U.S. patent application number 12/750769 was filed with the patent office on 2010-09-23 for device for collecting solar radiation.
Invention is credited to Harald HAUF, Sothachett VAN.
Application Number | 20100236540 12/750769 |
Document ID | / |
Family ID | 39321514 |
Filed Date | 2010-09-23 |
United States Patent
Application |
20100236540 |
Kind Code |
A1 |
HAUF; Harald ; et
al. |
September 23, 2010 |
DEVICE FOR COLLECTING SOLAR RADIATION
Abstract
A device for collecting solar radiation without guiding the
orientation thereof relative to the sun position is disclosed. The
device includes at least one photovoltaic solar collector having a
face sensitive to the solar radiation, at least one reflecting
surface for reflecting the solar radiation towards the sensitive
face of the collector, and an orientation apparatus for supporting
the solar collector. The orientation apparatus providing an
orientation and an inclination to the sensitive face of the
collector in relation to the reflecting surface. The reflecting
surface is conformed so that, at least during predetermined periods
of a day and at least during predetermined days of a year, solar
radiation reflected by the reflecting surface reaches the sensitive
face of the solar collector with a minimized angle of incidence
when the device is arranged in a predetermined orientation.
Inventors: |
HAUF; Harald; (La Seyne Sur
Mer, FR) ; VAN; Sothachett; (Le Versoud, FR) |
Correspondence
Address: |
PANITCH SCHWARZE BELISARIO & NADEL LLP
ONE COMMERCE SQUARE, 2005 MARKET STREET, SUITE 2200
PHILADELPHIA
PA
19103
US
|
Family ID: |
39321514 |
Appl. No.: |
12/750769 |
Filed: |
March 31, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/IB2008/002538 |
Sep 24, 2008 |
|
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|
12750769 |
|
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Current U.S.
Class: |
126/600 ;
126/684 |
Current CPC
Class: |
Y02E 10/52 20130101;
F24S 2023/86 20180501; H02S 20/00 20130101; H01L 31/0547 20141201;
F24S 25/67 20180501; F24S 23/80 20180501; Y02E 10/47 20130101 |
Class at
Publication: |
126/600 ;
126/684 |
International
Class: |
F24J 2/38 20060101
F24J002/38; F24J 2/10 20060101 F24J002/10 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 2, 2007 |
FR |
07 58011 |
Claims
1. A device for collecting solar radiation without guiding the
orientation thereof relative to the sun position, the device
comprising: at least one photovoltaic solar collector having a face
sensitive to the solar radiation; at least one reflecting surface
configured to reflect the solar radiation towards the sensitive
face of the collector; and an orientation apparatus supporting the
solar collector, the orientation apparatus providing an orientation
and an inclination to the sensitive face of the collector in
relation to the reflecting surface, the reflecting surface being
conformed such that, at least during predetermined periods of a day
and at least during predetermined days of a year, solar radiation
reflected by the reflecting surface reaches the sensitive face of
the solar collector with a minimized angle of incidence when the
device is fixedly arranged in a predetermined orientation in
relation to Earth.
2. The device according to claim 1, wherein the at least one solar
collector is of longitudinal shape and has a longitudinal axis
thereof oriented approximately in a North-South direction.
3. The device according to claim 1, wherein the at least one solar
collector is of longitudinal shape and the reflecting surface has,
in a section plane perpendicular to a longitudinal axis of the
collector, a first profile with no vertical axis of symmetry.
4. The device according to claim 3, wherein the at least one solar
collector is of longitudinal shape and the reflecting surface has,
in a longitudinal section plane parallel to a longitudinal axis of
the collector, a second profile with no vertical axis of
symmetry.
5. The device according to claim 4, wherein the sensitive face of
the at least one solar collector is disposed above a longitudinal
edge of the at least one reflecting surface with a predetermined
inclination angle.
6. The device according to claim 1, wherein the at least one solar
collector is of longitudinal shape, the device further comprising
first and a second reflecting surfaces symmetrically arranged
relative to a longitudinal plane of the device.
7. The device according to claim 6, wherein the sensitive face of
the at least one solar collector is arranged above a longitudinal
junction area of the first and second reflecting surfaces.
8. The device according to claim 6, further comprising first and
second solar collectors of longitudinal shape, the first solar
collector having a sensitive face thereof directed towards the
first reflecting surface with a first inclination angle, the second
solar collector having a sensitive face thereof directed towards
the second reflecting surface with a second inclination angle.
9. The device according to claim 1, further comprising a cavity
receiving the at least one reflecting surface and wherein the at
least one solar collector is fixed on a support projecting into the
cavity.
10. The device according to claim 1, further comprising a cavity
receiving the at least one reflecting surface and a cover
transparent to the solar radiation, covering the cavity.
11. The device according to claim 10, wherein the at least one
solar collector is fixed on the cover.
12. The device according to claim 1, wherein a projection of the
surface of the at least one solar collector into a plane above the
device, is between about 5% and 30% of the projection of the at
least one reflecting surface into the same plane.
13. The device according to claim 1, further comprising a coupling
apparatus configured to fix the device to at least one of another
adjacent device or a structure.
14. The device according to claim 1, further comprising an
electrical connector configured to link the solar collector to an
exterior of the device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of International
Application No. PCT/IB2008/002538, filed Sep. 24, 2008, which was
published in the French language on Apr. 9, 2009, under
International Publication No. WO 2009/044247 A2 and the disclosure
of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Embodiments of the present invention relate to the field of
devices for collecting solar radiation. Nowadays, the devices
generally used are arranged in flat panels integrating solar
collectors transforming solar energy into electrical energy. The
collection ability, and therefore the electrical efficiency, of
such panels directly depend on the surface of the sensitive face
directly exposed to the sun of the solar collectors, and on the
orientation of this face in relation to the solar radiation.
[0003] Embodiments of the invention more particularly relate to a
device for collecting solar radiation, including at least one
photovoltaic solar collector having a face sensitive to the solar
radiation, at least one reflecting surface for reflecting the solar
radiation towards the sensitive face of the collector, and means
for maintaining the solar collector which determine the orientation
of the sensitive face of the collector in relation to the
reflecting surface.
[0004] Devices of the aforementioned type are referred to as
"concentrating photovoltaic panels". In a photovoltaic solar
module, the most expensive component is the photovoltaic collector.
Interposing a concentrator device between the sun and the collector
makes it possible to use a photovoltaic collector with a smaller
surface, for the benefit of the cost price of the module. The
concentration is generally obtained by a system of parabolic
mirrors with solar tracking.
[0005] The drawback of concentrating photovoltaic panels is that
the angle of incidence of the solar light must be very low so that
such panels operate properly only with a system for guiding the
panels in relation to the sun travel, generally called solar
tracking, so that the panels remain perpendicular to the reflected
sun radiation.
[0006] U.S. Pat. No. 2,919,298 suggests, for example, to provide a
plurality of cup shaped paraboloid mirrors having one focal point
and imperatively requiring, due to the shape of the cups and their
unique focal point, a system for guiding the cups in relation to
the sun so that the solar light vertically reaches the cups, as it
is shown in FIG. 1.
[0007] U.S. Pat. No. 4,337,758 also describes a photovoltaic device
provided with a paraboloid mirror with a complex surface requiring
guiding in relation to the sun.
[0008] European Patent Publication No. EP 347 443 also describes a
solar module with multiple mirrors and multiple solar collectors of
the "double face" type, the mirrors being in the shape of grooves
with parabolic profiles and thus requiring, to be efficient, that
the solar light has a low angle of incidence in relation to the
solar module.
[0009] Japanese Patent Publication No. JP 2001-127331 also
describes a solar panel comprising double face solar collectors,
the lower face of which receives solar radiation reflected by flat
reflectors (FIG. 1b) or cup shaped reflectors (FIG. 3). As
previously, such a solar panel requires a controlled orientation
and must receive the solar light perpendicularly to the surface
thereof to yield a satisfying energetic efficiency.
[0010] Canadian Patent Publication No. CA 2 428 578 also describes
a device including a reflector in aluminum of paraboloid concave
shape which is almost entirely covered with double face
photovoltaic cells of pyramidal shape. The solar radiation can
penetrate into the reflector cup only by the edges of the device,
which are provided with a small amount of reflective mercury to
that end.
BRIEF SUMMARY OF THE INVENTION
[0011] Embodiments of the invention more particularly relate to a
photovoltaic device using a reflecting surface, which may be used
without guiding the orientation thereof in relation to the sun
position.
[0012] One embodiment of the invention thus provides a device for
collecting solar radiation without guiding the orientation thereof
relative to the sun position. The device includes at least one
photovoltaic solar collector having a face sensitive to the solar
radiation, at least one reflecting surface for reflecting the solar
radiation towards the sensitive face of the collector, and an
orientation apparatus supporting the solar collector. The
orientation apparatus provides an orientation and an inclination to
the sensitive face of the collector in relation to the reflecting
surface. The reflecting surface is conformed so that, at least
during predetermined periods of a day and at least during
predetermined days of a year, solar radiation reflected by the
reflecting surface reaches the sensitive face of the solar
collector with a minimized angle of incidence when the device is
fixedly arranged in a predetermined orientation relative to
Earth.
[0013] According to one embodiment, the solar collector is of
longitudinal shape and the reflecting surface is conformed so that,
at least during some periods of a day and at least during some days
of the year, reflected solar radiation reaches the sensitive face
of the solar collector with a minimized angle of incidence for an
approximate North-South orientation of the longitudinal axis of the
solar collector.
[0014] According to one embodiment, the solar collector is of
longitudinal shape and the reflecting surface has, in a section
plane perpendicular to the longitudinal axis of the collector, a
first profile with no vertical axis of symmetry.
[0015] According to one embodiment, the solar collector is of
longitudinal shape and the reflecting surface has, in a
longitudinal section plane parallel to the longitudinal axis of the
collector, a second profile with no vertical axis of symmetry.
[0016] According to one embodiment, the sensitive face of the solar
collector is disposed above a longitudinal edge of the reflecting
surface with a determined inclination angle.
[0017] According to one embodiment, the solar collector is of
longitudinal shape, and the device includes first and second
reflecting surfaces symmetrically arranged relative to a
longitudinal plane of the device.
[0018] According to one embodiment, the sensitive face of the solar
collector is arranged above a longitudinal junction area of the
first and second reflecting surfaces.
[0019] According to one embodiment, the device includes first and
second solar collectors of longitudinal shape, the first solar
collector having its sensitive face directed towards the first
reflecting surface with a first inclination angle, the second solar
collector having its sensitive face directed towards the second
reflecting surface with a second inclination angle.
[0020] According to one embodiment, the device includes a cavity
receiving the reflecting surface and the solar collector is fixed
on a support projecting into the cavity.
[0021] According to one embodiment, the device includes a cavity
receiving the reflecting surface and a cover transparent to the
solar radiation, covering the cavity.
[0022] According to one embodiment, the solar collector is fixed on
the cover.
[0023] According to one embodiment, the projection of the surface
of the solar collector into a plane above the device is between
about 5% and 30% of a projection of the reflecting surface into the
same plane.
[0024] According to one embodiment, the device includes a coupling
apparatus configured to fix the device to at least one of another
adjacent device or a structure.
[0025] According to one embodiment, the device includes an
electrical connector configured to link the solar collector to an
exterior of the device.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0026] The foregoing summary, as well as the following detailed
description of the invention, will be better understood when read
in conjunction with the appended drawings. For the purpose of
illustrating the invention, there are shown in the drawings
embodiments which are presently preferred. It should be understood,
however, that the invention is not limited to the precise
arrangements and instrumentalities shown.
[0027] In the drawings:
[0028] FIG. 1 shows a cross section of an embodiment of a device
according to the invention;
[0029] FIG. 2 shows a magnified cross section of the central part
of the device of FIG. 1;
[0030] FIG. 3 is a top view of the device of FIG. 1;
[0031] FIG. 4 shows a magnified cross section of the lateral part
of the device of FIG. 1;
[0032] FIG. 5 shows a longitudinal section along V-V of the device
of FIG. 1;
[0033] FIG. 6 is a variation of fixation of the device of FIG.
1;
[0034] FIG. 7 shows another embodiment of the device of FIG. 1;
and
[0035] FIG. 8 shows a cross section of another embodiment of a
device according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0036] A device 1 is shown with reference to FIGS. 1 to 5, for
collecting solar radiation, which includes a base 2 in the shape of
parallelepiped cup, which has a bottom 3 and a peripheral wall 4,
which has two opposite longitudinal sides 5 and two opposite
transversal sides 6, and which includes a rectangular flat cover 7,
a peripheral edge of which is fixed on the peripheral edge of the
peripheral wall 4, preferably in an impermeable way, so that the
base 2 and the cover 7 delineate a cavity 8.
[0037] The cover 7 is made from a material transparent to solar
radiation, for example, glass or plastic. The device 1 includes a
longitudinal support 9 projecting into the cavity 8, which is fixed
on the longitudinal median part of the bottom 3 of the cup 2. The
longitudinal support includes a rectangular plate 10 extending
towards the cover 7 and two symmetric opposite longitudinal
rectangular flanges 11 and 12 fixed longitudinally on the free edge
of the plate 10. The flanges spread longitudinally, approximately
up to the opposite transversal sides 6 of the base 2 and
transversely, in the direction of the opposite longitudinal sides 5
of the base 2 by being leant towards the cover 7 from the free edge
of the plate 10.
[0038] The device 1 includes longitudinal flat solar collectors 15
and 16, which are fixed on the internal faces 13 and 14 of the
leant flanges 11 and 12, opposite to the cover 7. The collectors
include photovoltaic modules having faces sensitive to the solar
radiation directed inwardly and having the inclinations of the
flanges 11 and 12.
[0039] The device 1 includes two elements 17 and 18 which are fixed
to the base 2 at the bottom of the cavity 8 which occupy in width
and length the spaces between the plate 10 and the peripheral wall
4 of the base 2.
[0040] The elements 17 and 18 have reflecting frontal surfaces 19
and 20, which are located at a distance from the cover 7 and the
collectors 15 and 16.
[0041] The reflecting frontal surfaces 19 and 20 are formed so as
to reflect, at least partially, the solar radiation passing through
the cover 7 respectively towards the sensitive faces of the
collectors 15 and 16. The reflecting frontal surfaces 19 and 20 are
preferably symmetric relative to the plate 10 of the support 9, to
thus place the longitudinal plane of the device approximately in a
plane passing through the North and South poles of Earth.
[0042] Preferably, the shape of the reflecting frontal surfaces 19
and 20 is adapted so that the angles of incidence of the solar
radiation reflected reaching the sensitive faces of the collectors
15 and 16 are, to some extent, for at least some periods of the day
and/or the year, as small as possible.
[0043] The width of the flanges 11 to 12, projecting towards the
cover 7 or projecting on a plane extending above the device, may
include between five and thirty percent of the width of the cavity
8. Consequently, the surface of the solar collectors 15 and 16 is
approximately in the same ratio in relation to the surface of the
projections of the reflecting surfaces 19 and 20 on the cover
7.
[0044] The device 1 includes electrical connectors configured to
connect the solar collectors 15 and 16 to the exterior, which
include wires 21 which spread along the support 9 and go outwardly
passing through an orifice 3a of the bottom 3 of the base 2.
[0045] According to one embodiment, the base 2 may be in a metal
plate which does not oxidize or which is protected against
oxidation, and the cover 7 may be fixed on the base 2 by a
peripheral adhesive and sealing joint 22. It may be noted that the
cavity 8 is sealed and only linked to the exterior or to the air
through the rear orifice 3a for routing the wires 21.
[0046] The elements 17 and 18 may include blocks, for example made
of a foam plastic, covered with a layer or a sheet, for example
metallic, and the reflecting surfaces 19 and 20 may include this
layer or sheet by depositing thereon a layer of a reflecting
material, such as silver, aluminum or zinc.
[0047] The result is that the device 1 may advantageously
constitute a construction element. The aforementioned blocks may be
stuck onto the bottom 3 of the base 2.
[0048] As it is shown in particular in FIG. 4, feet 23 and screws
24 may be used to fix the bottom 3 of the base 2 of the device 1 to
a rear support structure 25. Likewise, two devices 1 may be coupled
using, for example, feet 26 and screws 27, allowing their adjacent
peripheral edges to be linked. Panels of several devices 1 may thus
be made at will.
[0049] As it is shown in FIG. 6, it is also possible to form feet
23a so that two rows of devices 1 are parallel and not located in a
same plane, so as to adapt the orientation thereof relative to a
particular support structure to get the nearest possible to the
best orientation in relation to the light radiation.
[0050] According to the variation shown in FIG. 7, the elements 17
and 18 are replaced by shaped plates 28, peripheral edges of which
are fixed flat on the internal wall of the base 2 and on the
support 9, for example with screws 29. The shaped plates 28 and 29
may, for example, be metallic or of rigid plastic and their
reflecting surfaces 28a may include a deposit thereon of a layer of
a reflecting matter such as silver, aluminum or zinc.
[0051] The result of the aforementioned description and in
particular of the cross section view of FIG. 1 and the longitudinal
section view along V-V of FIG. 5, is that the embodiment which has
just been described of the device 1 according to the invention is
equivalent to the juxtaposition of two "half-devices" arranged side
by side, wherein a first half-device includes the solar collector
15 and the reflecting surface 19, and a second half-device includes
the solar collector 16 and the reflecting surface 20. Both
reflecting surfaces 19, 20 are indeed arranged symmetrically
relative to a longitudinal plane of the device (shown here by the
vertical rectangular plate 10), and the sensitive face of each
solar collector 15, 16 spreads here above a longitudinal edge of
the corresponding reflecting surface 19, 20 with an inclination
angle which is determined by the orientation of the flanges 11 and
12.
[0052] As it was indicated above, each respective reflecting
surface 19, 20, is conformed so that, at least during some periods
of a day and some days of the year, solar radiation reflected by
the reflecting surface reaches the sensitive face of the
corresponding collector 15, 16, with an angle of incidence as small
as possible when the device is arranged according to a
predetermined orientation, for example, with its longitudinal axis
arranged in a North-South direction, as indicated above.
[0053] In accordance with the properties of photovoltaic
collectors, such an optimization of each reflecting surface 19, 20,
to reduce as much as possible the angle of incidence of the light
radiation of the sun relative to the sensitive face of each
collector 15, 16, yields a better energetic efficiency of the
collectors. A "better energetic efficiency" here refers to the fact
that more electrical energy is supplied by the collector by unit of
photovoltaic surface during preferred periods of the day and the
year (periods for which the reflecting surfaces have been
optimized), in relation to a collector which is arranged facing a
reflecting surface of paraboloid type not optimized to be used
without guiding the device relative to the sun travel. In other
words, embodiments of the present invention provide to globally
optimize the yearly energy supplied by the collector, i.e., the sum
of all the electrical powers supplied U(t)*I(t) by the collector,
instead of searching to obtain a supplied power U(t)*I(t) which is
maximal in optimal conditions of use, requiring a tracking of the
sun travel.
[0054] Thus, the device 1 has a lower cost price than that of a
conventional solar panel, since the surface of the photovoltaic
collector only represents 5% to 30% of costly photovoltaic surface,
in relation to the photosensitive surface of a conventional
collector without concentration.
[0055] More particularly, the shape of each reflecting surface 19,
20 is optimized by calculating the integral of the power collected
during predetermined periods of the day and predetermined days of
the year, so that the result of the integral, i.e., the electrical
energy collected, is maximized, i.e., close to a maximum value. The
reference maximum for this optimization, in terms of yearly energy,
is, for example, the yearly energy supplied by a conventional flat
solar collector having the same inclination and orientation as the
device according to the invention, and with the same surface as the
surface of the base of the device (occupied surface).
[0056] The reflecting surface obtained 19, 20 is a not parabolic
shape due to the angles between reflected radiation and solar
collector which change anytime (each hour and all through the
year). It does not have a single focal point, but a plurality of
focal points, while performing a global or "statistical" function
of concentration of the solar light (yearly average), for a given
orientation of the device 1 relative to Earth and for a
predetermined orientation and inclination of the corresponding
solar collector 15, 16 relative to the reflecting surface.
[0057] As it is shown in FIG. 1, the result of the optimization is
that each reflecting surface 19, 20 may have, in a section plane
perpendicular to the longitudinal axis of the collector, a first
profile with no vertical axis of symmetry (the verticality being
determined in relation to the mounting plane of the base 2, which
cannot be horizontal in practice even if it is horizontal in FIG.
1). If the longitudinal orientation axis of the device 1 kept at
the time of the design of the reflecting surfaces 19, 20 is, for
example, the North-South axis, as indicated above, the reflecting
surface 19 may, for example, be optimized to send towards the solar
collector 15, with the smallest possible angle of incidence, the
solar radiation emitted by the sun when it is directed to the West
or South-West (i.e., in the afternoon in the North hemisphere), as
it appears in FIG. 1. Reciprocally, the reflecting surface 20 may
be optimized to send towards the solar collector 16, with the
smallest possible angle of incidence, the solar radiation emitted
by the sun when it is directed to the East or South-East (i.e., in
the morning in the North hemisphere), as it also appears in FIG.
1.
[0058] The optimization of each reflecting surface 19, 20 may also
result in each reflecting surface also having, in a longitudinal
section plane parallel to the longitudinal axis of the collector,
such as the section plane V-V, a profile without vertical axis of
symmetry (relative to the mounting plane of the base 2), aiming to
optimize the energetic efficiency taking into account the fact that
the angle of the sun at noon differs according to the periods of
the year.
[0059] In addition, those skilled in the art will understand that
such an optimization of each reflecting surface must be made taking
into account the position and orientation of the solar collector
15, 16 relative to the reflecting surface to be optimized 19, 20.
In the embodiment shown in FIGS. 1 to 5, each solar collector has a
predetermined inclination, imposed by the arrangement of the
flanges 11 and 12. In an embodiment described hereinafter, the
inclination angle is different, and consequently, the optimized
shape of the reflecting surfaces may differ.
[0060] In practice, various arrangements of each solar collector in
relation to the corresponding reflecting surface may be provided to
facilitate the optimization of the reflecting surface. The
optimization therefore relates to a couple of parameters including
on the one hand, the shape of the reflecting surface and on the
other hand, the orientation of the solar collector relative to the
reflecting surface, for a given orientation of the device (for
example, North-South). FIG. 1 shows that the arrangement of each
solar collector 15, 16 relative to the corresponding reflecting
surface 19, 20 is such that the solar collector is not arranged in
a focal point of the reflecting surface during most hours of
collection of the solar energy. This arrangement of collector
relative to the reflecting surface is inherent to the fact that
there is no sun tracking.
[0061] FIG. 8 shows a device 34 which differs from the device 1 in
that the support 9 is suppressed. The device 34 includes a
longitudinal flat solar collector 35 which is fixed flat on the
internal face of the cover 7 and the sensitive face of which is
turned on the side of the bottom of the base 2. It also includes
two symmetric reflecting elements 36 and 37, which preferably cover
the whole bottom of the base 2.
[0062] Thus, in this embodiment, the sensitive face of the
longitudinal solar collector 35 is arranged above the longitudinal
junction area of the first and second reflecting surfaces 36, 37.
In accordance with the embodiment of FIG. 1, it may also be
possible to provide two solar collectors, each being longitudinally
arranged above a longitudinal edge of one of the reflecting
surfaces.
[0063] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. It is
understood, therefore, that this invention is not limited to the
particular embodiments disclosed, but it is intended to cover
modifications within the spirit and scope of the present invention
as defined by the appended claims.
* * * * *