 0f 18
1
US 2008/0041441 A1
L
FIG. 17
5
Feb. 21, 2008
US 2008/0041441 A1
SOLAR CONCENTRATOR DEVICE FOR PHOTOVOLTAIC ENERGY GENERATION
of the sun projected on the target area is non uniform,
leading to loss of conversion e?iciency. The reason is that loses of Fresnel lens are more signi?cant as the distance
FIELD OF THE INVENTION [0001]
This invention relates to a neW optical concentra
tor, designed for concentrated photovoltaic solar energy
generation. BACKGROUND OF THE INVENTION [0002]
Solar energy conversion modules that convert sun
light to electrical poWer typically employ photovoltaic cells that directly convert sunlight to electrical energy.
from center is larger. These loses Will be even more signi? cant at the comers of the rectangular target.
[0012]
The second problem is that the sharpness of the
boundaries is usually poor; a signi?cant area out of the cell
is illuminated leading to further loss of e?iciency. [0013]
It is a common practice to use a secondary con
centrator/homogeniZer in form of a rectangular re?ector or a light guide mounted near the cell, this solution is far from being ideal in terms of illumination uniformity, adds extra part count and cost.
[0003] Concentrating methods for increasing the light
[0014] Molded sphere pro?led lenses have similar prob
intensity on the cell are usually employed. Such methods include using concentrator lenses and/or re?ectors to focus
lems if cut in rectangular shape to match a rectangular target,
the sun on the cell. See, e.g., US. Pat. No. 6,020,554 Which utiliZes a Fresnel lens in combination With rectangular
re?ectors closely mounted to the photovoltaic cell. [0004] TWo axis sun tracking servomechanism have been developed to keep the lens axis directed to the sun at all
times during the day (e.g., US. Pat. Nos. 4,628,142 and
4,498,456). [0005] The photovoltaic cell is considered to be the most expensive component in a solar energy converter, therefore
increasing the solar illumination intensity by concentrators is considered a very promising cost reduction design
also leading to non uniform illumination and loss of e?i
ciency. SUMMARY OF THE INVENTION
[0015] It is an object of the present invention is to provide an optical concentrator for photovoltaic solar energy gen eration, that more accurately and uniformly concentrate the solar illumination on a rectangular photovoltaic cell. [0016] It is a related object to provide a solar energy generator module that utiliZes such an optical device that concentrates solar energy With su?icient accuracy, on a
approach if loW cost concentrators are utiliZed. It is common
rectangular photovoltaic cell, so that no secondary optical
to design multi module arrays on tWo axis tracking panels, each module is usually designed With a rectangular lens that alloW maximum panel area utiliZation for collecting the solar energy. See, e.g., US. Pat. No. 5,125,983. [0006] The amount of electrical energy generated by the photovoltaic cell is related to the intensity of solar illumi
concentrator or homogeniZer is required. [0017] These objects, as Well as others, that Will become apparent upon reference to the folloWing detailed descrip tion and accompanying draWings, are accomplished by a neW solar energy concentrating device, Which is specially designed for high intensity uniform illumination of a rect angular photovoltaic cell. The device is comprised of a
nation the cell absorbs. Several research groups shoWed that When concentrated solar illumination is implemented With
multiple solar radiation de?ecting elements each de?ecting
specially designed photovoltaic cells, the conversion e?i
element fully illuminating a common target area that con
ciency can increase above What is achievable With non
tains a photovoltaic cell. A multitude of such solar radiation de?ecting elements, illuminating a common target area
concentrated designs, reaching levels of 30% and higher. [0007] Photovoltaic cells for concentrated solar energy conversion are relatively small, thin, rectangular or square
yields high intensity uniform illumination of the cell.
semiconductor dies that is cut from a large semiconductor
prism array. Each prism is designed to de?ect the incident solar rays and fully illuminate a rectangular photovoltaic cell With uniform intensity. The combination of multiple prisms
Wafer after appropriate processing. [0008] See, eg Spectrolab Inc. (a Boeing company) pub lication “photovoltaic products”, describing “Triple Junction Concentrator Solar Cells”. These cells are designed for concentration ratio of X200-X400 suns With e?iciency greater than 30%. Their active area is square and they are available in dimensions of 1x1 or 0.5>
(19) United States (12) Patent Application Publication (10) Pub. No.: US 2008/0041441 A1 Schwartzman (54) SOLAR CONCENTRATOR DEVICE FOR
(43) Pub. Date: (30)
Feb. 21, 2008
Foreign Application Priority Data
PHOTOVOLTAIC ENERGY GENERATION Jun. 29, 2006
(76) Inventor:
gigman Schwartzman, Rehovot
Publication Classi?cation (51)
Int. Cl. H011‘ 31/052
(52)
US. Cl. ..................................................... .. 136/246
Correspondence Address: David Klein
(IL) ........................................ .. 176618
(2006-01)
DEKEL PATENT LTD.
Beit HaRoP im, 18 Menuha VeNahala Street, Room 27 REHOVOT
(21) Appl. No.:
11/759,254
(57) ABSTRACT A solar energy concentrator lens is formed by a prism array. Each prism is designed to de?ect the incident solar rays and fully illuminate a rectangular photovoltaic cell With uniform
intensity. The combination of multiple prisms uniformly illuminating a common target area yields concentrated uni
(22) Filed:
Jun. 7, 2007
form illumination across the target area.
Patent Application Publication
Feb. 21, 2008 Sheet 2 0f 18
US 2008/0041441 A1
FIG. 2
Patent Application Publication
Feb. 21, 2008 Sheet 6 0f 18
US 2008/0041441 A1
FIG. 6
Patent Application Publication
Feb. 21, 2008 Sheet 7 0f 18
US 2008/0041441 A1
FIG. 7
Patent Application Publication
Feb. 21, 2008 Sheet 8 0f 18
US 2008/0041441 A1
FIG. ‘8
Patent Application Publication
Feb. 21, 2008 Sheet 9 0f 18
US 2008/0041441 A1
10
FIG. 9
Patent Application Publication
Feb. 21, 2008 Sheet 10 0f 18
US 2008/0041441 A1
‘ FIG. 10
Patent Application Publication
Feb. 21, 2008 Sheet 12 0f 18
US 2008/0041441 A1
Patent Application Publication
Feb. 21, 2008 Sheet 13 0f 18
FIG. 13
US 2008/0041441 A1
Patent Application Publication
~12.
Feb. 21, 2008 Sheet 14 0f 18
-4
o
US 2008/0041441 A1
4
2
I
2
,1 L
e
O
17 H
F
H
J I
-4 .L
E
0
8
I
*2
K
v
FIG. 14
c
Patent Application Publication
Feb. 21, 2008 Sheet 15 0f 18
FIG. 15
US 2008/0041441 A1
Patent Application Publication
Feb. 21, 2008 Sheet 16 0f 18
FIG. 16
US 2008/0041441 A1
Patent Application Publication
Feb. 21, 2008 Sheet 17 0f 18
1
US 2008/0041441 A1
L
FIG. 17
5
Feb. 21, 2008
US 2008/0041441 A1
SOLAR CONCENTRATOR DEVICE FOR PHOTOVOLTAIC ENERGY GENERATION
of the sun projected on the target area is non uniform,
leading to loss of conversion e?iciency. The reason is that loses of Fresnel lens are more signi?cant as the distance
FIELD OF THE INVENTION [0001]
This invention relates to a neW optical concentra
tor, designed for concentrated photovoltaic solar energy
generation. BACKGROUND OF THE INVENTION [0002]
Solar energy conversion modules that convert sun
light to electrical poWer typically employ photovoltaic cells that directly convert sunlight to electrical energy.
from center is larger. These loses Will be even more signi? cant at the comers of the rectangular target.
[0012]
The second problem is that the sharpness of the
boundaries is usually poor; a signi?cant area out of the cell
is illuminated leading to further loss of e?iciency. [0013]
It is a common practice to use a secondary con
centrator/homogeniZer in form of a rectangular re?ector or a light guide mounted near the cell, this solution is far from being ideal in terms of illumination uniformity, adds extra part count and cost.
[0003] Concentrating methods for increasing the light
[0014] Molded sphere pro?led lenses have similar prob
intensity on the cell are usually employed. Such methods include using concentrator lenses and/or re?ectors to focus
lems if cut in rectangular shape to match a rectangular target,
the sun on the cell. See, e.g., US. Pat. No. 6,020,554 Which utiliZes a Fresnel lens in combination With rectangular
re?ectors closely mounted to the photovoltaic cell. [0004] TWo axis sun tracking servomechanism have been developed to keep the lens axis directed to the sun at all
times during the day (e.g., US. Pat. Nos. 4,628,142 and
4,498,456). [0005] The photovoltaic cell is considered to be the most expensive component in a solar energy converter, therefore
increasing the solar illumination intensity by concentrators is considered a very promising cost reduction design
also leading to non uniform illumination and loss of e?i
ciency. SUMMARY OF THE INVENTION
[0015] It is an object of the present invention is to provide an optical concentrator for photovoltaic solar energy gen eration, that more accurately and uniformly concentrate the solar illumination on a rectangular photovoltaic cell. [0016] It is a related object to provide a solar energy generator module that utiliZes such an optical device that concentrates solar energy With su?icient accuracy, on a
approach if loW cost concentrators are utiliZed. It is common
rectangular photovoltaic cell, so that no secondary optical
to design multi module arrays on tWo axis tracking panels, each module is usually designed With a rectangular lens that alloW maximum panel area utiliZation for collecting the solar energy. See, e.g., US. Pat. No. 5,125,983. [0006] The amount of electrical energy generated by the photovoltaic cell is related to the intensity of solar illumi
concentrator or homogeniZer is required. [0017] These objects, as Well as others, that Will become apparent upon reference to the folloWing detailed descrip tion and accompanying draWings, are accomplished by a neW solar energy concentrating device, Which is specially designed for high intensity uniform illumination of a rect angular photovoltaic cell. The device is comprised of a
nation the cell absorbs. Several research groups shoWed that When concentrated solar illumination is implemented With
multiple solar radiation de?ecting elements each de?ecting
specially designed photovoltaic cells, the conversion e?i
element fully illuminating a common target area that con
ciency can increase above What is achievable With non
tains a photovoltaic cell. A multitude of such solar radiation de?ecting elements, illuminating a common target area
concentrated designs, reaching levels of 30% and higher. [0007] Photovoltaic cells for concentrated solar energy conversion are relatively small, thin, rectangular or square
yields high intensity uniform illumination of the cell.
semiconductor dies that is cut from a large semiconductor
prism array. Each prism is designed to de?ect the incident solar rays and fully illuminate a rectangular photovoltaic cell With uniform intensity. The combination of multiple prisms
Wafer after appropriate processing. [0008] See, eg Spectrolab Inc. (a Boeing company) pub lication “photovoltaic products”, describing “Triple Junction Concentrator Solar Cells”. These cells are designed for concentration ratio of X200-X400 suns With e?iciency greater than 30%. Their active area is square and they are available in dimensions of 1x1 or 0.5>
