U.S. patent application number 12/540685 was filed with the patent office on 2009-12-10 for method of manufacturing flexible, lightweight photovoltaic array.
This patent application is currently assigned to ORBITAL SCIENCES CORPORATION. Invention is credited to Robert Minelli.
Application Number | 20090301544 12/540685 |
Document ID | / |
Family ID | 41399178 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090301544 |
Kind Code |
A1 |
Minelli; Robert |
December 10, 2009 |
METHOD OF MANUFACTURING FLEXIBLE, LIGHTWEIGHT PHOTOVOLTAIC
ARRAY
Abstract
A flexible, lightweight photovoltaic cell array includes one or
more individual photovoltaic cell strings attached to a polyimide
film substrate and covered with a polyvinyl fluoride film. Each
photovoltaic cell string includes one or more photovoltaic cells
attached to a flexible printed circuit board. The photovoltaic cell
array may be manufactured by a method that includes bonding at
least one photovoltaic cell to a flexible printed circuit board,
mounting the flexible printed circuit board on a polyimide film
substrate, and covering the flexible printed circuit board with a
substantially transparent polyvinyl fluoride film.
Inventors: |
Minelli; Robert; (Burke,
VA) |
Correspondence
Address: |
ROPES & GRAY LLP
PATENT DOCKETING 39/41, ONE INTERNATIONAL PLACE
BOSTON
MA
02110-2624
US
|
Assignee: |
ORBITAL SCIENCES
CORPORATION
Dulles
VA
|
Family ID: |
41399178 |
Appl. No.: |
12/540685 |
Filed: |
August 13, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12471094 |
May 22, 2009 |
|
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12540685 |
|
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61128510 |
May 22, 2008 |
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61130148 |
May 27, 2008 |
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Current U.S.
Class: |
136/244 ;
257/E31.119; 438/64 |
Current CPC
Class: |
H01L 31/02008 20130101;
H05K 3/305 20130101; H01L 31/0504 20130101; Y02P 70/50 20151101;
H01L 31/048 20130101; H01L 31/188 20130101; H05K 3/281 20130101;
Y02E 10/50 20130101; H05K 2201/10121 20130101; Y02P 70/613
20151101; H05K 2201/0154 20130101; H05K 1/189 20130101; H05K 3/0058
20130101; H05K 2201/015 20130101 |
Class at
Publication: |
136/244 ; 438/64;
257/E31.119 |
International
Class: |
H01L 31/042 20060101
H01L031/042; H01L 31/0216 20060101 H01L031/0216 |
Claims
1. A method of manufacturing a flexible photovoltaic array, the
method comprising: bonding at least one photovoltaic cell to a
flexible printed circuit board; mounting said flexible printed
circuit board on a first side of a polyimide film substrate; and
covering said flexible printed circuit board with a substantially
transparent film.
2. The method of claim 1, further comprising: coating said first
side of said polyimide film substrate with an adhesive; and coating
a second side of said polyimide film substrate with a
high-emissivity coating.
3. The method of claim 2, wherein coating the second side of said
polyimide film substrate with the high-emissivity coating comprises
coating the second side of said polyimide film substrate with
high-emissivity paint.
4. The method of claim 1, further comprising: attaching a bladder
sleeve to said polyimide film substrate prior to covering said
flexible printed circuit board with said film.
5. The method of claim 4 wherein said attaching is performed prior
to covering said flexible printed circuit board with said film.
6. The method of claim 1, wherein mounting said flexible printed
circuit board comprises mounting said flexible printed circuit
board on said polyimide film substrate reinforced with aramid
fibers.
7. The method of claim 1, wherein covering said flexible printed
circuit board comprises covering said flexible printed circuit
board with a substantially transparent polyvinyl fluoride film.
8. The method of claim 1, further comprising: mounting said film
substrate directly to a surface of a spacecraft or an airplane.
9. A flexible photovoltaic array comprising: at least one
photovoltaic cell bonded to a flexible printed circuit board; a
polyimide film substrate on which said flexible printed circuit
board is mounted; and a substantially transparent film covering
said flexible printed circuit board.
10. The flexible photovoltaic array of claim 9, wherein: a first
side of said polyimide film substrate is coated with an adhesive;
and a second side of said polyimide film substrate is coated with a
high-emissivity coating.
11. The flexible photovoltaic array of claim 10, wherein said
flexible printed circuit board is mounted on said first side of
said polyimide film substrate.
12. The flexible photovoltaic array of claim 10, wherein said
high-emissivity coating is high-emissivity paint.
13. The flexible photovoltaic array of claim 9, further comprising:
a bladder sleeve attached thereto.
14. The flexible photovoltaic array of claim 13 wherein said
bladder sleeve is attached to said polyimide film substrate and is
covered by said substantially transparent film.
15. The flexible photovoltaic array of claim 9, wherein said
polyimide film substrate is reinforced with aramid fibers.
16. The flexible photovoltaic array of claim 9, wherein said
substantially transparent film is a polyvinyl fluoride film.
17. The flexible photovoltaic array of claim 9, wherein said
polyimide film substrate is mounted directly to a surface of a
spacecraft or an airplane.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part of U.S. application Ser. No.
12/471,094 filed May 22, 2009, which claims the benefit of U.S.
Provisional Application No. 61/128,510 filed May 22, 2008, and U.S.
Provisional Application No. 61/130,148 filed May 27, 2008, the
entirety of each of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to photovoltaic arrays. More
particularly, the invention relates to flexible, lightweight
photovoltaic arrays suitable for mounting directly on a surface of,
or being deployed from, a spacecraft or an airplane.
[0003] Photovoltaic cell strings include individual photovoltaic
cells connected in series so as to obtain a desired voltage,
according to characteristics of the photovoltaic cells. The
photovoltaic cell strings are then connected in parallel so as to
obtain a desired output capacity or current, thus creating a
photovoltaic cell array.
[0004] Traditionally, photovoltaic arrays have been fabricated on a
graphite panel. Typically, this panel is the thickest member of an
array of photovoltaic cells and contributes most of the weight to
the array. In spacecraft or certain consumer applications, it is
desirable to minimize the weight of the photovoltaic array.
[0005] Additionally, traditional photovoltaic array manufacturing
methods involve extensive manual labor, which gives rise to
relatively high manufacturing costs.
SUMMARY OF THE INVENTION
[0006] The invention relates to a method of manufacturing a
low-cost, flexible, lightweight photovoltaic array.
[0007] According to one aspect, the invention relates to a
photovoltaic array that includes at least one photovoltaic cell
bonded to a flexible printed circuit board. The flexible printed
circuit board is mounted on a substrate of a polyimide film, such
as that sold by E.I. du Pont de Nemours and Company under the
trademark KAPTON.RTM., reinforced with aramid fiber such as that
sold by E.I. du Pont de Nemours and Company under the trademark
KEVLAR.RTM.. The flexible printed circuit board may then be covered
by a substantially transparent abrasion-resistant film (e.g., a
polyvinyl fluoride film, such as that sold by E.I. du Pont de
Nemours and Company under the trademark TEDLAR.RTM.). In one
embodiment, the photovoltaic array is suitable for mounting
directly on a surface of, or being deployed from, a spacecraft or
an airplane.
[0008] In one embodiment, a bladder sleeve is attached to the
polyimide film substrate to facilitate inflatable deployment. The
bladder sleeve preferably is applied prior to covering the
polyimide film substrate with the abrasion-resistant transparent
film. Additionally, the bladder sleeve may also be used for
mechanical boom deployment.
[0009] In one embodiment, a substantial reduction in manufacturing
costs is achieved by bonding the one or more photovoltaic cells to
the printed circuit board using automated assembly equipment such
as for example, surface-mount technology placement systems (e.g.,
pick-and-place machines).
[0010] In one embodiment, one side of the polyimide film substrate,
to which the photovoltaic cells are to be applied is coated with an
adhesive, while the other side of the polyimide film substrate is
coated with a high-emissivity coating (e.g., high-emissivity paint)
to facilitate dissipation of waste heat. The adhesive preferably is
a silicone-based adhesive, such as CV10-2568, available from NuSil
Technology, of Carpinteria, Calif.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The above and other features of the present invention, its
nature and various advantages will be more apparent upon
consideration of the following detailed description, taken in
conjunction with the accompanying drawings, in which like reference
characters represent like parts throughout and in which:
[0012] FIG. 1 is a diagram illustrating the process of assembling a
string carrier, according to an illustrative embodiment of the
invention;
[0013] FIG. 2 is a diagram illustrating the process of assembling a
flexible lightweight photovoltaic array, according to an
illustrative embodiment of the invention;
[0014] FIG. 3 is a schematic diagram of the flexible lightweight
photovoltaic array manufactured according to the process of FIG. 2;
and
[0015] FIG. 4 is a flow chart of a method of manufacturing the
flexible lightweight photovoltaic array of FIG. 3, according to an
illustrative embodiment of the invention.
DETAILED DESCRIPTION
[0016] To provide an overall understanding of the invention,
certain illustrative embodiments will now be described, including a
flexible lightweight photovoltaic array and a method for
manufacturing the photovoltaic array. However, it will be
understood by one of ordinary skill in the art that the systems and
methods described herein may be adapted and modified as is
appropriate for the application being addressed and that the
systems and methods described herein may be employed in other
suitable applications, and that such other additions and
modifications will not depart from the scope hereof.
[0017] Individual photovoltaic cells are connected in series so as
to obtain a desired voltage, according to characteristics of the
photovoltaic cells, to create photovoltaic cell strings. The
photovoltaic cell strings are then connected in parallel so as to
obtain a desired output capacity, thus creating a photovoltaic cell
array. FIG. 1 shows the assembly of individual photovoltaic cell
strings 104 in accordance with an illustrative embodiment of the
present invention. As shown in FIG. 1, one or more photovoltaic
cells 100 are bonded onto a printed circuit board (PCB) 102 to
create a photovoltaic cell string 104. PCB 102 is preferably a
flexible PCB, but alternatively may be a rigid PCB. Photovoltaic
cells 100 preferably are bonded to PCB 102 using automated assembly
equipment such as, for example, surface-mount technology placement
systems. In one embodiment, photovoltaic cells 100 may be soldered
to PCB 102 using pick-and-place machines.
[0018] Photovoltaic cells 100 may soldered to PCB 102 using, for
example, wave soldering. A solder mask is applied to areas of the
photovoltaic cells 100 and the PCB 102 on which solder is not
desired. Photovoltaic cells 100 are then glued to PCB 102 using
pick-and-place machines, and PCB 102 is then run through a wave of
molten solder. The solder wets metal surfaces not coated with the
solder mask to form electrical connections between the photovoltaic
cells 100 and the PCB 102. The use of automated assembly equipment
reduces labor costs and improves the rate at which photovoltaic
cell strings are assembled.
[0019] The photovoltaic cells 100, within a photovoltaic cell
string 104 are wired in series to generate a fixed voltage for each
photovoltaic cell string 104. The number of photovoltaic cells 100
in a particular photovoltaic cell string 104 is determined by the
voltage requirement of the specific application. Preferably, the
return trace is routed on the mounting surface of the PCB 102. In
at least one embodiment, PCB 102 is a multi-layer PCB, and the
return trace is routed underneath the photovoltaic cell string to
reduce the magnetic moment and the associated loop area. A
multi-layer PCB also allows for proper separation, thus reducing
breakdown potential between layers which would result in string
loss.
[0020] In at least one embodiment, string blocking diodes (not
shown) are also installed onto PCB 102 using automated assembly
equipment. Blocking diodes are used to prevent current from flowing
back into one or more photovoltaic cell strings 104 which are not
exposed to sunlight (e.g., in shaded areas or at nighttime).
Additionally, blocking diodes may be installed between photovoltaic
array 200 and the battery (not shown). Once a photovoltaic cell
string 104 is assembled, individual photovoltaic cell strings 104
are wired together in parallel to generate the necessary capacity,
thus creating a photovoltaic array 200.
[0021] FIG. 2 shows the assembly of a photovoltaic array 200 in
accordance with an illustrative embodiment of the present
invention. As shown in FIG. 2, one or more individual photovoltaic
cell strings 104 are mounted onto a polyimide film substrate 106.
The polyimide film substrate 106 preferably is reinforced with
aramid fiber. In addition to photovoltaic cell strings 104, a
bladder sleeve 110 may also be mounted onto polyimide film
substrate 106 to facilitate inflatable deployment in spacecraft or
other applications. Photovoltaic cell strings 104 and bladder
sleeve 110 are mounted onto polyimide film substrate 106 using, for
example, a silicone-based adhesive. In at least one embodiment, the
adhesive is applied to the front face of polyimide film substrate
106 where photovoltaic cell strings 104 and bladder sleeve 110 are
mounted. The back side of polyimide film substrate may be coated
with a high-emissivity coating (e.g., high-emissivity paint) to
facilitate dissipation of waste heat. In at least one embodiment,
one or more wire harnesses (not shown) are also mounted on the
front face of polyimide film substrate 106.
[0022] Once the appropriate number of photovoltaic cell strings 104
are mounted to polyimide film substrate 106, the entire assembly
including photovoltaic cell strings 104, film substrate 106 and
bladder sleeve 110, may be covered with a substantially transparent
film 108. Film 108 may be, for example, a polyvinyl fluoride film
to provide abrasion resistance for photovoltaic cells 102 (FIG.
1).
[0023] FIG. 3 is a schematic diagram of photovoltaic array 200 in
accordance with an illustrative embodiment of the present
invention. Photovoltaic array 200 includes photovoltaic cells 100
bonded onto PCB 102. PCB 102 is mounted onto film substrate 106,
and photovoltaic cells 100 are then covered with film 108.
Photovoltaic array 200 is suitable for mounting directly on a
surface of, or being deployed from, a spacecraft or an
airplane.
[0024] FIG. 4 is a flow chart of a method 300 of manufacturing the
flexible lightweight photovoltaic array 200 of FIG. 3, in
accordance with an illustrative embodiment of the present
invention. In step 302, one or more photovoltaic cells are bonded
to a flexible printed circuit board (PCB) using, for example,
automated assembly equipment. The photovoltaic cells may be
soldered onto the flexible PCB using a pick-and-place machine. In
some embodiments, in addition to photovoltaic cells, blocking
diodes also may be soldered onto the PCB using a pick-and-place
machine.
[0025] Photovoltaic cells (and blocking diodes) are soldered to the
PCB using, for example, wave soldering. A solder mask is applied to
areas of the photovoltaic cells 100 and the PCB 102 on which solder
is not desired. Photovoltaic cells 100 (and blocking diodes) are
then glued to PCB 102 using pick-and-place machines, and PCB 102 is
then run through a wave of molten solder. The solder wets metal
surfaces not coated with the solder mask to form electrical
connections between the photovoltaic cells 100 and the PCB 102.
[0026] The flexible PCB including photovoltaic cells (and blocking
diodes) may then be mounted on a polyimide film substrate (step
304). The polyimide film substrate may be, for example, a 1 mil
sheet of polyimide film reinforced with aramid fibers.
[0027] The flexible PCB preferably is attached to the polyimide
film substrate preferably using a silicone-based adhesive. In at
least one embodiment, one or more wire harnesses and/or one or more
inflatable bladder sleeves are also mounted on the polyimide film
substrate using a silicone-based adhesive. The adhesive is applied
to the front face of the polyimide film substrate, on which the
flexible PCB, one or more wire harnesses, and/or one or more
bladder sleeves are mounted. The back side of the polyimide film
substrate may be coated with a high-emissivity coating (e.g.,
high-emissivity paint) to facilitate dissipation of waste heat. In
step 306, the entire assembly including photovoltaic cells bonded
to the flexible PCB, which is attached to the film substrate is
encapsulated by a substantially transparent film. The substantially
transparent film may be, for example, a polyvinyl fluoride film.
The assembled photovoltaic array is suitable for mounting directly
on a surface of, or being deployed from, a spacecraft or an
airplane.
[0028] The invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The foregoing embodiments are therefore to be considered
in all respects illustrative, rather than limiting of the
invention. The present invention is limited only by the claims
which follow.
* * * * *