U.S. patent application number 09/808399 was filed with the patent office on 2001-09-27 for method of fastening a solar cell to a support, especially a structure.
Invention is credited to Boe, Hans Peter.
Application Number | 20010023704 09/808399 |
Document ID | / |
Family ID | 8168190 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010023704 |
Kind Code |
A1 |
Boe, Hans Peter |
September 27, 2001 |
Method of fastening a solar cell to a support, especially a
structure
Abstract
A solar cell having a rear backing of a polyvinylfluoride foil
is bonded by a mortar consisting of a finely divided neutral
aggregate, a hydraulic cement and an aqueous dispersion of a
polyacrylic acid derivative having a logarithmic decrement of
torsional vibration damping with a maximum at a temperature below
0.degree. C. to the surface of a building composed of concrete, to
a porous glass or to a metal plate which is hung on a building.
Inventors: |
Boe, Hans Peter;
(Oberhausen, DE) |
Correspondence
Address: |
THE FIRM OF KARL F ROSS
5676 RIVERDALE AVENUE
PO BOX 900
RIVERDALE (BRONX)
NY
10471-0900
US
|
Family ID: |
8168190 |
Appl. No.: |
09/808399 |
Filed: |
March 14, 2001 |
Current U.S.
Class: |
136/251 ;
136/256; 438/64; 438/66 |
Current CPC
Class: |
C04B 2111/00637
20130101; C04B 40/0675 20130101; Y02B 10/12 20130101; C04B 24/2641
20130101; Y02B 10/10 20130101; C04B 2111/00612 20130101 |
Class at
Publication: |
136/251 ;
136/256; 438/64; 438/66 |
International
Class: |
H01L 021/00; H02N
006/00; H01L 025/00; H01L 031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 22, 2000 |
EP |
00106219.9 |
Claims
I claim:
1. A method of fastening to a support a solar cell having a front
glass plate and a rear backing of a polyvinylfluoride foil, said
method comprising the steps of: (a) preparing a bonding composition
from a hydraulic cement, a finely divided neutral aggregate and an
aqueous dispersion of a polyacrylic acid derivative having a
logarithmic decrement of torsional vibration damping, determined in
accordance with German Industrial Standard DIN 53445, having a
maximum at a temperature below 0.degree. C.; (b) applying said
bonding composition between said rear backing of polyvinylfluoride
foil of said solar cell and a support surface; and (c) permitting
said bonding composition to set, thereby bonding said
polyvinylfluoride-foil backing of said solar cell to said support
surface.
2. The method defined in claim 1, further comprising the step of
coating said polyvinylfluoride-foil backing of said solar cell with
a layer of a hydration-water hardened substance, said layer of said
hydration-water hardened substance having a hydration water
deficiency and being later bonded to said support surface by the
bonding composition by steps (a), (b) and (c).
3. The method defined in claim 2 wherein said support surface is
formed by a concrete building structure, said support surface being
formed with a recess, said solar cell being seated in said
recess.
4. The method defined in claim 2 wherein said support surface is
formed as a surface of a glass-foam structure and said
polyvinylfluoride-foil backing of said solar cell is bonded to said
glass-foam structure.
5. The method defined in claim 2 wherein said support surface is a
surface of a sheet metal support, said method further comprising
the step of bending a hanger tongue out of said sheet metal support
and affixing said sheet metal support with said solar cell bonded
thereto by said composition and said polyvinylfluoride-foil backing
of said solar cell to a building structure by said hanger
tongue.
6. The method defined in claim 5, further comprising bending a lip
of said sheet metal support forwardly to engage said solar cell
from below.
7. The method defined in claim 1 wherein said support surface is
formed by a concrete building structure, said support surface being
formed with a recess, said solar cell being seated in said
recess.
8. The method defined in claim 1 wherein said support surface is
formed as a surface of a glass-foam structure and said
polyvinylfluoride-foil backing of said solar cell is bonded to said
glass-foam structure.
9. The method defined in claim 1 wherein said support surface is a
surface of a sheet metal support, said method further comprising
the step of bending a hanger tongue out of said sheet metal support
and affixing said sheet metal support with said solar cell bonded
thereto by said composition and said polyvinylfluoride-foil backing
of said solar cell to a building structure by said hanger
tongue.
10. The method defined in claim 9, further comprising bending a lip
of said sheet metal support forwardly to engage said solar cell
from below.
11. A solar cell assembly comprising: a structure formed with a
support surface; a solar cell having a front glass plate and a rear
backing of a polyvinylfluoride foil; and a bonding composition from
a hydraulic cement, a finely divided neutral aggregate and an
aqueous dispersion of a polyacrylic acid derivative having a
logarithmic decrement of torsional vibration damping, determined in
accordance with German Industrial Standard DIN 53445, having a
maximum at a temperature below 0.degree. C. bonding said
polyvinylfluoride foil to said surface.
12. The solar cell assembly defined in claim 11, further comprising
a layer of a hydration-water hardened substance between said foil
and said surface.
13. The solar cell assembly defined in claim 11 wherein said
support surface is formed by a concrete building structure, said
support surface being formed with a recess, said solar cell being
seated in said recess.
14. The solar cell assembly defined in claim 11 wherein said
support surface is formed as a surface of a glass-foam structure
and said polyvinylfluoride-foil backing of said solar cell is
bonded to said glass-foam structure.
15. The solar cell assembly defined in claim 11 wherein said
support surface is a surface of a sheet metal support having a
hanger tongue bent out of said sheet metal support and affixing
said sheet metal support with said solar cell bonded thereto by
said composition and said polyvinylfluoride-foil backing of said
solar cell to a building structure by said hanger tongue.
16. The solar cell assembly defined in claim 15, further comprising
a lip of said sheet metal support bent forwardly to engage said
solar cell from below.
Description
FIELD OF THE INVENTION
[0001] My present invention relates to a method of fastening a
solar cell to a support, especially a surface of a building
structure. The invention also relates to a solar cell assembled on
a building structure or the like and to a mounting system for a
solar cell of the type which has a front glass plate and a rear
backing in the form of a polyvinylfluoride foil.
BACKGROUND OF THE INVENTION
[0002] The art does not appear to describe any bonding agent or
adhesive which is capable of satisfactorily bonding
polyvinylfluoride foils to optional support surfaces of structure
and the like, especially concrete structures, in a permanent
manner. A number of solar cells do provide, however, backing layers
of polyvinylfluoride foils. As a consequence, to mount such solar
cells on building structures it has been the practice heretofore to
secure the solar cells in a metal frame and then to mount this
metal frame on the structure. This approach is relatively
expensive.
[0003] EP 0 790 370 A discloses a bonding of a solar cell with a
front glass plate by bonding a mortar layer which is composed of a
finely divided neutral aggregate, cement (especially hydraulic
cement) and an aqueous dispersion of a polyacrylic acid derivative
in which the suspension serves to provide water for hydrating the
hydraulic cement and aggregate mixture. The polyacrylic acid
derivative has a logarithmic decrement of the torsional vibration
damping, determined by the German Industrial Standard DIN 53445,
which is a maximum at a temperature below 0.degree. C. This bonding
composition or mortar serves to secure the solar cell to a support
surface by a rear glass plate which must be provided over the
polyvinylfluoride foil or other foil structure of the solar cell.
As far as I am aware, there has been no adhesive or other bonding
agent described heretofore for securing the polyvinylfluoride foil
directly to a support surface.
OBJECTS OF THE INVENTION
[0004] It is therefore the principal object of the present
invention to provide an improved method of bonding the
polyvinylfluoride backing foil of a solar cell to a support
surface.
[0005] Another object of the invention is to provide a method of
mounting a solar cell which is less expensive than earlier mounting
methods and obviates drawbacks thereof.
[0006] A further object of the invention is to provide an improved
solar cell assembly.
SUMMARY OF THE INVENTION
[0007] These objects are attained in accordance with the invention
by a method of fastening to a support a solar cell having a front
glass plate and rear backing of a polyvinylfluoride foil and which
comprises the steps of:
[0008] (a) preparing a bonding composition from a hydraulic cement,
a finely divided neutral aggregate and an aqueous dispersion of a
polyacrylic acid derivative having a logarithmic decrement of
torsional vibration damping, determined in accordance with German
Industrial Standard DIN 53445, having a maximum at a temperature
below 0.degree. C.;
[0009] (b) applying the bonding composition between the rear
backing of polyvinylfluoride foil of the solar cell and a support
surface; and
[0010] (c) permitting the bonding composition to set, thereby
bonding the polyvinylfluoride-foil backing of the solar cell to the
support surface.
[0011] It is indeed surprising that this kind of mortar can bond
not only glass but also polyvinylfluoride to surfaces like metal
surfaces and concrete surfaces of a structure satisfying all of the
requirements for mounting of solar cells in an exposed state. This
was certainly not to be expected since, while both
polyvinylfluoride and glass are practically impermeable to water
vapor, they have vastly different compositions and structures.
[0012] In a preferred embodiment of the invention, the back side of
the solar cell, i.e. the polyvinylfluoride foil, may be precoated
with a hardened layer of a mortar composition which hardens by
combination with water of hydration and under conditions of a water
of hydration deficiency. Later with the aid of a fresh bonding
mortar composition as described above, the deficiency layer and the
polyvinylfluoride foil are bonded to the surface of the support
which can be constituted of concrete and which may have a
cassette-like recess in which the solar cell is seated for
protection from external influences.
[0013] Solar cells based upon amorphous silicon have an efficiency
which increases with the temperature. In a preferred embodiment, to
insulate the solar cell and maintain an elevated temperature, the
solar cell is secured in accordance with the invention on a glass
foam substrate.
[0014] With solar cells of crystalline silicon, which have an
efficiency which increases as the temperature is reduced, the solar
cell can be secured to a sheet metal plate having a rearwardly bent
tongue which enables the plate to be hung on the wall of a
structure. The sheet metal plate to which the solar cell is bonded
has a forwardly bent lip at an edge engaging below the solar cell.
The finely divided neutral aggregate can have a grain size of 0.1
to 1 mm, preferably 0.2 to 0.7 mm. The cement can be a Portland
cement.
[0015] The polyacrylic acid derivative can be a polyacrylate,
especially an acrylic resin or a copolymer of polymers in which
acrylonitrile is one of the comonomers. The water content of the
dispersion serves as the water of hydration or setting the
composition and for completing the hydration if necessary of the
layer previously applied to the polyvinylfluoride foil.
BRIEF DESCRIPTION OF THE DRAWING
[0016] The above and other objects, features, and advantages will
become more readily apparent from the following description,
reference being made to the accompanying drawing in which:
[0017] FIG. 1 is a cross sectional view showing a first embodiment
of a solar cell bonded to a support; and
[0018] FIG. 2 is a cross sectional view of a second embodiment of
the solar cell.
SPECIFIC DESCRIPTION
[0019] The solar cells 1 shown in FIGS. 1 and 2 have a front side
formed with a glass plate 2 turned toward the sun and a rear
backing foil of polyvinylfluoride as shown at 3.
[0020] The backing foil 3 of polyvinylfluoride can have a mortar
layer 4 prebonded thereto and composed of a finely divided neutral
aggregate, cement and an aqueous dispersion of a polyacrylate acid
derivative which supplies make-up water for the composition. The
polyacrylic acid derivative can be a polymer of acrylic acid,
acrylates or acrylonitrile and may be a methacrylic acid polymer or
copolymer which has a logarithmic decrement of the torsional
vibration damping, determined in accordance with DIN 53445 which
has a maximum at a temperature below 0.degree. C. This mortar layer
4 is hardened with a deficiency of hydration water.
[0021] The layer 4 or the foil 3 directly is then bonded by a
further mortar layer, also constituted of the finely divided
neutral aggregate, the hydraulic cement and the aqueous dispersion
of the polyacrylic acid derivative to the support 7. The mortar
layer 5 is permitted to harden and can supply water of hydration in
an amount to make up for the deficiency in the layer 4.
[0022] In the embodiment of FIG. 1, the solar cell is bonded in a
cassette recess 6 of a building structure 7 of concrete. It is also
possible to use foamed glass as the support. In the embodiment of
FIG. 2 the solar cell 1 is bonded by the layer 5 of the mortar to a
sheet metal plate 8 which is stamped with a rearwardly bent hanger
tongue with which the assembly of FIG. 2 can be hung from the
structure 7. The sheet metal plate 8 has a forwardly bent lip 10
engaging below the lower edge of the solar cell.
[0023] The aggregate can be quartz sand or ground glass and in the
composition, the finely divided aggregate, the cement and the
aqueous dispersion of the polyacrylic acid derivative can each be
present in an amount of 10 to 40% by weight with each being present
in a preferred range of 25 to 35 weight percent. In a specific
example, the aqueous dispersion is present in an amount of 35%, the
Portland cement in an amount of 30% and the glass mail is present
in an amount of 35%. The layers 4 and 5 can be of a thickness of 2
to 7 mm, preferably 4 to 6 mm.
* * * * *