United States Patent (19]
Reynolds
(11]
[45]
4,182,308
Jan.S, 1980
SOLAR ENERGY COLLECfOR
Inventor: James E. Reynolds, Golden, Colo.
Assignee: Hazen Research, Inc., Golden, Colo.
3,908,631
3,987,783
4,015,586
4,018,213
4,036,209
4,082,082
4,085,734
4,091,800
ABSTRACf
18 Claims, 6 Drawing Figures
A solar energy collector which is inexpensive to manufacture
and install comprising a heat absorber unit of
rubber-like material having channels for the passage
therethrough of heat exchange fluid and spaced-apart
retainer means on its top for retaining a flexible solar
collector cover in a flexed configuration accomplished
by wedging it between the retainer means so that the
area of the insulating space between absorber and collector
can be controlled for different climates by spacing
the retainer means and a simple means for assembling
absorber and collector is provided. The collector
is adapted to be mounted on a base to form a modular
unit.
[57]
FOREIGN PATENT DOCUMENTS
2335804 7/1977 France 126/271
1157156 7/1969 United Kingdom 126/271
Primary Examiner-James C. Yeung
Attorney. Agent. or Firm-Sheridan, Ross, Fields &
McIntosh
Rom 126/270
Powell 126/271
Vroom et a!. 126/271
Mann, Jr 126/271
Press 126/271
Harvey 126/271
Gibbs 126/271
Fletcher et a!. 126/271
9/1975
10/1976
4/1977
4/1977
7/1977
4/1978
4/1978
5/1978
References Cited
U.S. PATENT DOCUMENTS
Appl. No.: 849,026
Filed: Nov. 7, 1977
Int. Cl,2 F24J 3/02
U.S. Cl 126/437; 165/171
Field of Search 126/270,271; 237/1 A;
165/48,49, 171, 172, 173
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[73]
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[22]
[51]
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30
U.S. Patent Jan. 8, 1980 Sheet 1 of 3 4,182,308
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FIG I
'II
u.S. Patent Jan. 8, 1980 Sheet 2 of 3 4,182,308
30
FIG 2
/'9 30) 32)
OUTLET
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~ INLET
FIG 3
u.s. Patent Jan. 8, 1980 Sheet 3 of 3 4,182,308
FIG 4
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FI G 5
29
FI G 6
4,182,308
1
SOLAR ENERGY COLLECfOR
BACKGROUND OF THE INVENTION
The widespread interest evidenced by both govern- 5
ment and industry today in developing an economical
solar energy collection system for residential heating is
well known. Substantial effort is being expended to
develop such a system, including systems for hot water
heating. The two main items of expense wherein im- 10
provements are necessary are in the initial manufacturing
cost of the solar collector system and the installation
cost.
Solar energy for supplemental hot water heating and
home heating awaits the development of a reliable, 15
reasonably efficient, inexpensive solar collector. Present
commercial units cost $1O-15/ft2 for the collector
and about $20/ft2 for the total installed cost, including
plumbing, storage, heat exchange, and the control system.
A typical home requires about 50-75 square feet 20
for hot water heating, or $1000-1500 installed cost and
one-third the heated floor space for forty percent supplemental
space heating, e.g., SX1500 ft2 home=
500X20=$10,000.
Obviously, few home owners are willing to invest 25
this amount of money for a 10-15 year payback in fuel
savings in view of the uncertainties of the energy situation,
alternate approaches to reducing home heating
costs such as insulation, and reports of the unreliability
and lower than expected thermal efficiencies of some 30
commercial solar units.
Accordingly, it is a principal object of this invention
to provide a solar energy collector which can be manufactured
from inexpensive materials by relatively inexpensive
mass production techniques, and which can be 35
readily installed by the home owner.
It is another object of this invention to provide a solar
energy collector· comprised of solar energy collector
cover and heat absorber which can be readily assembled
by the home owner simply by bowing the flexible col- 40
lector cover for insertion·between retainer elements
attached to the heat absorber to persent a convex
curved surface of the collector cover exposed to the
sunlight, provide aweather tight seal between collector
cover and heat absorber, and provide a means for ad- 45
justing the area of the insulating air space between collector
cover and heat absorber.
SUMMARY OF THE INVENTION
The invention is a solar energy collector comprising 50
a solar energy collector cover and a heat absorber. The
solar energy collector may optionally be mounted on a
base to provide a module. The collector cover is made
of a spectrally transparent material, preferably, of fiberglass
reinforced polyester and the heat absorber is made 55
of a rubber-like material such as "HYPALON" or chlorobutyl
rubber, these materials being relatively inexpensive.
The heat absorber is constructed of two plies of
material and channels for circulation of heat exchange
fluid are made therein by welding (thermal, adhesive or 60
otherwise) spaced-apart narrow strips so that .tubular
areas are left between the strips. The tubular areas communicate
at the ends of the heat absorber by spaces
which are made by leaving unwelded portions at the
ends of the alternate welded strips. The top ofthe .heat 65
absorber is provided with cover retaining means comprised
of longitudinal holding strips or flaps which are
spaced apart a distance on the heat absorber determined
2
by the area of the heat absorber desired to be covered
by the solar energy collector cover. Transverse distance
between the retainer strips or flaps is made less
than the width of the collector cover so that the flexible
collector cover must be bent or bowed for insertion of
its edges between the retainer strips so· that a curved
convex upper surface of the collector cover is exposed
to sunlight, a weather tight seal is provided between the
collector cover and the heat absorber, and a means is
provided for adjusting the distance between collector
cover and heat absorber and thereby controlling the
insulating space between collector and heat absorber
for different climates. A suitable base may be provided
to which the heat absorber is secured by an aluminum
foil upper surface of the base. The base may be of laminated
construction of insulating material, such as,
wood. The ends and sides of the lheat absorber are made
of sufficient length to extend down over the base and be
fastened there to provide a moisture proof structure to
protect the base and insulation from moisture.
BRIEF DESCRIPTION OF THE ORAWINGS
FIG. 1 is a schematic showing of a heating system for
a building incorporating the solar collector ofthe invention;
FIG. 2 is a cross-sectional view of the solar collector
of the invention mounted on its base, the drawing being
partially schematic;
FIG. 3 is a plan view of a cross-section of the heat
absorber unit of the solar collector;
FIG. 4 is a transverse cross-sectional view of an assembled
solar collector with the collector covers each
covering two channels of the heat absorber;
FIG. 5 is a transverse cross-sectional view like that of
FIG. 4 showing collector covers each covering three
channels of the heat absorber; and
FIG. 6 is a cross-sectional view of a modification of
the solar collector of the invention.
DESCRIPTION OF THE PREFERRED
EMBODIMENTS
The invention will now be described with reference
to the accompanying drawings. In the description amI
claims the terms "solar energy collector cover" and
"heat absorber" will be used to indicate, respectively,
the cover exposed to the sun through which solar energy
is transmitted and the unit which receives the
transmitted energy for transfer to the heat exchange
fluid. The term "solar energy collector" or "solar collector"
is used to indicate the Icombination of of the
solar energy collector cover and the heat absorber. The
term "base" designates the support upon which the
solar energy collector is mounted to form a module.
Referring to FIG. 1, numeral 10 refers generally to
the solar collector of the invention and the numeral 12
refers generally to a hot water tank for a residential
heating system connected to the solar collector by
means of cold water pipe 14 and! hot water return pipe
16. It will be seen that cold watler passes into the solar
collector 10 where it circulates through the channels to
be later described and after it has been heated, out
through the hot water pipe 16 back to the hot water
tank 12. The heated water can be used for various purposes.
For a more detailed description of the solar collector
unit reference is made to FIG. 2. As shown therein, the
solar collector comprises a base represented generally
4,182,308
3
at 36 upon which is secured in a manner to be described
later a heat absorber represented generally at 19 having
flow channels 20 through which water to be heated
passes as will be described hereinafter.
For collecting the sun's heat rays and transferring 5
them to the absorber, a spectrally transparent collector
cover 22 is mounted over the heat absorber 19 in a
manner to be described later. As shown in FIG. 2, the
collector assembly of heat absorber, and collector cover
is mounted on a laminated base comprising outdoor 10
plywood slab 24, dry wall slab 26 and Styrofoam insulator
slab 28. The complete unit including the solar collector
and the heat absorber mounted on the laminated
base may be mounted on a roof or other support for the
collection of heat rays. Other suitable structure may be 15
used for mounting the solar collector unit comprising
the cover and heat absorber where it will be exposed to
sunlight.
The solar panels or collector covers 22 are preferably
made of clear FRP polyester sheet specifically designed 20
for solar panel covers and is sold by Kalwall Corporation,
Manchester, New Hampshire under the trade
name "Sun-Lite". It is an acrylic modified, highly light
stabilized polyester which is reinforced with fiberglass.
Other resin-rich fiberglass reinforced materials may be 25
used for the collector units, such as fiberglass reinforced
polyester sheet. The units 22 are preferably flexible and
are secured at their longitudinal edges under longitudinally
extending cover retainer flaps 29 which are secured
to the heat absorber unit in a manner to be de- 30
scribed later. :
Reference is now made to FIG. 3 for a more detailed
description of the absorber unit 19. The unit is constructed
with a flat base or ply 30 to which is welded the
upper ply 32 of the absorber unit. Each ply is of rectan- 35
gular construction with sides and ends welded together
at their edges. The heat absorber unit is fabricated by
laminating two sheets of material together either by a
thermal or adhesive bond to weld the plies together in
an air mattress-type configuration. As shown in FIG. 2, 40
the plies are welded together longitudinally at the point
34 (FIG. 2) where spaces are left at alternate ends of the
weld seams to provide connecting conduits between the
channels 20 formed by the welded seams as shown in
FIG. 3. When water or other heat transfer fluid or air is 45
flowed through the unit, the unwelded portions will rise
to permit fluid to flow through the channels formed
between the welded seams. The term "fluid" is used
herein to mean liquid or gas. The bottom 30 is attached
to the laminated base (FIG. 2) by welding or otherwise. 50
Preferably, an aluminum foil 36 is secured on top of
Styrofoam sheet 28 to which heat absorber unit 19 is
secured. The absorber unit is secured over the Styrofoam
insulation 28 and the ends and sides of the bottom
ply 30 folded down around the insulation and base to 55
seal the edges of the base from moisture penetration.
The absorber unit also has adjacent oppositely extending
resilient retainer flaps 29 (FIG. 2) attached along the
length of the alternate flow channels. The flaps are for
securing the longitudinal edges of the solar collector 60
cover 22. These collector covers are wider than the
distance between retainer flaps and are bowed for insertion
to provide a tight fit under the retainer flaps. This
als.o provides an air gap above the absorber for insulation.
There is enough flex in the material of the collec- 65
tor cover units and resilience in the retainer strips to
provide a good weather-tight gasket-type seal between
the edges of the cover and the retainer flaps.
4
The absorber unit, including the base, is made of
reinforced "Hypalon", a material available on the market
and which is described in U. S. Pat. No. 2,046,090.
Other rubber-like material capable of holding up to 140·
F. water and sunlight for at least ten years may be used.
Other elastomeric or plastic-type materials which may
be used but which are not as satisfactory include carbon
black-filled polyethylene and polyvinylchloride; however
the service life of these two latter materials is too
short. Other materials which may be used for the collector
cover are acrylics and polyvinylfluoride.
In the modification shown in FIG. 4 a collector cover
is mounted over each adjacent pair of absorber channels
while FIG. 5 shows a modification in which a collector
cover is mounted over each group of three channels. Of
course, this construction is optional as the number of
channels covered by a collector cover can vary depending
upon the size of the unit. A futher modification is
shown in FIG. 6 in which a flat collector cover 38 is
mounted over the collector covers 22. This construction
has been found suitable for some applications. The
collector cover sheet 38 is of the same material as the
collector cover 22. The preferred material of the collector
cover of the described modification is referred to
herein and in the claims as an acrylic modified, fiberglass
reinforced polyester. This material has been found
to have suitable solar collector properties such as solar
energy transmission, and resistance to thermal degradation,
surface erosion, thermal shock and damage from
impact. "Sun-Lite" is an example of a suitable fiberglass
reinforced polyester which may be used as solar collector
cover material.
The heat absorber unit of the described modification
is fabricated by laminating two sheets of Hypalon together
using dielectric heating to weld the plies together
along narrow strips or lines in air mattress-type
configuration. The retainer strips are made integral
with the heat absorber by attaching one inch wide strip
of Hypalon along a length of alternate flow channels
and leaving a one-fourth flap on each side unattached
for securing the solar energy collector cover. This
method of manufacture is easily adaptable to assembly
line production.
As stated previously, the fiberglass reinforced'polyester
known as "Sun-Lite" meets the spectral, structural
and other properties required of material for a solar
energy collector cover. Because of the high impact
resistance and strength of this material, compared to
glass, much thinner sheets can be used for collector
covers. This, coupled with the lower density of this
material results in a reduction in shipping weight and
ease in handling and in assembly. Obviously, the care
required in handling glass panels to avoid breakage is
not necessary. A comparison of the manufacturing cost
and handling cost of this material with glass is very
favorable in favor of the Sun-Lite material.
The panel for a particular unit is cut to a required size
to give the necessary area of insulating space between
the cover and the heat absorber for different climates.
The width ofthecover panel will, of course, be greater
than the distance between the retaining means on the
top of the heat absorber. The cover is then inserted by
flexing it. outwardly and inserting its edges in the
spaced-apart retainer means. It is obvious from the description
that the distance between the cover and the
top of the absorber unit, and therefore the area of the
insulating air space, can be adjusted by adjusting the
width of the cover. It will be seen that the method of
4,182,308
5
inserting the cover securely over the heat absorber after
the materials have been shipped to the owner is simple
enough to permit installation by the owner.
A series of the outwardly curved collector covers
gives a scalloped appearance which is esthetic and does 5
not give the appearance of a greenhouse roof. The
curved plastic covers are structurally superior to flat
panes, for example, of glass. The impact resistance of
the material of the cover plates provides protection
from damage by hail or vandalism. The curved covers 10
provide a cellular-type cover which is effective in
breaking convection currents and reducing heat loss.
Holes in the collector surface can be readily repaired
with a plastic material patching kit.
The laminated base which has been described can be 15
purchased commercially under the trade name of "INSULWALL".
However, it can be readily manufactured
by assembly line production. After the base has been cut
to the correct size, the top layer of Styrofoam is covered
with aluminum foil and the absorber unit is bonded 20
to the aluminum foil with a conventional bonding material
for rubber-like material and aluminum. Edges are
left extending from the heat absorber which are folded
down around the ends and sides of the laminated base
and secured thereto to provide a moisture proof barrier. 25
The completed modules can be custom made and sold
for installation by the home owner. They can be made
flexible by modification of the base and insulation material
so that they will fit a curved roof or other complex
structures.
It can be seen from the above description that all of 30
the parts of the module can be constructed inexpensively
by mass production techniques and readily assembled
at low cost for shipment to the homeowner.
The unit can be readily installed by the homeowner.
The collector modules are portable so they can be taken 35
with the home owner if he moves. Because of the low
volume of heat exchange liquid, usually water or a
water solution, which is exposed to the atmosphere, less
antifreeze is required to keep the liquid from freezing.
The aluminum foil over the Styrofoam extends the life 40
of the rubber-like surfaces of the heat absorber. The
solar energy collector unit as well as the modular unit
with the base can be custom made to any length or
width requested. The configuration of the components
is such that they can be shipped in flat form thus reduc- 45
ing shipment costs.
It is seen from the above description that a solar energy
collector system has been provided which can be
manufactured inexpensively with inexpensive materials
by mass production techniques, and which can be in- 50
stalled cheaply by the home owner. Reliable estimates
show that the assembly can be fabricated for a total of
$3.23 per square foot so that two hot water collector
modules would cost $206.72 as compared to $768 for
two commercial models of comparable efficiency. 55
What is claimed is:
1. A solar energy collector for collecting and utilizing
solar energy comprising:
(a) at least one heat absorber including upper and
lower plies sealed together along spaced apart nar- 60
row longitudinal lines to provide channels between
said lines for passage of heat transfer fluids therethrough,
said channels being connected at their
alternate ends by spaces formed by alternate ends
of adjacent lines being left unsealed; 65
(b) at least one curved solar energy collector cover
mounted over the top of said heat absorber with its
upper convex surface facing outwardly and
6
(c) retainer means secured to the top of said heat
absorber for receiving longitudinal edges of said
solar collector cover to retain said solar collector
cover in operative position over said heat absorber,
said retainer means includes a flap-like strip of
resilient material secured along one of said narrow
longitudinal lines.
2. The solar collector of claim 1 in combination with
a heating system including means for circulating a heat
exchange fluid from said system through said channels
for absorbing heat from the heat absorber and back to
said system where said heat is utilized.
3. The solar collector of claim 1 in combination with
a base having a heat insulator top surface and the bottom
of said heat absorber being attached to said top
surface.
4. The solar collector of claim 3 in which said heat
insulator top surface is made of foamed plastic.
5. The solar collector of claim 4 in which said foamed
plastic is Styrofoam.
6. The solar collector of claim 5 in which said top
surface is mounted on a rigid sUiPport element.
7. The solar collector of claim 6 in which said rigid
support element is comprised of a slab of Styrofoam
laminated to a slab of drywall and a slab of plywood
laminated to said drywall slab.
8. The solar collector of claim 3 in which the ends of
said heat absorber are extended over the ends of said
base and secured to provide a moisture barrier for the
ends of said base.
9. The solar collector of claim 1 in which said retainer
means consists of two flap-like strips ofresilient material
secured along one of said narrow longitudinal lines
extending laterally in opposite directions for receiving
edges of adjacent solar collector covers.
10. The solar collector of claim 9 in which one of said
retainer means is secured along alternate ones of said
narrow transverse lines.
11. The solar collector of claim 1 in which said collector
cover is made of fiberglass reinforced polyester.
12. The solar collector of claim 11 in which the polyester
is acrylic modified.
13. The solar collector of claim 1 in which said solar
collector cover is flexible and wherein said retainer
means is spaced apart, the distance between said spaced
apart retainer means being less than the width of said
solar collector cover, whereby the latter must be bowed
for insertion into position between said spaced apart
retainer means so that the upper surface of said solar
collector cover exposed to sunlight is curved and the
solar collector cover is secured tightly between said
spaced apart retainer means.
14. The solar collector of claim 13 in which the distance
between said spaced-apart retainer means is adjusted
to provide an optimum space between the inner
surface of said solar collector cover and the top surface
of said heat absorber.
15. The solar collector of claim 14 in which said
distance is between about one-half to two inches.
16. The solar collector of claim 1 in which a solar
collector cover is mounted over each pair of said channels.
17. The solar collector of claim 1 in which a solar
collector cover is mounted over each group of four of
said channels.
18. The solar collector of claim 1 in which a flat plate
made of the same material as said solar collector cover
is mounted over the top of said solar collector cover.
* * * * *