Note: Descriptions are shown in the official language in which they were submitted.
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A WINDOW
FIELD OF THE DISCLOSED SUBJECT MATTER
The presently disclosed subject matter relates to solar windows configured to
generate electricity, especially those using optical elements to concentrate
impinging
solar radiation.
BACKGROUND OF THE DISCLOSED SUBJECT MATTER
It is well known that solar radiation can be utilized by various methods to
produce useable energy. One method involves the use of a photovoltaic (PV)
cell, which
is configured to convert solar radiation into electricity. Solar radiation
collectors are
typically used to gather sunlight or other radiation and direct it toward a
photovoltaic
cell. Often, concentrators are provided in order to focus solar radiation
impinging on an
aperture having a certain area onto a PV cell having a smaller area, thus
increasing the
efficiency of the PV cell and reducing the cost thereof.
Often, a plurality of photovoltaic cells is provided to form a single module.
This
module may be formed with characteristics providing other benefits which are
not
necessarily related to energy production. For example, the module may allow
some light
to pass therethrough without being used for energy production. Such a module
may be
installed in a building and used as a window or skylight.
On the other hand, many contemporary office and public buildings make use of
large glass windows and walls. These large area windows provide natural
illumination
inside the building during day time, and provide inhabitants with view
outside, which
may improve the working environment. The windows are usually double glazed
providing the required thermal and acoustic isolation. In an effort to reduce
air
conditioning costs and in order to increase comfort, the windows may be
designed to
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reduce the amount of direct sun radiation entering the building and/or may be
equipped
with curtains or venetian blinds that can be adjusted to block such radiation.
The development of cost effective photo-voltaic systems brought a new
dimension into the design of energy conserving buildings, allowing self-
production of
some of the electricity power consumption. In most buildings the window and
wall
areas are much larger than the roof area, thus being good candidates for the
integration
of solar photo-voltaic systems. However, such integration of the PV systems
should not
adversely affect the original purpose of windows and window walls (curtain
walls).
It will be appreciated that herein references to windows also refers to solar
skylights, and any reference to solar windows/curtain walls/blinds is also
applicable to
skylights.
SUMMARY OF THE DISCLOSED SUBJECT MATTER
According to one aspect of the present invention, there is provided a window
comprising a front pane and a rear pane defining a space therebetween. At
least partially
transparent liquid disposed within said space, the liquid having a refractive
index so
close to that of the front pane that a majority of light impinging the front
pane will pass
therethrough into said liquid. At least one PV cell disposed in said space so
that at least
a first portion of light that passes through the front pane into the liquid is
directed to the
PV cell, optionally by a light-ray separator disposed within said space, for
conversion of
said first portion of light into electrical energy.
The liquid can have a refractive index of between 1.4 and 1.6.
The separator can be configured to direct the first portion to the PV cell by
total
internal reflection. The light-ray separator can be disposed in a first angle
with respect
to the front pane, the first angle is determined in such a way so that the
first portion will
be directed to the PV cell by total internal reflection. The light-ray
separator can further
include an adjusting mechanism for adjusting said first angle. By which the
angle can be
adjusted so as to determine the amount of light-rays to be directed to the PV
cell.
The PV cell can be adjustably disposed in a second angle with respect to the
separator, wherein the second angle can be adjusted so as to determine the
desired
viewing cone through the window.
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The light-ray separator can be configured to direct a second portion of the
light
ray toward the rear pane, the second portion being separate from the first
portion.
The separator can be a beam splitter such as a partial transparent mirror.
Alternatively, the separator can comprise a first transparent plate and a
second
transparent plate disposed adjacent one another and defining a gap
therebetween. The
gap can comprise medium having a refractive index smaller than that of the
first plate
thereby causing total internal reflection. The medium can be gas or air and
the first and
second plates can be sealingly affixed to one another solely along the
perimeter thereof
The separator can be covered by the liquid, or the liquid can fill up the
space.
The window can include a plurality of PV cells arranged an array and disposed
along at least one dimension of the window perpendicular to the thickness
thereof
The light-ray separator can include a plurality of light ray separating units
arranged in a separators array. The PV cell array can includes a plurality of
PV cell
arrays and the separators array can include a plurality of separators arrays,
wherein the
PV cell arrays are disposed one adjacent the other, and wherein each array
being
provided with at least one of the separator arrays for directing said first
portion of light
rays thereto.
The window can be provided with folding means for folding the PV cells
thereby substantially precluding the light-rays from impinging thereon. In
addition, the
separator array can be provided with folding means for folding thereof thereby
allowing
substantially all the light-rays impinging on the front pane to travel toward
the rear
pane.
The window can further comprise an insulation layer for insulating the
interior
of the window form the exterior thereof, the insulation layer is disposed
between rear
pane and front pane. The insulation layer can be defined between a divider
disposed in
the space and the front pane or the rear pane, forming therebetween a cavity.
According to a further aspect of the present invention, there is provided a
kit for
a PV assembly for a double glazed window having a front and rear pane with a
space
therebetween. The kit comprising an array of PV cells configured to convert
light rays
to electrical energy, at least one light-ray separator; and means for mounting
the array
and the at least one light ray separator within the space at such orientation
relative to
each other and to said front pane so that only when the space comprises at
least partially
transparent liquid having a refractive index so close to that of the front
pane that a
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majority of light impinging the front pane will pass therethrough into the
liquid, at least
a first portion of light that passes through the front pane into the liquid is
directed by the
separator to the PV for conversion thereof into electrical energy.
The separator can be configured to direct the first portion to the array by
total
internal reflection.
The means for mounting can be configured to allow disposing the light-ray
separator in a first angle with respect to the front pane, the first angle is
determined in
such a way so that the at least a first portion will be directed to the array
by total internal
reflection. The means for mounting can be provided with an adjusting mechanism
for
adjusting the first angle. And, can be configured to allow disposing the array
in a second
angle with respect to the rear pane, the second angle is determined in
accordance with a
desired direction of a viewing cone through the rear pane. The adjusting
mechanism can
be further configured for adjusting the position of the array with respect to
the rear
pane.
The light-ray separator is configured to direct a second portion of the light
ray
toward the rear pane, the second portion being separate from the first
portion.
The kit can be provided with folding means for folding the PV cell array
thereby
substantially precluding the light-rays from impinging thereon. The folding
means can
be configured for folding the separators, thereby allowing substantially all
the light-
rays to travel through the rear pane.
According to a further aspect of the present invention, there is provided a
window comprising: at least a front pane, at least one PV cell disposed
adjacent the
front pane, a separator mounted adjacent said PV cell for directing toward the
PV cell at
least a first portion of light rays impinging on and passing through the front
pane; and,
at least partially transparent liquid disposed between the separator and the
front pane,
the liquid having a refractive index so close to that of the front pane that a
majority of
light impinging the front pane will pass therethrough into the liquid.
The window can further comprise a rear pane disposed adjacent the separator,
wherein the liquid is further disposed between the separator and said rear
pane.
According to still a further aspect of the present invention, there is
provided a
method for mounting a PV assembly in a double glazed window having a front and
rear
pane with a space therebetween, the method comprising: introducing into the
space at
least partially transparent liquid having a refractive index so close to that
of the front
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pane that a majority of light impinging the front pane will pass therethrough
into the
liquid; and
disposing at least one PV cell in the space so that at least a first portion
of light that
passes through the front pane into the liquid is directed thereto for
conversion thereof
into electrical energy.
The method can further comprise disposing a light-ray separator adjacent the
PV
cell, the light-ray separator being configure for directing at least a first
portion of light
rays impinging on and passing through the front pane.
The method can further comprise determining the angle of the light ray
separator
with respect to the front pane in such a way so that the at least a first
portion will be
directed to the PV cell by total internal reflection. And can yet further
comprise
providing adjusting means for adjusting the angle of the light ray separator
with respect
to the front pane. And can comprise providing adjusting means for adjusting
the angle
of the light ray separator with respect to the front pane.
Herein the specification and claims, the term "concentration" refers to any
level
of concentration, including x 1 concentration (no concentration at all) or
concentration
levels < x 1.
Herein the specification and claims, the term "transparent" is intended to
include a fully transparent material, partially transparent material, or
translucent martial
allowing at least some EM wave length in the visible spectrum to travel
through the
material.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to understand the presently disclosed subject matter and to see how
it
may be carried out in practice, embodiments will now be described, by way of
non-
limiting example only, with reference to the accompanying drawings, in which:
Fig. 1 is a side cross-sectional view of a window according to an example of
the
presently disclosed subject matter;
Fig. 2 are graphs designed to assist in selecting parameters of the window of
in
Fig. 1;
Fig. 3A is a side cross-sectional view of a light-ray separator according to
an
example of the presently disclosed subject matter;
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Fig. 3B is a side cross-sectional view of a light-ray separator according to
another example of the presently disclosed subject matter;
Fig. 3C is a side cross-sectional view of the light-ray separator of Fig. 4B
mounted inside a double glazed window;
Fig. 4A is a side cross-sectional view of the window of Fig. 1 configured for
a
forward viewing cone;
Fig. 4B is a side cross-sectional view of the window of Fig. 1 configured for
a
downward viewing cone;
Fig. 5 is a side cross-sectional view of a window having an insulating cavity
according to an example of the presently disclosed subject matter;
Fig. 6A is a side cross-sectional view of a window having a dynamic PV
assembly according to an example of the presently disclosed subject matter;
Fig. 6B is a side cross-sectional view of the window of Fig. 6A in position
configured for a downward viewing cone; and,
Fig. 6C is a side cross-sectional view of the window of Fig. 6A in the folded
position.
Fig. 6D is a side perspective view of the window of Fig. 6A in the deployed
position.
DETAILED DESCRIPTION OF EMBODIMENTS
As illustrated in Fig. 1, there is provided a photovoltaic (PV) window, which
is
generally indicated at 10. The window 10 comprises a front pane 12
constituting an
exterior surface of the window, a rear pane 14 constituting a second exterior
layer of the
window. Front pane 12 and rear pane 14 defining a space 15 therebetween for
mounting
a PV assembly 16 therein, and for filling thereof with liquid 26.. The front
pane 12 and
the rear pane 14 define an outer surface 12a and 14a facing the outside of the
building
and the inside of the building respectively. In addition, each of the front
pane 12 and the
rear pane 14 define an inner surface 12b and 14b, respectfully, facing the PV
assembly
16. The window 10 may be designed for mounting vertically or horizontally, as
illustrated, or in any other suitable disposition. It will be appreciated by
one skilled in
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the art the necessary design parameters to apply to any given design based on
the
description presented hereinbelow.
The window 10, and specifically the PV assembly 16 thereof, is designed so as
to utilize solar radiation impinging on the front pane 12a at an angle within
an
acceptance angle 0a for generation of electricity, and to allow passage
therethrough of
solar radiation impinging on the front pane 12 at an angle outside the
acceptance angle.
As will be described, the acceptance angle 0a is calculated as a function of
material and
constructional properties of the PV assembly 16.
The rear pane 14 may be configured to diffuse radiation passing therethrough,
thereby providing more uniform illumination using light impinging on the
window 10 at
an angle outside the acceptance angle
The PV assembly 16 comprises at least one PV cell 18, which is designed to
convert impinging solar radiation into electricity. The PV assembly 16 can
further
include a transparent or translucent light-ray separator 22, one side thereof
disposed
adjacent to one side of the PV cell 18 forming an angle therebetween, while
the other
side thereof is disposed adjacent the inner surface 12b of the front pane 12
and forming
an angle a therebetween. The PV cell 18 extends between the inner surfaces 12b
and
14b, in such a way so as to allow at least some of the light impinging on the
front pane
12 and traveling therethrough to incident onto the PV cell, either directly or
after being
reflected by the separator 22.
The liquid 26 inside the space 15 is a transparent liquid which has a
refractive
index similar to a solid material, preferably in the range of 1.4-1.6, such as
water. In
addition preferably the transparent liquid material is characterized by
viscosity which
ranges from less than 1cP (such as water) up to 250,000cP (such as hard
silicone gel)
which can be measured at 25 C according to ASTM D4283. This way the PV cells
which can be immersed in the liquid are protected from damages caused by
window
vibrations, such that often occur in buildings. In addition, according to an
example,
utilizing liquid having viscosity which allows displacing the PV assembly
immersed
therein, allows dynamically adjusting the disposition of the PV assembly
relative to the
front and rear pane. According to one example the optical liquid is silicone
based
optical oil which can endure the high energy irradiation along the required
life time of
the product.
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The light-ray separator 22 is an optical components configured to direct a
first
portion of the light impinging thereon toward the rear pane and to direct a
second
portion of the light impinging thereon toward the PV cells 18. In one example
the light
separator is a partial transparent mirror, such as 80% reflecting 20%
transmitting mirror.
In this case the mirror reflects most of the impinging ray towards the PV cell
18,
however, transmitting part of the light rays through the rear pane 14 into the
room. This
way, a viewer located inside the room can see through the window.
According to an alternative example the light-ray separator comprises a
martial
having a refractive index which is smaller than the one of the liquid 26
thereby causing
the light rays impinging thereon in an angel which is larger than the critical
angle to be
totally reflected and not directed towards the rear pane 14. Examples of such
a separator
are explained in detail hereinafter with regards to Figs 3A through 3C. In
this case, the
angle a between the light-ray separator 22 and inner face 12b of front pane 12
is
determined such that light rays entering the front pane 12 within a decried
acceptance
angle Oa will be reflected via total internal reflection off of the light-ray
separator 22 and
the exterior surface 12a of the front pane 12. For a desired acceptance angle,
which may
be determined based on the location in which the window 10 is to be installed
relative to
the sun, the angle a between the light-ray separator 22 and inner face 12b is
given as:
_1( cos Oa (1
cos Oa
= 0 ¨sin ) = sin-1 JO sin-1
where n is the refractive index of the liquid 26 inside space 15. According to
this
formula, the acceptance angle 0õ, is the range of spatial angles of light-rays
impinging
on the front pane 12, in which theoretically all the light rays will reach the
separator 22
at an angle greater than the critical angle thus will be totally reflected.
This way the
separator can be positioned with respect to the PV cells 18 in such a way so
as to direct
all the reflected light rays thereto. The above formula assumes that the
refractive index
of the liquid 26 is substantially the same as that of the front pane 12. In
practice,
however, the refractive index of the liquid 26 can be so close to that of the
front pane 12
that at least the majority of light impinging the front pane 12 will pass
therethrough into
liquid 26. It is appreciated that small differences between the refractive
indices of the
liquid 26 and the front pane 12 do not change the principle of operation,
although it
might have a slight effect on the value of the acceptance angle (for a given
a).
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As mentioned above, according to the illustrated example, light rays which
impinges on the window 10 within the acceptance angle 0õõ for example along
the path
designated by 32, is reflected by the light-ray separator 22 toward the PV
cell 18. Light
which impinges on the window 10 outside the acceptance angle O., for example
along
the path designated by 34, travels through the separator 22 and exits the
window
through the rear pane 14.
By selecting the appropriate disposition of the separator 22 with respect to
the
the PV cell 18 and the front pane 12, the amount of heat entering a room can
be
controlled. As shown in Fig. 2, which is explained hereinafter in detail, the
acceptance
angle 0õ, may be selected such that all sunlight during the summer, or at
least during the
hottest part of the day, is reflected by the separator 22 toward the PV cell
18, thus
reducing the solar heat load within the room, and all sunlight during the
winter exits via
the rear pane 14, thus increasing the solar heat load within the room. This
arrangement
will reduce the amount of cooling required during the summer, and decrease the
amount
of heating required during the winter, saving energy all year.
It is appreciated that the window 10 can include an array of PV cells 18 each
provided with a light ray separator 22 concentrating at least some of the
light ray onto
the PV cells 18, the array of PV cells can be disposed along the length of the
window
and can include a plurality of arrays disposed along the height of the window
10. The
distance between each array of PV cells can be determined in accordance with
the
amount of light rays which can be reflected from the separator thereto.
According to an alternative Example, the window can be formed with a plurality
of window units, each having a front pane and a back pane, a PV cell mounted
therebetween, and a separator for directing at least one a portion of the
light rays
impinging on the front pane and traveling therethrough toward the PV cell.
Each cell is
filled with a transparent liquid for allowing at least the majority of the
light rays
impinging on the front pane to reach the separator. The window units are
organized in
two dimensional array one next to the other forming together a window.
Reference is now made to Fig. 3A, the light-ray separator 50 includes a first
and
second plates 52a and 52b affixed to one another at the perimeter thereof,
thereby
forming a gap 54 therebetween. The first and second plates 52a and 52b are
made of a
transparent material, such as glass or plastic, etc. The gap 54 can be filled
with material
having a lower refractive index with respect to that of the plates 52a and
52b, such as
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air, thus allowing total internal reflection of light rays striking the
boundary between the
two mediums in an angle which is larger than the critical angle. It is
appreciated that the
above formula assumes that the material having lower refractive index with
respect to
the front pane and the liquid is air. Affixing the first and second plates 52a
and 52b at
the perimeter thereof is carried out by gluing or welding them to one another,
in any
known fashion. It is appreciated that the bond between the first and second
plates 52a
and 52b seals the gap 54 thus precluding liquid from entering therein. In
order to
preclude substantial optical losses due to the material of the glue or the
welding
material, the welding or gluing line is kept to the minimum.
According to one example the first and second plates 52a and 52b are thin
foils
of transparent optical material which can be for example thinner than 1 mm, or
according to another example in the range of 0.2-0.5mm. The foil can be made
out of
glass, plastic material such as PMMA, Poly-Carbonate, or Mylar (BoPET).
Obtaining a
sealed welding line along the perimeter of the two coupled foils can be
obtained by laser
welding, ultrasonic, heat or chemical welding.
According to one example the seperator is formed with a pair of glass based
plates such as Borosilicate glass. In this case the two glass plates can be
welded to one
another using fit based welding or laser welding.
It is further appreciated that in order to allow the separator 50 to form the
triangular space when disposed inside the double glazed window, it is formed
with a
rigid structure. This can be carried out by utilizing rigid plates, such as
glass or plastic.
Alternatively, the separator can include two thin flexible transparent films
affixed to one another at the perimeter thereof, thereby forming together an
inflatable
structure. When the inflatable structure is filled with air or gas under
pressure the
separator becomes rigid, and can be positioned at a desired angle with respect
to the PV
cell and the front pane.
Fig. 3B illustrates a light-ray separator according to another example,
separator
60 includes a first and second plates 62a and 62b, having an air gap 64
therebetween.
According to this example, at least one of the first and second plates 62a and
62b
includes a spacer 66 at the perimeter thereof sealingly affixed to the
perimeter of the
other plate. Due to the spacer 66, the air gap 64 formed between the plates
62a and 62b
is relatively large thereby ensuring the total internal reflection.
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It will be understood that the example of Fig. 3a is best applied when the
plates
are made of glass thus, the air gap therebetween is maintained. However when
the
plates are made out of plastic, for example, due to slight distortion of the
material the air
gap might be maintained and thus total internal reflection might not occur.
As shown in Fig. 3C, the separator 60 is disposed between a front pane 72a and
a rear pane 72b of a window 70, in an angle a and is immersed with liquid 78.
When a light ray 86 impinges the front pane 72a in an angle which is inside
the
acceptance angle , the light ray 86 travels through the liquid 78 and the
first plate 62a
until reaching the boundary between the first plate and the air gap 64. Since
the light ray
86 entered the front pane 72a inside the acceptance angle, it reaches the
boundary in an
angle larger than the critical angle, thus since the refraction index of the
air inside the
air gap 64 is smaller than the refraction index of the plate 62a, - total
internal refraction
occurs. As a result, the light ray 86 is reflected back through the first
plate 62a back into
the liquid 78 until reaching the PV cell 74 where the light is converted to
electric
energy. It is appreciated that some of the light rays reflected by the
separator may not
reach the PV cell 74 directly, rather due to the low angle of incidence, may
be directed
back to the front pane 72a, (here illustrated for example as light ray 86a).
However, due
to the difference between the refractive index of the front pane 72a and that
of the air
outside the window 10, the light ray 86a will be totally reflected back into
the liquid 78,
until eventually reaching the PV cell 74.
On the other hand, when a light ray 88 impinges the front pane 72a in an angle
which is outside the acceptance angle, the light ray 88 travels through the
liquid 78 and
the first plate 62a until reaching the boundary between the first plate and
the air gap 64.
This time, since the impinging angle at the boundary between the first plate
and the air
gap 64 is smaller than the critical angle, a total internal reflection does
not occur. Thus,
the light ray 88 travels through the air gap 64 the second plate 62b out
through the rear
pane 72b.
It will be appreciated that differences between the refractive indices of the
first
plate 62a and the air gap 64 may cause the light ray 88 passing therethrough
to slightly
deviate, in accordance with Snell's law. As a result, the image formed when
looking
through the window 70 from the side of the rear pane 72b may be distorted.
However,
since the light ray 88 than travels through the second plate 62b having a
refractive index
larger than that of the air inside the gap 64, thereby the light ray is
shifted back to
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substantially its original path thus, allowing the formation of a clear image
on the other
side of the window 70.
Reference is now made to Figs. 4A and 4B, a PV assembly 36 having a first PV
cell 38a and a second PV cell 38b disposed adjacent one another and between a
front
and rear pane 35a and 35b, having being liquid 37 therebetween. Each PV cell
38a and
38b is provided with a separator 39a and 39b disposed in an angle a with
respect to the
front pane 35a, and in an angle /3 with respect to the associated PV cell 38a
and 38b,
respectively. The PV cells 38a and 38b limit the viewing angle, as some of the
entering
rays of light are blocked by the surface of the PV cells 38a and 38b. As
clearly shown
in Fig. 4A, for a viewer 33, located relatively far from the window, the
viewing cone 32
through two adjacent PV cells 38a and 38b is determined approximately by the
far
edges thereof. The direction of the viewing cone 32 is determined by a central
ray 34,
which extends perpendicular from the viewer's eye. Thus, if the viewer looks
through
the window in a straight line, the central ray 34 is perpendicular to the rear
pane 35b.
The viewing cone 32 in that case is limited by the first PV cell 38a disposed
above the
central ray 34 and the second PV cell 38b disposed below the central ray 34.
If for
example, the viewer looks downwardly, the image which he will see may include
rays
blocked by the edge of the PV cells 38a and 38b, and at this angle the viewer
will not
be able to see clearly through the window.
However, as shown in Fig. 4B the direction of central ray 34 and consequently
of the viewing cone 32 can be controlled. This is carried out by tilting the
PV cells 38a
and 38b together with the respective separators 39a and 39b, thereby allowing
a
downwardly tilted viewing cone (looking down for a viewer looking from the
left side
of the window). It should be noted that while tilting the PV cell does not
reduce the
optical efficiency of the optical liquid elements, it does however change the
level of
concentration. That is to say, for a horizontally disposed PV cell the level
of
concentration is calculated as 1where a is the angle between the
separators 39a,
tan(a)
39b and the inner layer of the front pane 35a. When the PV cell 38a is tilted
downwardly in an angle of J3 the concentration level is calculated as sin(fi)+
cos(fl) .
tan(a)
It is appreciated that the window can include a stationary PV assembly,
wherein
the PV cell is disposed in an angle selected in accordance with the desired
direction of
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the viewing cone. For example, for a window which is disposed in a high place
allowing
the viewer to look downwardly therethrough, the PV cells can be disposed in a
downward slope (with respect to the viewer and the rear pane of the window)
thereby
forming a downwardly viewing cone. This way, the viewer can look through the
window without the interference of the PV cells. On the other hand, when the
window is
configured to allow a viewer to look forward, the PV cells can be horizontally
disposed
thereby forming a straight forward viewing cone allowing the user to clearly
see
through the window when looking forward.
According to another example, the PV assembly can be a dynamic system
allowing the viewing cone to be adjusted as desired. An Example of such system
is
described here in after with regards to Figs. 6A through 6C.
It is noted that normally a double glazed window is provided with a space in
between, which is filled with air or other gas, providing a layer of
insulation. However
according to the presently disclosed subject matter the space between the
front and rear
pane contains the PV assembly which includes mostly optical liquid, dividers
and PV
cells, resulting in a high thermal conductively, thus compromising insulation.
During use, some of the solar radiation which reaches the array of PV cells is
converted into electrical energy. However, a non-significant amount is
converted into
heat, raising the temperature of the cells. Depending on the design thereof,
dependent
on, inter alia, its construction and the materials it comprises, the separator
may begin to
undergo deformation at elevated temperatures, for example at temperatures
above 90 C-
150 C. In addition, the efficiency of the PV cells decreases with increasing
temperature.
Thus, the window may comprise one or more heat dissipation arrangements, as
described in WO 2011/048595. However, it is appricatead that the liquid inside
the
window can be configured to dissipate heat to the glass.
Fig. 5 shows a double glazed window 90 having a front pane 92a and a rear pane
92b and a PV assembly 94 disposed therebetween. According to this example, the
double glazed window further includes an insulation layer for insulating the
interior of
the window form the exterior thereof. The insulation layer can be in the form
of a cavity
96 defined between front pane 92a and a rear pane 92b containing air, gas, or
vacuum
for providing thermal and/or acoustical insulation. The cavity 96 is defined
by one of
the window's panes, here illustrated as the rear pane 92b and an intermediate
divider 98.
The intermediate divider 98 includes first face 98a defining the space for the
PV
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assembly 94, and a second face 98b defining the cavity 96. Accordingly, the
first face
98a serves as the inner surface of the rear pane of the previous examples, and
is
configured to hold the liquid and the PV assembly 94, as explained hereinabove
with
regards to Fig. 4C. It is appreciated that the divider 98 need not necessarily
be glass and
in fact in order to reduce both width and weight of the window 90, it may be
made of
any other transparent material. In addition, the divider 98 can includes a low
emissivity
coating for example on the inner surfaces thereof
According to one example, the rear pane 92b and/or the front pane 92a are
sealingly coupled to the divider 98 by means of frames 100a and 100b. Thus,
frame
100a holds rear pane 92b on one side thereof and the divider 98 on the other
side
thereof, thereby defining the cavity 96. Frame 100b on the other hand, holds
front pane
92b on one side thereof and the divider 98 on the other side thereof, whereby
defining
the end surface of the PV assembly. It is appreciated that the cavity 96 can
alternatively
be defined between the front pane 92a and the divider 96, and according to
this
example, the PV assembly can be mounted in between the divider 96 and the rear
pane
92b were the liquid is held.
Frames 100a and 100b which can be made of aluminum, and which is attached
to the front and rear panes as well as to the divider 98 with an adhesive
material 102,
such as Butyl adhesive, and can be further strengthened by a strong and
elastic
adhesive, such as Silicone based adhesive. The frame 100a can be perforated
from
inside and filled with desiccant material 104, so as to reduce the amount of
humidity
entering in between the panes 92a and 92b of the window 90 thereby increasing
the
product lifetime and the PV system durability. It will be understood that the
use of the
desiccant material 104 is relevant to the frame 100a holding the divider 98
and the rear
pane 92b and defining cavity 96. The frame 100b which holds the PV assembly 94
contains the liquid therein, thus no humidity can enter inside.
Fig. 6A through 6D illustrates a double glazed window 110 having a front pane
112 and a rear pane 114, and a PV assembly 116 mounted therebweteen. PV
assembly
116 according to this example is a dynamic system and is provided with an
adjusting
mechanism allowing the user to adjust the angle of the PV cells and/or the
separators
thereby adjusting the viewing cone of the viewer and the amount of light which
can
travel through the window. Adjusting the angle of the PV cells and the
separators can be
carried out by a single adjusting maechism or by two separated mechanisms.
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According to an example, the PV assembly 116 includes a plurality longitudianl
PV arrays 118 each disposed along one dimension of the window 110, for
example, its
width, and comprises a plurality of PV cells. The PV arrays 118 according to
this
example are arranged one beneath the other such as venetian blinds. The PV
assembly
116 further includes a plurality of corresponding longitudinal separators 120
each
associated with one PV cell or with one array of PV cell and configured for
directing
some light rays thereto as explained hereinabove with respect to the previous
examples.
The separators are disposed in an angle a with respect to the front pane 112,
and in an
angle /3 with respect to the associated PV array 118. The PV arrays and the
separators
are coupled to one another by means of a suspension cord 122, extending
through an
apertures 124 and 126 formed in each PV array 118 and each separator 120,
respectively. The suspension cord 122 allows pulling the PV arrays together
with their
respective separators upwardly by reducing the distance between each adjacent
PV
array 118, and reducing angles a and /I as shown in Fig, 6c. The suspension
cord 122
can be provided with in any actuating mechanism (not shown) for example, a
cord
provided outside the rear pane 114 which by pulling thereof the PV assembly is
folded
upwardly, such as used for the folding of venetian blinds. It is appreciated
however, that
in order to allow folding the PV array 118 and each separator 120, the space
between
the front pane 12 and the rear pane 14 may be adapted accordingly, so as to
accommodate the separators even when horizontally disposed.
According to an example, the suspension cord can be further configured to
electrically couple the PV arrays to one another.
According to one example, the PV assembly 116 is further provided with an
adjusting mechanism (not shown) allowing the adjustment of angles a and /I
without the
suspension of the PV arrays 118 and the separators 120. Adjusting the angles a
and /3
can be carried out by adjusting cords, as used for adjusting the angle of
venetian blinds,
which can be pulled to rotate each PV array 118 and the separators 120.
Alternatively,
an adjusting gearing system (not shown) can be provided at the side frame of
the
window holding the front and rear pane 112, and 114, to which the PV arrays
and the
separators are coupled. The gearing system can be activated to rotate the PV
arrays and
the separators as desired.
It is appreciated that the adjusting mechanism can be configured to allow
adjusting either the angle a or the angle /3, or both. This way, when for
example the
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angle a is reduced the acceptance angle O. is reduced as well (in accordance
with the
abovementioned formula), thus less light ray will be reflected toward the PV
cells
resulting in more light entering the building. This can be carried out for
example in the
winter when more light and heat from the sun is desired.
On the other hand, changing the angle fl allows changing the direction of the
viewing cone and the field of vision, as explained hereinabove with regards to
Figs. 4A
and 4B.
Fig. 2 provides an example of how an appropriate acceptance angle 0a may be
selected. Based on the latitude at which the window 10 will be installed, the
maximum
zenith angle (i.e., the largest angle from the vertical which the sun will
make over the
course of the year) is found. If "all year shading" is desired, i.e., if no
direct sunlight
should be admitted via the window, the acceptance angle (4, should be chosen
to be
equal to the extreme zenith angle (bearing in mind that sunlight impinging
within the
acceptance angle is accepted by the PV cell 18, and does not pass through the
window).
If "adaptive shading" is desired, i.e., if direct sunlight should be admitted
only when the
sun is at lower elevations, for example during the winter or morning and
afternoons/evening during the summer, the acceptance angle 0a should be chosen
to be
somewhat lower than the extreme zenith angle. In such a case, the lower the
acceptance
angle, the more sunlight will be admitted via the window 10.
Those skilled in the art to which the presently disclosed subject matter
pertains
will readily appreciate that numerous changes, variations, and modifications
can be
made without departing from the scope of the invention, mutatis mutandis.
