U.S. patent application number 10/475574 was filed with the patent office on 2006-04-13 for potted domed solar panel capsule and traffic warning lamps incorporating same.
Invention is credited to Michael Costa, David Robin Green, Nicu Icriverzi, Johny Mendez, Christopher Paynter, Stanislav Polyakov.
Application Number | 20060076047 10/475574 |
Document ID | / |
Family ID | 23096346 |
Filed Date | 2006-04-13 |
United States Patent
Application |
20060076047 |
Kind Code |
A1 |
Green; David Robin ; et
al. |
April 13, 2006 |
Potted domed solar panel capsule and traffic warning lamps
incorporating same
Abstract
A rugged, long lasting, transparent housing of a domed shape
protects an embedded solar panel. More particularly, the solar
panel is embedded in a polymer in a utilized, potted construction.
The use of polyurethane as the polymer produces a durable product
which is transparent and resistant to both thermal and mechanical
stresses. The domed top over the solar panel improves the solar
panel's ability to capture light and thus to operate in locations
where the incidence of light is at a low angle as is found in
northern latitudes.
Inventors: |
Green; David Robin;
(Victoria, CA) ; Paynter; Christopher; (Victoria,
CA) ; Costa; Michael; (Sidney, CA) ; Mendez;
Johny; (Victoria, CA) ; Icriverzi; Nicu;
(Victoria, CA) ; Polyakov; Stanislav; (Victoria,
CA) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
PO BOX 7068
PASADENA
CA
91109-7068
US
|
Family ID: |
23096346 |
Appl. No.: |
10/475574 |
Filed: |
April 22, 2002 |
PCT Filed: |
April 22, 2002 |
PCT NO: |
PCT/CA02/00574 |
371 Date: |
August 9, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60285941 |
Apr 23, 2001 |
|
|
|
Current U.S.
Class: |
136/243 ;
156/285; 156/297; 204/196.27 |
Current CPC
Class: |
E01F 9/608 20160201;
H02S 20/20 20141201; Y02E 70/30 20130101; Y02E 10/52 20130101; H01L
31/0547 20141201; H02S 40/38 20141201; B29C 39/10 20130101; H01L
31/048 20130101; H01L 31/0543 20141201; Y10T 156/1089 20150115;
E01F 9/617 20160201; H01L 31/18 20130101 |
Class at
Publication: |
136/243 ;
156/285; 156/297; 204/196.27 |
International
Class: |
B29C 65/00 20060101
B29C065/00; B32B 37/00 20060101 B32B037/00; C23F 13/00 20060101
C23F013/00 |
Claims
1. A method for encapsulating a solar panel in a fixed mass of
transparent protective material comprising the following steps: (a)
formation of a solar panel by: (i) covering an assembly of wafers
of photovoltaic material, a non-conducting backing sheet, adhesive
bonding the wafers to the backing sheet, electrically conductive
connections between the wafers and terminal electric conductors
attached to the wafers, with a thin layer of liquid polymer
material; (ii) curing the liquid polymer material to hardness; (b)
encapsulating the solar panel formed in step (a) in an additional
mass of transparent protective material by embedding the solar
panel formed in step (a) in additional liquid polymer material held
in a mold; (c) embedding the rim of a component housing in the
additional liquid polymer; and (d) curing the additional liquid
polymer material until it solidifies.
2. The method claimed in claim 1 wherein the curing for the
formation of the solar panel is conducted in a vacuum at a
temperature of approximately 50 degrees Celsius.
3. The method claimed in claim 1 wherein the material selection for
the polymer material of steps (a) and (b) is the same.
4. The method claimed in claim 1 wherein the polymer material used
is a two-component reactive polyurethane.
5. The method claimed in claim 1 wherein the mold has a smooth
concave shape.
6. The method claimed in claim 1 wherein the component housing
contains: (a) rechargeable batteries; (b) one or more lamps; (c)
electronic circuitry to control the operation of the lamps and the
charging of the rechargeable batteries; and (d) electrical
connectors connecting the solar panel to the rechargeable
batteries, the lamps and the electronic circuitry.
7. The method claimed in claim 1 wherein strengthening material,
the presence of which increases the strength or rigidity of the
solar panel or the component housing to which the solar panel is
attached, is embedded in the additional liquid polymer material of
step (b) prior to the curing conducted in step (b).
8. The method claimed in claim 7 wherein the strengthening material
is wire, rods, a lattice or a mesh.
9. The method claimed in claim 7 wherein the strengthening material
is made of metal.
10. A solar generator, comprising: (a) wafers of photovoltaic
material; (b) a non-conducting backing sheet; (c) adhesive bonding
the wafers of photovoltaic material to the backing sheet; (d)
electrically conductive connections between the wafers of
photovoltaic material; (e) terminal electric conductors attached to
the wafers of photovoltaic material; and (f) a solid mass of
transparent protective material having a generally dome-shaped
convex surface and in which the wafers of photovoltaic material,
the non-conducting backing sheet, the adhesive, the electrically
conductive connections and the terminal electrical conductors are
embedded.
11. The solar generator claimed in claim 10 wherein the dome-shaped
surface of the mass of transparent protective material is without a
peripheral rim.
12. The solar generator claimed in claim 10 wherein the mass of
transparent protective material is a two-component reactive
polyurethane.
13. The solar generator claimed in claim 10 wherein the solid mass
of transparent protective material having a dome-shaped surface has
further embedded in it the rim of a component housing.
14. The solar generator claimed in claim 13 wherein the component
housing contains: (a) rechargeable batteries; (b) one or more
lamps; (c) electronic circuitry to control the operation of the
lamps and the charging of the rechargeable batteries; and (d)
electrical connectors connecting the solar panel to the
rechargeable batteries, the lamps and the electronic circuitry.
15. The solar generator claimed in claim 10 wherein the solid mass
of transparent protective material having a dome-shaped surface has
further embedded in it strengthening material the presence of which
increases the strength or rigidity of the solar generator.
16. The solar generator claimed in claim 15 wherein the
strengthening material is wire, rods, a lattice or mesh.
17. The solar generator claimed in claim 16 wherein the
strengthening material is made of metal.
18. The solar generator claimed in claim 10 mounted in the surface
of a supporting structure wherein the dome-shaped surface of the
mass of transparent protective material is selected to have a
curvature that matches smoothly that of the surface in which the
solar generator is mounted.
19. The solar generator claimed in claim 18 wherein the supporting
structure is a traffic control bollard.
20. A traffic warning lamp assembly of the type including a
photovoltaic solar panel array within a protective housing having a
transparent light-receiving protective outer layer for directing
light onto the solar panel array, an electrical energy storage
device such as a cell or battery electrically connected to the
solar panel array for storing electrical energy obtained therefrom,
at least one lamp electrically connected to and powered by the
storage device, and a switch for interrupting and reconnecting the
electric current between the lamp and the storage device;
comprising (a) programmable means such as a microcontroller for
selectably operating the switch at selectable times or intervals to
interrupt or reconnect the lamp from or to the storage device; and
(b) a data coupling device for connecting one or more inputs of the
programmable means to an external source of programming commands
and/or input data, said data coupling device optionally including
or associated with interface software for facilitating entry of
data or commands from the external source to the programmable
means.
21. An assembly as defined in claim 20, in combination with a
portable source of data and/or programming commands that couples
with the data coupling device thereby to permit data and/or
programming commands to be transmitted from the portable source to
the programmable means.
22. An assembly as defined in claim 20, wherein the data coupling
device comprises a wireless receiver.
23. An assembly as defined in claim 21, wherein the source is
selected from hand-held programmable and/or communication devices
such as a Palm Pilot.TM., RIM Blackberry.TM., Handspring.TM., a
television remote control unit or the like.
24. An assembly as defined in claim 20, wherein the lamp is an LED
lamp.
25. An assembly as defined in claim 20, including a pair of lamps
mounted to face generally in the same direction which, when
electrically actuated, are powered on and off at a selected wagger
frequency and out of phase with one another.
26. An assembly as defined in claim 25, additionally comprising a
standard for supporting the lamps above the ground, and serving as
a cross-walk indicator.
27. An assembly as defined in claim 25, wherein the lamps, when
powered on, flicker at a frequency selected to save energy while
attracting visual notice.
28. A traffic warning lamp assembly of the type having: (a) an
exterior protective housing; (b) a photovoltaic solar panel array;
(c) a solar panel protective housing mounted in a portion of the
exterior housing facing ambient light during daylight, said solar
panel protective housing enveloping the photovoltaic solar panel
array and having a transparent light receiving protective outer
layer for directing light onto the solar panel array; (d) an
electrical energy storage device such as a cell or battery
electrically connected to the solar panel array for storing
electrical energy obtained therefrom; (e) at least one lamp mounted
in the exterior housing and electrically connected to and powered
by the storage device; and (f) a switch for interrupting and
reconnecting the electric current between the lamp and the storage
device; wherein the contours or profile of the transparent
light-receiving protective outer layer of the solar panel
protective housing generally merge with the contours or profile of
the portion of the exterior housing in the vicinity of the
transparent light-receiving protective outer layer thereby to
afford additional physical protection for the solar panel
protective housing and its contents.
29. An assembly as defined in claim 28, incorporated into or
functioning as a bollard.
30. An assembly as defined in claim 28, wherein the contours or
profile of the transparent light-receiving protective outer layer
of the solar panel protective housing and the contours or profile
of the portion of the exterior housing in the vicinity of the
transparent light-receiving protective outer layer are generally
convexly curved to facilitate run-off of debris, rain and the like,
the convex curvature of the transparent light-receiving protective
outer layer of the solar panel protective housing being selected to
facilitate the capture of ambient daylight by the solar panel
array.
31. A protective housing for a solar panel array comprising an
integrally formed or bonded housing having a generally convex
transparent shock-resistant light-collecting exterior layer
interposed, when mounted, between the solar panel array and a
source of ambient daylight, characterized by a smooth uninterrupted
continuous exterior surface of such exterior layer sealingly
isolating the solar panel array from the atmosphere, and free at
the periphery thereof from marginal changes of material composition
and from abrupt marginal changes of contour.
32. A protective housing for a solar panel array comprising an
integrally formed or bonded housing having a generally convex
transparent shock-resistant light-collecting exterior layer
interposed, when mounted, between the solar panel array and a
source of ambient daylight, characterized in that the protective
housing sealingly isolates the solar panel array from the
atmosphere, and further characterized by uniformity of material
composition throughout the exterior portions of the housing.
33. A housing as defined in claim 32, wherein the solar panel
assembly is potted in the protective housing.
34. A housing as defined in claim 32, wherein the protective
housing is formed of a selected plastics material, said plastics
material being selected for: (a) transparency and refractive
capability, to avoid reflecting ambient light away from the solar
panel array and to direct a relatively high proportion of light
striking the light-collecting exterior layer onto the solar array;
(b) cohesion, sealing capability, ruggedness and shock resistance;
and (c) maintenance of the foregoing qualities over a selected
range of expected ambient temperatures and/or in direct
sunlight.
35. A housing as defined in claim 32, wherein the selected plastics
material is a selected polyurethane.
36. A method for encapsulating, a solar panel in a fixed mass of
transparent protective material comprising the following steps: (a)
formation of a solar panel by: (i) covering an assembly of wafers
of photovoltaic material, a nonconducting backing sheet, adhesive
bonding the wafers to the backing sheet, electrically conductive
connections between the wafers and terminal electric conductors
attached to the wafers, with a thin layer of liquid polymer
material; (ii) curing the liquid polymer material to hardness; (b)
encapsulating the solar panel formed in step (a) in an additional
mass of transparent protective material by embedding the solar
panel formed in step (a) in additional liquid polymer material held
in a mold having a smooth concave shape; (c) embedding the rim of a
component housing in the additional liquid polymer; and (d) curing
the additional liquid polymer material until it solidifies.
37. A method for encapsulating a solar panel in a fixed mass of
transparent protective material comprising the following steps: (a)
formation of a solar panel by: (i) covering an assembly of wafers
of photovoltaic material, a non-conducting backing sheet, adhesive
bonding the wafers to the backing sheet, electrically conductive
connections between the wafers and terminal electric conductors
attached to the wafers, with a thin layer of liquid polymer
material; (ii) curing the liquid polymer material to hardness; (b)
encapsulating the solar panel formed in step (a) in an additional
mass of transparent protective material by embedding the solar
panel formed in step (a) in additional liquid polymer material held
in a mold, the additional liquid polymer material being of
substantially the same composition as in step (a); (c) embedding
the rim of a component housing in the additional liquid polymer;
and (d) curing the additional liquid polymer material until it
solidifies.
Description
FIELD OF THE TECHNOLOGY
[0001] This invention relates generally to durable solar panel
capsules that encapsulate solar panels, that provide protection and
enhance the solar generation of electricity in conditions where
light is incident at low angles to the plane of the solar panel.
More particularly, the solar panel is embedded in a polymer in a
unitized, potted construction. The use of polyurethane as the
polymer produces a durable product that is transparent and
resistant to both thermal and mechanical stresses. The solar panel
capsule is formed with a generally convex or domed top to improve
the panel's ability to capture light, to facilitate run-off of rain
and debris, and to deflect glancing blows.
BACKGROUND
[0002] Solar panels are widely used as a convenient and portable
supply of electricity. The planar photovoltaic devices in such
panels usually comprise a planar array of interconnected delicate
semiconductor wafers. Typical wafers generate approximately
one-half volt each, and may be connected either serially or in
parallel to supply voltages and currents of selected
magnitudes.
[0003] In conjunction with a rechargeable battery, solar panels are
now used as power sources in locations that would otherwise be
difficult to service with electric power. For example, solar panels
are an ideal choice for marine, highway or road construction
warning signs or lamps, as they do not require the installation of
electric power cable and they can be left unattended for long
periods of time.
[0004] In many situations, lights attached to batteries powered by
solar panels are used for hazard warnings. The public at large come
to rely on them and, in the event of failure, the consequences may
be very serious. The solar panel assemblies used in these
situations need to be reliable.
[0005] To maximize the amount of electricity generated, solar
panels are oriented towards the sun; the plane of the wafer array
is preferably generally perpendicular to the angle of incidence of
the light striking the solar panel. However, where solar panels are
left unattended in locations prone to vandalism or they are
installed by unskilled personnel or are mounted on a moving object
such as a boat or a buoy, it may be impractical to keep the panel
pointed at the sun The best that can be done is to have the solar
panel face generally upwards towards the sky or towards the
expected location of the sun or of the best source of ambient
light.
[0006] To be effective in more northerly latitudes or where the sun
is otherwise low in the sky, solar panels must make efficient use
of the modest amounts of light available. A number of known
techniques are used to achieve this:
[0007] (1) Mirrors or lenses are used to capture a relatively large
proportion of the available light and direct it onto the solar
panel.
[0008] (2) Air gaps and sharp changes in refractive index where
materials meet are avoided so that incident light is not reflected
away. This problem can be particularly severe where the solar panel
is in a location where the sun is low in the sky.
[0009] (3) The materials through which the light passes are
selected to be highly transparent, and the path length through
lossy material is kept to a minimum.
[0010] (4) The surface of the solar panel is kept free of dust,
debris and bird faeces.
[0011] (5) Software and electronics are dedicated to the task of
making best use of the energy available.
[0012] The solar panels and the devices they power need to be
durable when they are placed in remote locations or are required to
operate reliably under difficult conditions. Once installed, they
should last without attention for as long as possible--certainly
for several years. For example, such devices can be expected to be
subject to: [0013] mechanical stresses (from vibration, wind or
rough handling); [0014] thermal stresses (from extreme temperatures
or large fluctuations in temperature); [0015] corrosion (at sea or
in industrial applications); [0016] erosion (from wind or water
borne particulates); or [0017] vandalism in some locations.
[0018] The following patents issued in the United States each
address some of the above design challenges:
[0019] (1) U.S. Pat. No. 4,759,735--"Solar cell powered beacon",
Pagnol and others, 1988. [0020] The Pagnol design places the solar
cells near the outside of a caisson which assists in light capture
but leaves the solar panel vulnerable to accidental damage and
abuse from vandals. The geometry provides no assistance in
gathering light in low-light situations and a centrally placed lamp
casts a shadow over a portion of the solar panel.
[0021] (2) U.S. Pat. No. 4,999,060--"Solar cell packaging assembly
for self-contained light", Szekely and others, 1991. [0022] Szekely
describes a packaging assembly suitable for a "light peg" with a
flat solar panel and an air gap between the cover and the solar
cells. The flatness of the panel make this device unsuitable for
use in locations where there is not plenty of illumination from
above. The interface between the air gap and the exterior cover
forms a surface at which there is a sharp change in refractive
index. At low angles of incidence this causes much of the light to
be reflected away.
[0023] (3) U.S. Pat. No. 5,680,033 "Solar powered warning device",
Cha, 1997. [0024] This warning device makes use of a dome-shaped
upper surface and a focusing effect to capture extra light.
However, it has a hollow casing with an air cavity that may cause
reflection of light arriving at low angles of incidence. The case
is not of a unitized construction and can thus be expected to be
less durable and more prone to failure from mechanical stress
[0025] (4) U.S. Pat. No. 4,626,852 "Buoy lantern system", Dodge,
1986. [0026] This lantern has several moving parts and seals. Over
time these are bound to deteriorate, allowing seawater to enter and
the light to fail. An air gap between the domed cover and the solar
cells will cause reflection of incident light at low angles of
incidence.
[0027] A number of issued patents include descriptions of methods
or selections of materials for embedding the fragile solar cell
wafers in an encapsulant material. For example, U.S. Pat. No.
4,097,308 (Klein et al.), U.S. Pat. No. 4,224,081 (Kawamura et
al.), U.S. Pat. No. 4,380,038 (Anderson et al.), U.S. Pat. No.
4,383,129 (Gupta et al.), U.S. Pat. No. 4,578,526 (Nakano et al.),
U.S. Pat. No. 4,625,070 (Berman et al.), U.S. Pat. No. 4,633,032
(Oido et al.), U.S. Pat. No. 4,869,755 (Huschka et al.), U.S. Pat.
No. 5,008,062 (Anderson et al.), U.S. Pat. No. 5,252,139 (Schmitt
et al.), U.S. Pat. No. 5,252,141 (Inoue et al.), U.S. Pat. No.
5,743,970 (Czubatjy et al.), U.S. Pat. No. 6,114,046 (Hanoka) and
U.S. Pat. No. 6,204,443 B1 (Kiso et al.) all disclose methods for
protecting solar cells by encapsulation or sandwiching in a flat
planar configuration. Such arrangements are of limited utility in
more challenging environments, as flat panels must be securely
mounted to face the sun. Flat panels of this sort are frequently
mounted in frames of the sort shown in U.S. Pat. No. 4,633,032
(Oido et al.). Such frames form a rim which is itself a source of
mechanical failure, leakage and debris build-up. Flat panels of
this sort are more prone to breakage from vandalism
[0028] In U.S. Pat. No. 5,782,552, Green et al. disclose a light
assembly that has its solar panel encapsulated in a potting
material with an exterior protective cover. The solar panel is
disposed at the top and near the surface of the light assembly. In
this position the solar panel suffers from the following problems:
[0029] the delicate solar cells are near the surface of the
assembly and accordingly are subject to damage from shock (vandals)
or from thermal stress; [0030] as the solar panel faces upwards, it
is unable to capture light at low angles of incidence; and [0031]
the exterior protective shell can delaminate from the potting
material, causing a gap that reflects light away.
[0032] In U.S. Pat. No. 6,013,985, Green et al. disclose a
solar-powered light assembly that is permanently sealed using a
potted construction. This provides a rugged construction but does
not disclose any features, such as a domed upper surface, that make
these lamps suitable for low ambient light conditions.
SUMMARY OF THE INVENTION
[0033] The object of the present invention is to provide a rugged,
durable and reliable solar powered generator in a unitized
construction that can be potted with other components to provide a
sealed device that is able to resist mechanical and thermal stress
and which is able to operate in unfavourable conditions of low
ambient light or in northern latitudes. The present invention so
provides by potting (embedding) the solar panel in a polymer in a
unitized structure that may aptly be termed a capsule. The
preferred use of polyurethane as the polymer produces a durable
product that is transparent and resistant to both thermal and
mechanical stresses. The solar panel capsule is formed with a
generally convex or domed top to improve the panel's ability to
capture light, to facilitate run-off of rain and debris, and to
deflect glancing blows.
[0034] The preferred embodiment of the invention is an integrated
assembly having:
[0035] (1) A conventional solar panel disposed as a planar array of
planar wafers mounted on a non-conducting backing, with
electrically conductive connections between the wafers and
electrically conductive terminal connections for delivering
electric power from the entire solar panel when it is illuminated.
[0036] The selection of the solar panel is governed by conventional
factors. A number of suitable solar panel products are available
from manufacturers such as Siemens Corporation or BP Solarex
Inc.
[0037] (2) A capsule for the solar panel made of transparent
polymer material composed of a two-part clear aliphatic urethane
compound available commercially and manifesting the following
desirable characteristics after curing: [0038] (a) a Shore hardness
index of 45-55; [0039] (b) resistance to abrasion and impact down
to -20.degree. F. (for representative temperate zone use); [0040]
(c) over a suitable projected lifetime measured in years, no
significant surface deterioration, increase in hardness, shrinkage
or noticeable color or gloss change after exposure to ultra-violet
light or heat; [0041] (d) no surface corrosion after exposure to
salt spray, detergents, aliphatic hydrocarbons, denatured alcohol
or gasoline; [0042] (e) no discoloration or swelling after exposure
to solutions of 5% potassium hydroxide, 5% sodium chloride, 5%
potassium chloride, 20% sulphuric acid and 20% hydrochloric acid
(these solutions and strengths being considered representative of
the greatest expected chemically corrosive exposures). [0043] (f)
minimal loss of transmitted light by absorption of the
encapsulating material; [0044] (g) a slippery surface to reduce the
adhesion of dirt and dust; [0045] (h) a solid mass both hard enough
to withstand the cutting action of a knife and resilient enough to
absorb the energy of a hammer blow; [0046] (i) low susceptibility
to stresses arising from the expansion of the mass with heat which
may cause buckling of the solar panel or the tearing apart of the
electric connections between the wafers; [0047] (j) strong,
permanent bonding to the solar panel so that no delamination occurs
under conditions of thermal stress caused by high temperatures or
wide fluctuations in temperature.
[0048] The preferred process of manufacturing the solar panel
capsule is as follows: The solar wafer array and associated
electrical connectors are first embedded in a thin layer of the
selected polymer material. This step creates a lightly encapsulated
solar panel that is protected by the polymer envelope during the
remainder of the manufacturing process. The curing of the polymer
material is preferably done in a vacuum with heat to encourage
bubbles of air to expand and rise to the surface. Due to the high
surface tension of the polymer material, some of the bubbles do not
burst of their own accord and as many of them as practically
possible are eliminated, as by pricking with a pin. This procedure
is repeated until the encapsulant material is hardened and
acceptably free of bubbles.
[0049] Next, the solar panel and, optionally, connecting portions
of the traffic warning lamp assembly (conveniently, the connecting
portions may be brackets attached to or integral with a housing for
the battery or other electrical storage device and associated
electrical components, herein referred to as a "component housing")
are immersed in a thick mass of transparent, non-conducting, liquid
polymeric material contained in a suitably shaped mold. The
material used should preferably be the same as that used for the
envelope formed around the solar wafer array. The material is
solidified by a polymerization reaction ("potting") around the
solar panel. The mold is shaped with a concave surface that
produces in the finished capsule a convex and preferably a domed
surface of the mass of polymer material over the solar panel, so
that the domed surface acts as a lens capturing a large amount of
the light available and refracting it onto the solar panel. The
amount of curvature of the domed surface can be varied to suit
different locations.
[0050] A solar panel capsule of the foregoing sort may be
conveniently incorporated into a traffic warning lamp assembly or
the like. In such assembly, the component housing, preferably
shaped approximately as a cylinder, may house batteries, lamp
mountings and connections, and other electronic components (e.g. a
microcontroller for timing the commencement and duration of the ON
cycles of the lamp). The component housing may be joined to the
solar panel by immersing a connecting bracket fixed to a selected
end of the component housing in the liquid polymer material and
then curing the polymer material at room temperature. The component
housing is left open while components such as batteries, control
circuits, microcontrollers and lamps are suitably mounted.
Preferably, the component housing is closed either with a tight
fitting cover held in place by tamper proof screws or by securing a
closing cover to the open end of the component housing using the
polymer material and curing to hardness.
[0051] In a further embodiment, the component housing contains a
microprocessor and communications software so that the operation of
the device may be controlled by a hand-held computer such as a Palm
Pilot.TM..
[0052] In a further embodiment, reinforcement means such as rods,
wire or a lattice of material are embedded in the liquid polymer
material prior to curing to provide stiffening and strengthening of
one or more walls of the component housing or of a cantilevered
flange or the like whereby the component housing is joined to the
solar panel. The choice of material for such reinforcement means is
governed by conventional factors and depends on the geometry of the
finished product and the stresses it is likely to bear.
[0053] In a further embodiment, the solar panel capsule potted
together with the component housing is integrated into a container
such as a bollard. The solar panel capsule is mounted by
conventional means in an aperture made in the upper surface of the
bollard. The contours and profile of the outer layer of the solar
panel capsule generally merge with the contours and profile of the
adjacent portion of the upper surface of the bollard in the
vicinity of the solar panel capsule. The curvature of the domed
surface over the solar panel is carefully controlled to match that
of the bollard as closely as reasonably and economically possible
where they meet so as to further increase resistance to vandals and
to promote run-off of dust, debris and rain.
[0054] A number of advantages may accrue if the construction of the
solar panel capsule is integrated with the construction of the lamp
housing, component housing, or other structure in or on which the
capsule is mounted.
[0055] For example, the translucent lamp cover may in some cases be
advantageously be bonded to the solar panel capsule during the
capsule molding process so that the capsule and lamp cover form
essentially a single integral bonded piece. If the lamp is to shine
in all directions, then the translucent lamp cover may be formed as
a hollow cylinder with a peripheral surface shaped for advantageous
beam dispersion in accordance with conventional lamp cover design,
and the cylinder may be closed at one end by the capsule, forming
an integral extension of the cylindrical lamp cover during the
molding process, one end of the lamp cover being inserted into the
liquid polymer before it is cured to form the capsule. Assuming
that the lamp will be mounted so that the cylindrical axis is
approximately vertical and that the capsule will be positioned at
the top of the integral unit, the peripheral surface of the
cylindrical lamp cover is desirably inset slightly from the
capsule, forming an annular margin on the underside of the capsule.
This annular margin may facilitate mounting of the unit in a
housing, and the overhang of the capsule margin relative to the
inset generally cylindrical surface of the lamp cover may also help
to deflect spray and debris from the lamp cover.
[0056] Further, in many cases it is desirable to integrate the
design of the capsule with the design of the lamp housing or
component housing on or in which the capsule is to be mounted.
[0057] For example, assuming that the capsule will be positioned at
the top of a lamp housing so as to be able to capture a maximum
amount of ambient light, and assuming that the upper surface of the
solar panel capsule has a generally convex or dome shape, it may be
desirable to conform the shape of the upper surface of the solar
panel capsule to the general shape of the top surface of the lamp
housing, or vice versa.
[0058] If, for example, vandalism is a potentially serious problem,
the upper surface of the lamp housing could be generally
cylindrical, or similarly arcuate in two dimensions, and could be
provided with protruding arcuate protective ribs following the
curvature of the housing, the ribs being positioned on either side
of the solar panel capsule. The solar panel capsule in that event
would be desirably formed to have a generally cylindrical or
similarly convex upper surface conforming generally to the upper
cylindrical surface of the lamp housing and extending upwardly to a
lesser extent than the ribs. The ribs should be positioned offset
from the edges of the capsule so as not to interfere with capture
of ambient light and not to interfere with run-off of rain and
debris from the upper surface of the capsule, but should be
sufficiently close to the capsule that they tend to accept the full
force of a blow aimed in the general direction of the upper surface
of the capsule.
[0059] If on the other hand, capsule surface cleanliness is of
major concern, a dome shape or other similar convex surface of
revolution can advantageously be used for the upper surface of the
capsule, thereby promoting run-off in all directions.
[0060] The manner of mounting the solar panel capsule in the
housing also merits careful attention. In many case, the solar
panel capsule will be mounted in a mating aperture in the housing.
Overlap of the margin of the housing aperture by the capsule edges
may be desirable to facilitate run-off of water and debris, in
which case the capsule is desirably formed with a marginal
undersurface forming a shoulder, the downwardly depending capsule
extension fitting more or less snugly into the aperture, and the
entire margin of the aperture is overlain and shielded by the
capsule margin. Note that a peripheral undersurface margin on the
capsule may alternatively be provided by forming the capsule with a
completely flat undersurface and embedding into the capsule when it
is formed connecting flanges or the like for connecting the capsule
to the top of the housing, which flanges may be inset from the
capsule periphery, thereby making available the desired marginal
undersurface of the capsule so that the capsule margin may overlap
the housing aperture. On the other hand, if vandalism is of serious
concern, it may be desirable to have the capsule slightly depressed
relative to the upper surface of the housing so that the upper
surface of the housing takes the brunt of any blow directed
generally at the capsule. Note that depressing the capsule relative
to the upper surface of the housing may have a deleterious effect
on light capture by the solar panel.
[0061] A design trade-off frequently has to be made between serving
the objective of facilitating cleanliness and run-off, the
objective of maximizing ambient light capture, and the objective of
deterring and surviving attacks by vandals. Take for example the
choice of the type and degree of the curvature of the upper surface
of the solar panel capsule. A short radius of curvature tends to
promote run-off and cleanliness. A long radius of curvature tends
to promote light capture and may facilitate integration of the
capsule profile with the profile of the housing in which the
capsule is mounted, especially if the capsule upper surface is not
formed as a surface of revolution but rather is generally
cylindrical, matching a generally cylindrical housing upper
surface. The designer should take into account the applicable
environmental factors in the location in which the solar-powered
lamp is to be installed, and make a balanced judgment about the
design; the design should in many cases be empirically evaluated
over a period of years and modified as required if found to be
inadequate to meet the demands of particular circumstances.
[0062] While various types of lamp are used as examples in this
specification, it is to be understood that the capsule design
according to the invention is suitable for use with many types of
solar-powered devices, including warning sirens or bells,
illuminated information displays, clocks, etc.
SUMMARY OF THE DRAWINGS
[0063] FIG. 1 is a schematic elevation cross-section view of a
polymer-encapsulated solar panel, which may be further encapsulated
in a capsule of the sort illustrated in FIG. 2.
[0064] FIG. 2 is a schematic elevation cross-section view of a mold
holding liquid polymer material in which is embedded a solar panel
(shown inverted relative to its orientation in FIG. 1) and a
portion of a component housing.
[0065] FIG. 3 is a schematic elevation cross-section view of a
solar panel capsule potted with a component housing.
[0066] FIG. 4 is a simplified schematic side elevation view of a
representative solar-powered traffic warning lamp incorporating a
solar panel capsule according to the invention, of the sort formed
pursuant to the technique illustrated by reference to FIG. 2.
[0067] FIG. 5 is a schematic side elevation view, in section, of a
traffic hazard warning lamp with an integrated solar panel capsule
made in accordance with the present invention.
[0068] FIG. 6 is an isometric view of the traffic hazard warning
lamp illustrated in FIG. 5.
[0069] FIG. 7 is an exploded simplified isometric view of a traffic
warning lamp of the sort illustrated in FIG. 6, as mounted in a
traffic bollard.
[0070] FIG. 8 is an isometric view of the traffic warning lamp of
FIG. 6 mounted in a traffic bollard as illustrated in FIG. 7.
[0071] FIG. 9 is an exploded simplified isometric view of a traffic
warning lamp for use as a crosswalk indicator warning device.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0072] FIG. 1 shows a cross-section of a solar panel which is a
component of the preferred embodiment and is generally indicated as
1. Within a polymeric cover 5, planar photovoltaic wafers 2 are
mounted by means of spaced adhesive layer deposits 4 to a
non-conducting planar backing sheet 8. The wafers 2, adhesive
mounts 4, and backing sheet 8 may be selected from among suitable
known conventional such items. Electric connections 3 are made
between the photovoltaic wafers 2 with solder or other suitable
material. Terminal electrical connections are made by attaching
electrical wires 6, 7 to regions of positive and negative charge on
the photovoltaic wafers 2 so as to provide a source of electric
power. These wires 6, 7 may be connected to a storage device (not
shown) such as a battery. When the photovoltaic wafers 2 are
illuminated, they supply power to the storage device.
[0073] To manufacture the solar panel 1, a layer of initially
liquid polymer is poured over the photovoltaic wafers 2, the
adhesive 4, the electric connections 3 and the proximal portions of
the terminal electric connections 6, 7 so as to cover them. The
liquid polymer is cured to hardness at approximately 50.degree. C.
in a vacuum, leaving all of the foregoing items sealed within the
solid polymer cover layer 5, from which connecting wires 6 and 7
protrude for connection to the storage device. Bubbles of air
expand and rise to the surface where they burst either unaided or
with a pin prick.
[0074] FIG. 2 shows a cross-section of the mold and casting
arrangement suitable to produce the preferred embodiment of the
capsule illustrated in FIG. 3. The mold 9 is shaped so as to make a
casting with a smooth domed surface. Molds of different shapes and
depths can be selected to provide different amounts of material
mass and curvature in the finished assembly. The mold 9 is filled
with liquid polymer 10 in which is embedded a solar panel 1 of the
sort depicted in FIG. 1 and the wall extension, connecting bracket
or flange, or other suitable joining element 12 of a component
housing 11. The liquid polymer is cured to hardness slowly,
typically at room temperature for two days, so that the material
mass cures hard and free from striations and defects.
[0075] The resulting solar panel capsule 13, along with embedded
connecting flanges 12 for fixing the capsule 13 to the component
housing 11 is illustrated in section in FIG. 3. The capsule 13
completely surrounds and shields the solar panel 1 of FIG. 1, which
no longer is identifiable as such, since its polymeric cover layer
5 has completely merged into and bonded to the encapsulating
polymeric material of the solar panel capsule 13, which material,
to avoid delamination, should be identical to the material of the
solar panel cover layer 5 of FIG. 1.
[0076] FIG. 4 shows a side elevation view, partially in section of
a traffic hazard warning light 14, which is one particular
embodiment of a complete solar powered lamp assembly constructed in
accordance with the invention. Note that the overall configuration
and layout, apart from the capsule 13 and its contents, is
generally conventional. A solar panel capsule 13 containing a solar
panel 1 and the upper portion of a component housing 11 are
fastened together by the potting technique described above and
illustrated in FIGS. 1, 2 and 3. Flanges 12 (as shown in FIG. 3),
formed as an extension of the component housing 11, ensure that the
component housing 11 is fastened securely with an airtight seal to
the solar panel capsule 13. The resulting traffic hazard warning
light benefits from having a solar panel capsule:
[0077] (1) with a dome shape as this provides a lens effect so that
a large portion of the incident light striking the dome is directed
to the solar panel 1;
[0078] (2) which is formed without a rim to minimize the build up
of debris and dust on the surface;
[0079] (3) with a slippery surface to render it unsuitable as a
perch for wildlife and to minimize the build-up of debris and dust
on the surface;
[0080] (4) of a durable composition resistant to impact and
vibrational stresses;
[0081] (5) which is optically clear; and
[0082] (6) which is resistant to thermal deformation which would
otherwise cause buckling and tearing of the solar panel or
delamination in the region immediately above the solar panel.
[0083] Electrical power generated in the solar panel 1 is conducted
to components, typically first to a storage device and thence to
other possible components within the component housing 11 and to
the lamp (not specifically illustrated). The lamp may be held in
the component housing 11 by means of suitable attachment brackets
or an attachment socket to which are attached conventional
electrical conductors (not shown). A lamp housing 15 with a
conventional reflective interior surface is attached by
conventional means to the component housing 11. One or more light
emitting diodes or other suitable light sources (not shown) are
mounted inside the lamp housing 15 by conventional means and are
connected electrically to power generated from the solar panel 1
through an electric storage device and/or other components mounted
in the component housing 13. A translucent lamp cover 16 is mounted
by conventional means to the lamp housing 15. The hazard warning
light 14 may be suitably mounted by conventional means, an example
of which is shown in FIG. 3 as two protruding bolts 17.
[0084] FIGS. 5 and 6 show an alternative embodiment of a traffic
hazard warning light displaying additional features to those
described above and illustrated in FIGS. 3 and 4. An enhanced
traffic hazard warning light 19 is shown as a cross section of a
side elevation in FIG. 6. The enhanced traffic hazard warning light
19 is as described above for the traffic hazard warning light
numbered 14 in FIG. 4 with the following improvements:
[0085] (1) A solar panel capsule 13 extends over a lamp housing 15
and a lamp cover 16 to provide additional shelter from the elements
and wildlife for the lamp housing 15 and the lamp cover 16.
[0086] (2) The solar panel capsule 13 has bevelled edges to lessen
the chance of chipping at the periphery from rough handling.
[0087] (3) As the solar panel capsule 13 extends beyond the support
provided by the walls of the component housing 11 there is an
increased susceptibility to damage from pressure applied to the
extreme edge of the solar panel capsule 13. To counter this, a
lattice of wires 18, comprised of wire of a suitable gauge,
suitably woven in a rectangular pattern, the number of wires per
unit length and width of which will be dependent in part upon the
gauge of wire chosen, is welded by conventional means to the upper
ends of the component housing walls 12 and immersed in the liquid
polymer 10 (as shown in FIG. 2) prior to curing. Note that this
embedding of the reinforcement lattice 18 in the capsule 13 is
novel and not found in prior traffic warning light designs.
[0088] FIG. 7 shows an exploded view of an illuminated bollard
(FIG. 8) for controlling the flow of traffic, which bollard is a
further particular embodiment of a complete solar powered lamp
assembly constructed in accordance with the invention. The bollard
21 houses and displays a translucent traffic information sign (here
exemplified as a left pointing arrow) 20 which is suitably
illuminated from behind by a selected LED or other suitable source
of light. A traffic hazard lamp of the type illustrated as lamp 19
in FIGS. 5 and 6 and described above is mounted by conventional
means within a lamp housing 23 which is attached by conventional
means to a stand 24 so that the illuminated traffic information
sign 20 is at a suitable height to be visible to motorists. The
traffic hazard lamp 19 illuminates the traffic information sign 20.
The perimeter of the solar panel capsule 13 is fitted closely into
an aperture 22 in the lamp housing 23 so that a watertight seal is
made. Various conventional means are used to seal the perimeter
solar panel capsule 13 into the aperture 22. (FIG. 8 deliberately
exaggerates the gap between the solar panel capsule 13 and the
edges of the lamp housing aperture 22. A practical design goal is
to minimize that gap.)
[0089] The curvature of the upper surfaces of the solar panel
capsule 13 and the lamp housing 23 are selected to balance the
objectives of facilitating cleanliness and run-off, which is
improved with a steeper higher dome shape, against the objectives
of maximizing ambient light capture and deterring and minimizing
the effects of attacks by vandals, which are facilitated by having
a lower profile which more closely matches that of the surrounding
surface. The exact shape is determined by prevailing conditions and
expectations in the location where the bollard is to be installed.
In all cases, the transition area between the solar panel capsule
13 and the lamp housing 23 is smooth to promote run-off and reduce
the build up of debris.
[0090] FIG. 9 shows an exploded view of a crosswalk indicator for
controlling the flow of traffic at a crosswalk which is a further
particular embodiment of a complete solar powered lamp assembly
constructed in accordance with the invention. The crosswalk
indicator is shown generally as 25 and comprises:
[0091] (1) a lamp housing 32 having a flange 33 formed across the
width of the housing at the top and at right angles to the rear
wall of such housing;
[0092] (2) a front cover 30 in which are provided two apertures
31;
[0093] (3) two translucent lamp covers 29, each of which is mounted
into one of the apertures 31 and is securely fastened to make a
watertight seal by conventional means to the lamp housing 30;
[0094] (4) two LED lamps 28, one or more rechargeable storage
batteries 27 and control circuitry 26 all mounted within the lamp
housing, the location of the LED lamps being selected so that the
LED lamps are close to and directly behind the lamp covers 29;
[0095] (5) a solar panel capsule 13 which is potted together with
the flange 33 by encapsulation in liquid polymer and curing to
hardness;
[0096] (6) terminal electrical connections (7 in FIG. 1) from the
solar panel (not shown) which pass through holes in the backing
sheet of the solar panel and into the interior of the lamp housing
where they connect to the rechargeable storage batteries 27;
and
[0097] (7) electrical connections (not shown) between the
rechargeable storage batteries 27, the control circuitry 26 and the
LED lamps 28.
[0098] The front cover 30 mates with and is fastened to the lamp
housing 32 by conventional means and sealed against penetration by
water or air.
[0099] The control circuitry 26 employs a conventionally available
microcontroller such as the Mototrola PIC 16F873, to monitor the
state of the batteries and control at what times of the day the
crosswalk indicator is to be activated. The control circuitry has a
conventionally available infra-red coupling device, such as a Seiko
S8270 AFE, which allows programming instructions or control
parameters to be downloaded from hand held devices such as a
Handspring.TM. or a television remote control unit. This has the
advantage that the crosswalk indicator does not need to be opened
to set a revised illumination schedule thus prolonging the life and
maintaining the quality of the seals employed.
[0100] When activated, the microcontroller operates the LED lamps
as a "wagger" wherein the two LED lamps 28 are alternately
illuminated; when the first lamp is on, the second is off and vice
versa.
[0101] When either of the LED lamps is powered on, the control
circuitry makes the lamp flicker at a frequency designed to both
improve visibility and save electrical energy.
[0102] Much of the detail of the operation of the lamps per se is
either conventional or a matter of straightforward design; see
Applicant's previous U.S. Pat. No. 6,013,985.
[0103] The scope of the invention is not limited to the specific
embodiments illustrated and described herein but is governed by the
appended claims.
* * * * *