Solar cell submodules with bus bars that leave tabs along one end of the submodule and wires with raised portions along the other end are assembled by interlocking the tabs and wires of adjacent submodules. This structural design is lightweight and reliable and requires no metallic substructure

Yasui, R. K.

English

NASA Technical Reports Server

Module 
Positive Bus Wire 
May 1966
	 Brief 66-10231 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Solar Cell Submodule Design Facilitates Assembly of Lightweight Arrays 
The problem: 
• To design a solar cell submodule that can easily be 
assembled into lightweight arrays of high reliability. 
Solar cell submodules, when assembled into arrays, 
have required a metallic substructure to increase the 
mechanical strength of the arrays. The substructure 
increases the weight of the assembly and the complex-
ity of the fabrication process. Previous practice has 
also required troublesome reheating of the soldered 
ohmic contacts on individual solar cells in order to 
assemble parallel and series arrays.
The solution: 
Fabricate submodules using bus bars that leave tabs 
along one end of the submodule and wires with raised 
portions along the other end. The submodules can be 
interlocked by bending the tabs on one submodule 
around the bus wire of an adjacent submodule. 
How it's done: 
The photovoltaic solar cells are made of type P on 
N silicon, with three grids along their length and the 
P contact across one end. The N contact covers the 
entire rear surface of the cell. The ohmic contacts are 
(continued overleat) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
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applied by using a photoresist masking process and 
electroless nickel plating. The nickel-plated ohmic 
contacts are solder-dipped (60 Sn-40 Pb) to facilitate 
cell interconnections and reduce contact resistance. 
Microsheet glass, with a filter deposited on the surface 
closest to the light-sensitive surface of the cell, is 
attached to the cell with a silicone adhesive. 
Submodules are comprised of several solar cells 
placed parallel to each other with the P contacts in 
line. The negative bus bar is soldered on the back sides 
of the cells at the edge opposite the positive terminals. 
A piece of wire is bent and spot-soldered to the posi-
tive terminals. The wire is bent to leave 1/32-inch-high 
openings spaced along the length of the wire and di-
rectly opposite the tabs protruding from the negative 
bus bar. 
When more voltage than that provided by a single 
submodule is required, two or more submodules may 
be connected in series by bending the negative tabs of 
one submodule around the positive bus wire of 
another submodule. 
Notes: 
I. Defective submodules can easily be removed from 
adjacent submodules. 
2. Submodules can be assembled with glass filter 
covers mounted, electrically measured, and visually
inspected prior to panel fabrication. This proce-
dure minimizes uncertainties in electrical mis-
matching between cell matrices. Final module 
interconnection is accomplished without applying 
heat to the ohmic solder contacts, normally the 
weakest link. 
3. Submodules can be assembled using a semiauto-
matel soldering system. 
4. The submodule structure is both lightweight and 
reliable and requires no metallic substructure to 
increase its mechanical strength. 
5. In the case of N on P silicon cells, vapor deposited 
silver and titanium ohmic contacts may be prefer-
'able. 
6. Inquiries concerning this invention may be di-
rected to:
Technology Utilization Officer 
Jet Propulsion Laboratory 
4800 Oak Grove Drive 
Pasadena, California, 91103 
Reference: B66-10231 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C., 20546. 
Source: Robert K. Yasui 
(J PL-728) 
Brief 66-10231	 Category 02


Solar cell submodule design facilitates assembly of lightweight arrays

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