Electrical connections to solar cells in a module are made at the same time the cells are encapsulated for protection. The encapsulating material is embossed to facilitate the positioning of the cells during assembly

Anagnostou, E.

Forestieri, A. F.

English

NASA Technical Reports Server

United States Patent [19] 
Anagnostou et al. 
[111 4,083,097 
[45] Apr. 11, 1978 
[54] METHOD OF MAKING ENCAPSULATED ~561 References Cited 
U.S. PATENT DOCUMENTS SOLAR CELL MODULES 
[75] Inventors: 
[73] Assignee: 
[21] Appl. No.: 
[22] Filed: 
Evelyn Anagnostou, Westlake; 
Americo F. Forestieri, Berea, both of 
Ohio 
The United States of America as 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
746,269 
Nov. 30,1976 
2,919,298 12/1959 Regnier et al. .................. 136/89 PC 
2,962,539 11/1960 Daniel ............................. 136/89 TF 
3,255,047 6/1966 Escoffery ........................... 29/572 X 
3,268,366 SA966 Guyot .............................. 136/89 PC 
3,780,424 12/1973 Forestieri et al. ..................... 29/572 
OTHER PUBLICATIONS 
IBM Tech. Disclosure Bulletin, vol. 4, No. 11, Apr. 
1962, p. 62, Crawford et al., “Pluggable Solar Cell”. 
Primaiy Examiner-Carl E. Hall 
Attorney, Agent, or Firm-N. T. Musial; J. R. Manning; 
G. E. Shook 
1571 ABSTRACT 
Electrical connections to solar cells in a module are 
[51] Int. Cl.2 ............................................. HOlL 37/00 
[52] U.S. (3. ........................................ 29/572; 29/628; 
136/89 P; 136/89 H 
[58] Field of Search ............... 29/572, 628; 136/89 R, 
136/89 P, 89 H, 89 PC, 89 TF 
made at the same time the cells are encapsulated for 
protection. The encapsulating material is embossed to 
facilitate the positioning of the cells during assembly. 
6 Claims, 4 Drawing Figures 
https://ntrs.nasa.gov/search.jsp?R=19780017585 2020-03-20T13:29:48+00:00Z
U.S. Patent April 11, 1978 4,083,097 
FIG.  I 
26 
I 
14 
I 3" 4P 34 36 
20 
FIG. 2 I6 32 
_ _  
FIG.  4 
FIG. 3 
1 
4,083,097 
2 
METHOD OF MAKING ENCAPSULATED SOLAR 
CELL MODULES 
STATEMENT OF GOVERNMENT OWNERSHIP 
The invention described herein was made by employ- 
ees of the United States Government and may be manu- 
factured or used by or for the Government without the 
payment of any royalties thereon or therefor. 
BACKGROUND OF THE INVENTION 
This invention is directed to an improved low cost 
solar cell module. The invention is particularly con- 
cerned with making an encapsulated solar cell module 
having improved electrical contacts. 
The electrical contacts to solar cells in modules must 
be sturdy to withstand handling. These contacts are 
presently made individually and in a separate operation. 
This contacting process is tedious and time-consuming. 
Such a process is also costly because it requires much 
handling of the cells and contacts. Another disadvan- 
tage is the contact must be thicker than necessary which 
is wasteful of the material. 
U.S. Pat. No. 2,919,298 to Regnier et al teaches the 
mounting of solar cells in parabolic depressions of me- 
tallic sheet which is used as a reflector. The cells are 
then covered with a thermoplastic sheet containing 
conductive strips therein to make the necessary connec- 
tions. 
U.S. Pat. No. 3,025,330 to Ralph shows a plurality of 
solar cells embedded in a non-conductive panel. The 
cells are connected together by two flexible metal films 
separated by a flexible insulating layer. The electrical 
connections and the encapsulation are not accomplished 
in a single step. 
U.S. Pat. No. 3,268,366 to Guyot teaches the mount- 
ing of cells in a grid which enables connections to be 
made by any known means including printed circuitry. 
After the connections are made, a window is mounted 
over each cell. The finished array has three surfaces 
including a front window, grid and back metal surface. 
U.S. Pat. No. 2,962,539 to Daniels discloses the 
mounting of solar cells in depressions on a flexible sheet 
which serves as a mounting platform. Printed circuitry 
may be used for the connections. 
OBJECTS OF THE INVENTION 
It is, therefore, an object of the present invention to 
provide an encapsulated solar cell module that has im- 
proved electrical contacts. 
Another object of the invention is to provide an im- 
proved process for making an encapsulated solar cell 
module which is less costly and make electrical contact 
during encapsulation. 
Still another object of the invention is to provide an 
improved solar cell module in which solar cells of vari- 
ous configurations can be used with only slight modifi- 
cation. 
A further object of the invention is to provide an 
improved solar cell module in which the embossing 
depth may be modified so that a variety of cells of vari- 
ous thicknesses can be handled or used. 
An additional object of the invention is to provide an 
improved process for encapsulating cells into modules 
with less handling so that the process is suitable for 
automation. 
These and other objects of the invention will be ap- 
parent from the specification which follows and from 
the drawing wherein like numerals are used throughout 
to identify like parts. 
SUMMARY OF THE INVENTION 
The problems of the prior art have been solved by 
utilizing the method of the present invention in which 
solar cells are encapsulated in a plastic material. The 
encapsulating material is embossed to enable the cells to 
be readily positioned for final encapsulation. The elec- 
10 trical connections to the solar cells are made at the same 
time the cells are encapsulated. 
5 
DESCRIPTION OF THE DRAWINGS 
FIG. 1 is a perspective view with parts broken away 
of a solar cell module constructed in accordance with 
the invention; 
FIG. 2 is a vertical section view taken along the line 
2-2 in FIG. 1; 
FIG. 3 is a plan view of a back plastic sheet hving 
FIG. 4 is a vertical section view similar to FIG. 2 
2o printed circuitry thereon, and 
showing an alternate embodiment of the invention. 
DESCRIPTION OF THE PREFERRED 
25 EMBODIMENT 
Referring now to the drawing there is shown in FIG. 
1 a sheet 10 of transparent plastic material which is 
utilized as a cover. A fluorinated ethylene propylene 
copolymer film described in U.S. Pat. No. 2,946,763 has 
30 been suitable for this purpose. This film is known com- 
mercially as Teflon FEP, and it is an interpolymer of 
tetrafluoroetylene and hexafluoropropylene. It is fur- 
ther contemplated that other clear film may be used. 
According to the presknt invention, a flat sheet of this 
fluorinated ethylene propylene copolymer is heated and 
pressure molded to form an embossed surface having a 
plurality of depressions 12 arranged in rows. Each de- 
pression 12 has the same configuration as a solar cell, 
40 and each cover sheet 10 has as many depressions in an 
array of adjacent rows as are required for the particular 
application. 
The depth of each depression is sufficient to position 
the solar cell. The depth of the depression will depend 
45 on the material used in the cover sheet 10. More partic- 
ularly, the amount of material flow during lamination or 
fabrication is a determining factor in designing the 
depth of the depressions 12. 
Referring to FIGS. 1 and 2, a plurality of solar cells 
50 14 are placed in the depressions 12. Each depression 
contains one solar cell having its first surface 16 in 
contact with the sheet 10. Thus, the front surface 16 of 
the solar cell 14 which is to face the light source 
contacts the bottom of the depression 12. 
Solar cells 14 with positive and negative contacts on 
the back surface 18 are preferred. These contacts 20 and 
22 are shown in FIGS. 1 and 2. N on P cells are pre- 
ferred for space applications. With this type of cell the 
contact 20 is positive and the contact 22 is negative. 
60 With P on N cells the contacts 20 and 22 are negative 
and positive respectively. 
A second sheet of fluorinated ethylene propylene 
copolymer 24 shown best in FIG. 3 has the required 
interconnecting circuitry metalization 26 on it. The 
65 sheet 16 is likewise an interpolymer of tetrafluoroethyl- 
ene and hexafluoroethylene, as described in U.S. Pat. 
No. 2,946,763. It is also contemplated that other materi- 
als may be used. 
35 
55 
4,083,097 
3 4 
Metal films 26 forming the circuitry can be much 
thinner than contacts now in use. By way of example, 
the conventional contacts presently used are about 1 to 
positioning a back cover over said solar cells in 
contact with the back surfaces thereof opposite 
said front surfaces, and 
said transparent cover to said back cover. 
2 mils thick, In contrast, the print& circuit contacts of 
the Present invention are less than about 4 mil' Thv 
electrically connecting said solar cells while securing 
2. A method of making a module of solar 
5 
as films are so positioned on the sheet 24 that each electri- 
row to the contacts 22 on the cells in an Bdjacent row. 
the depressions 12 in a sheet 10 as shown in FIG. 1. The 
assembly is then laminated to insure a good FEP bond. 
During this step the electrical connections are made by + 
thermal compression bonding. 
DESCRIPTION OF AN ALTERNATE 
in claim wherein the transparent is 
Calh Wnnects the contacts 20 on the cells l4 in One embossed to form a plurality of depressions in an array 
of rows, 
3. A method of making a module of solar cells as 
claimed in claim 2 wherein each solar cell has both 
positive and negative electrical contacts on said back 
surface thereof opposite said front surface including the 
steps of 
forming a plurality of metal films on said back cover 
prior to positioning the same over said solar cells, 
EMBODIMENT and 
positioning said back cover over said solar cells so 
that said metal films electrically connect the 
contacts on all the cells in one row to the contacts 
on the cells in an adjacent row. 
4. A method of making a module of solar cells as 
claimed in claim 3 including the steps of 
laminating said transparent cover to said back cover 
while simultaneously forming electrical connec- 
tions between adjacent solar cells by compression 
bonding. 
5* A meth& of making a module of solar cells 
wherein each solar cell has one contact on the front 
30 surface thereof and another contact on the back surface 
thereof comprising the steps of 
The plastic sheet 24 is placed over the solar cells 14 in 10 
15 
Referring now to FIG. 4 there is shown an embodi- 
ment utilizing solar cells 34 having conventional front- 2o 
back contacts. A cover sheet 30 of Teflon FEP or the 
like is embossed to form depression 32 in the same man- 
ner as used to form the depressions 12 in the cover shtet 
10. 
circuitry metalktion is on both the cover sheet 30 as 
well as a backing sheet 36. A metal contact 38 is formed 
on each depression 32 in the cover sheet 30 before the 
solar cell 34 is placed therein. A mea am 40 on the 
backing sheet 36 connects the contacts 38 in each row 
with the back surface of the solar cells in adjacent rows. 
The electrical connections are made by sintering upon 
assembly. 
shown and described it will be appreciated that various 
modifications may be made to the invention without 
departing from the spirit of the invention or the scope of 
the subjoined claims. By way of example, the electrical 
connections may be made using printed circuits in both 40 
the cells and the back cover. 
In the embodiment of FIG. 4 the interconnecting 25 
forming a plurality of depressions in a 
forming a first metal film in each depression, 
cover, 
While a preferred example of the invention has 35 placing a solar cell in each of said depressions so that 
the front surface of the solar cell which is to re- 
ceive light faces the bottom of said depression and 
contacts said fust metal film, 
forming a Plurality of scamI metal films on said back 
cover, and 
positioning said back cover over said solar cells so 
that said second metal films electrically connect 
the first metal films on all the depressions in one 
row to the back surface contacts on all the c 
What is claimed is: 
1. A method of making a module of solar cells having 
forming a plurality of depressions in said transparent 
cover, 
Placing a solar cell in each of said depressions so that 
the front surfaces of the solar cells which are to 
face a light source contact the bottoms of said 50 
depressions, 
45 an adjacent row. a transparent cover comprising the steps of 
6. A method of making a module of solar 
laminating said transparent cover to said back cover 
while simultaneously forming electrical connec- 
tions between adjacent solar cells by sintering. 
claimed in claim 5 including the steps of 
* * * * *  
5s 
60 
65 


Method of making encapsulated solar cell modules

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