4,182,308 Solar energy collector

Patent Number/Link:

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

7/1977

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

[54)

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[73]

[21]

[22]

[51]

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U.S. Patent Jan. 8, 1980 Sheet 1 of 3 4,182,308

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FIG I

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u.S. Patent Jan. 8, 1980 Sheet 2 of 3 4,182,308

FIG 2

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OUTLET

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FIG 3

u.s. Patent Jan. 8, 1980 Sheet 3 of 3 4,182,308

FIG 4

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4,182,308

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

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

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.

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

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

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.

* * * * *