Note: Descriptions are shown in the official language in which they were submitted.
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1 This invention relates to a system for col-
2 lecting solar energy, concentrating it and transmitting
3 it to a point of use in the form of light.
4 Commercially available solar collectors typical-
ly convert solar radiation incident on a generally wide
6 area to electrical or thermal energy which is subsequently
7 transported in the converted form to a point of use.
8 Because of some of the inherent practical and technical
9 limitations of large area solar conversion devices,
attempts have been made to concentrate the solar radiation
11 impinging over a wider area and focusing it onto a smaller
12 area conversion device. Among the typical solar energy
13 concentrators employed are mirrors, lenses and fluorescent
14 devices.
In U.S. Patent 668,404, use of a mirror for
16 focusing solar ra~iation onto a point of use is disclosed.
17 A more recent solar concentrator based on the use of re-
18 flecting solar radiation with mirrors and focusing it at
19 a collection ~oint is disclosed in U.S. Patent 4,130,109.
Since the relative position of the sun and earth changes
21 with time, there are certain practical limitations with
22 respect to using mirrored surfaces for focusing solar
23 radiation at a point of use.
24 In U.S. Patent 4,148,300 and U.S. Patent
4,114,592, lens type devices are disclosed for focusing
26 solar radiation on a point of use. As undoubtedly will
27 be appreciated, high quality lenses for such applications
28 are expensive and consequently are not suitable to ex-
29 tremely widespread use.
In U.S. Patent 4,175,980 and U.S. Patent
31 4,149,902, there are described different types of fluo-
32 rescent concentrators in which solar radiation is col-
33 lected over large flat areas and focused onto a smaller
34 area for the photovoltaic conversion of the focused radi-
ant energy means of a photovoltaic device. Indeed, in
36 U.S. Patent 4,149,902, the photovoltaic device is contigu-
37 ous with the fluorescent collector. In one embodiment
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1 of U.S. Patent 4,175,980, however, the photovoltaic
2 device is not contiguous with the fluorescent concentrator
3 but is separated from the concentrator by means of a fiber
4 optic mechanism. In the former patent, however, the amount
of light utilized is limited by the cross-sectional area
6 of the solar cell and, in the latter patent, the amount
7 of light utilized is limited by the cross-sectional area
8 of the fiber optic mechanism.
9 According to this invention, there is provided a
system for the collection of electromagnetic radiation
11 and the transmission of that radiation to a point of
12 utilization in the form of light. Basically, the system
13 employs a first solar concentrator for the collection and
14 concentration of solar radiation. Optically coupled to
the first solar concentrator is at least one additional
16 solar concentrator for further concentrating the collected
17 solar radiation for efficient coupling with a light pipe.
18 Thus, the light pipe directs the collected and concentrated
19 light to a point of utilization. Preferably, the solar
concentrators are planar fluorescent solar concentrators
21 having different fluorescent materials in each concentra-
22 tor.
23 The precise characteristics and features of the
24 invention will become more readily apparent from the
following detailed description when read in light of the
26 accompanying drawings.
27 Fig. 1 is a schematic isometric drawing of one
28 embodiment of the present invention.
29 Fig. 2 is a schematic illustration of a fluo-
rescent planar concentrator useful in the solar system
31 of the present invention.
32 Fig. 3 is a sectional view taken along lines 3-
33 3 of Fig. 2.
34 Fig. 4 is a schematic illustration of one con-
nector device used in the system of the present invention.
36 Fig. 5 is a sectional view taken along lines 5-
5 of Fig. 4.
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1 Fig. 6 is a schematic illustration of yet
2 another connector device used in the practice of the
3 present invention.
4 Turning now to Fig. 1, the system for the col-
lection of solar radiation and its transmission to a point
6 of utilization according to the present invention includes
7 a solar energy receiver 10 op~ically coupled to means 11
8 for further concentrating the collected solar radiation
9 and transmitting it to a light transmission pipe 12 for
transmission to a point of use designated generally as 14.
11 In operation, incident solar radiation desig-
12 nated by line 16 is received in the collector 10 and con-
13 centrated and transmitted as shown by line 17 to the
14 second stage concentrator 11 where the light is further
concentrated and transmitted as shown by line 18 to light
16 pipe 12. The light emanating from light pipe 12 and shown
17 generally as line 19 is delivered to a point of utiliza-
18 tion 14.
19 Basically, the solar energy receiver 10 can be
any one of the known devices for the reception of incident
21 solar radiation and its concentration such as planar con-
22 centrators, mirrored reflectors, parabolic troughs, and
23 the like. In the practice of the present invention,
24 however, it is particularly preferred that the solar col-
lector 10 be a fluorescent planar concentrator. These
26 fluorescent planar concentrators are known in the art.
27 They consist, for example, of layers of dyes on light
28 transparent slabs of material or consist of glass contain-
29 ing fluorescent chelates, certain inorganic ions and the
like. Thus, as is shown in Fig. 3, for exa~ple, solar
31 collector 10 consists of a layer of fluorescent material
32 20 which is optically coupled to a sheet of highly light
33 transparent material 21 such as glass or plastic. Thus,
34 the collector 10 has a major surface 22 for the reception
of incident solar radiation. The side walls 23 and end
36 wall 24 are preferably coated with a light reflecting
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1 material, such as aluminum, silver and the like. Also,
2 bottom surface 25 is coated with a light diffusive materi-
3 al such as white paint and, preferably, a light reflective
4 material. Thus, as can be seen in Figs. 1 and 2, the
incident solar radiation 16 is internally reflected by
6 means of the mirrors on light reflective surfaces and the
7 fluorescent material 20 and is redirected so as to exit
8 the collector at unmirrored end wall 26.
9 As can be seen in Fig. 1, optically connected
to end wall 26 of solar collector 10 is connector means 11
11 ~for optically connecting the first stage concentrator to
12 a light pipe. The connector 11 also further concentrates
13 the solar radiation as well as serves to transmit it to
14 the light pipe 12. Basically, the connector means 11 for
further concentrating the solar radiation is a second
16 stage concentrator which may be based upon reflectors,
17 parabolic troughs and the like, but preferably the second
18 stage solar concentrator is a fluorescent planar concen-
19 trator (see Figs. 4 and 5) consisting largely of a fluo-
rescent material 27 having light reflective surfaces on
21 the top and bottom 28 and 29 of the concentrator, respec-
22 tively, as well as end wall 30 and side wall 31. The
23 fluorescent material of the second stage concentrator, of
24 course, must be a different fluorescent material from the
fluorescent material in the first fluorescent concentrator,
26 i.e., it must absorb solar radiation in a different region
27 of the spectrum. Both concentrators may employ dyes,
28 chelates or inorganic ions, however.
29 Returning to Figs. 1 and 4, connector means 11
has a side wall 32 which is adapted to be optically coupled
31 to the edge of collector concentrator 10 for the reception
32 of solar radiation from collector 10 for further concen-
33 tration in connector 11. The connector or second stage
34 concentrator additionally has an unmirrored side wall 33
for optical coupling to a light transmission pipe 12.
36 In the embodiment shown in Fig. 6, the second
37 stage concentrator has a geometry designed to enhance the
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1 concentration being achieved via the fluorescent mecha-
2 nism thereby further reducing the area for light to be
3 emitted-from for coupling to the light pipe 12.
4 As will be appreciated, the light transmission
pipe 12 or optical waveguide is one which is normally
6 employed in conventional fiber optic techniques and,
7 indeed, would typically be a plurality of such fibers.
8 However, a single conventional light pipe may be used in
9 the practice of the present invention.
As is indicated in Fig. 1, 14 represents a
11 point of utilization. As will be readily appreciated,
12 the light emanating from light pipe 12 and shown as line
13 19 can be projected onto a photoresponsive device such
14 as a photovoltaic cell for direct conversion of the light
incident on the cell to electrical energy. Optionally
16 and preferably, the point of utilization will include a
17 heat exchanger having a selective surface thereon for
18 converting fluid in heat exchange relationship with the
19 heat exchanger to thermal energy.
As will be readily appreciated, control means
21 (not shown) can be employed to switch the light at the
22 point of use so as to limit the amount of thermal energy
23 generated in the thermal conversion device or the tempera-
24 ture reached when power is not required.
The invention has been described in detail with
26 particular reference to preferred embodiments thereof,
27 but it will be understood that reasonable variations and
28 modifications are possible without departing from the
29 spirit and scope of the invention.
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