Trade-off analysis and mathematical expressions calculate optimum grid geometry in terms of various cell parameters. Determination of the grid geometry provides proper balance between grid resistance and cell output to optimize the energy conversion process

Crossley, A. P.

English

NASA Technical Reports Server

Contact Strip 
Unit Field 
Grid Patte 
(S +T) xv
2
Grid Line 
October 1969	 Brief 69-10460 
S NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
-	 ---___ 
Optimizing Solar-Cell Grid Geometry 
Solar Cell And Contact Comb Geometry 
The relationship between maximum power output 
of photovoltaic devices and their surface grid struc-
tures is analyzed in an effort to optimize energy con-
version efficiencies. Results of this study are readily 
applicable to new types of solar cells, photodiodes and 
the general problem area of semiconductor-metal 
contacts. 
The problem: 
Most silicon solar cells are made with metallic grids 
in the form of combs to aid current conduction in the 
surface layer and to minimize power loss through
series resistance. However, these grids also shield 
the surface of the cell beneath them by intercepting 
the incident light and reducing the light-generated 
current. A method is required to determine the grid 
geometry to provide the proper balance between grid 
resistance and cell .output to optimize the energy con-
version process. 
The solution: 
A trade-off analysis is performed and mathematical 
expressions are derived to enable optimum grid geo-
metry to be calculated in terms of the various cell 
parameters.
(continued overkal( 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19690000448 2020-03-16T18:05:00+00:00Z
How it's done: 
The results of the analysis indicate that the width 
of each grid line, T, should be as small as fabrication 
technology will allow and that the optimum value of 
the grid aperture width, S, is a complex function of 
cell width, sheet resistance of the diffused region, and 
the voltage and current at the maximum power point. 
The overall width, W, and length, L, of the cell are 
usually determined by manufacturing convenience or 
application suitability, and the geometry of the con-
tact strip is fixed by considerations of contact relia-
bility. Parameters taken from conventional cell struc-
tures are introduced into the analysis and theoretical 
calculations made of optimum S values. Considering 
the complexity of the interrelated functions, a satis-
factory agreement is achieved when compared with 
experimental data.
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Headquarters 
National Aeronautics 
and Space Administration 
Washington, D.C. 20546 
Reference: TSP69- 10460 
Patent status: 
No patent action is contemplated by NASA. 
Source: Anthony P. Crossley of 
RCA 
Astro-Electronics Division 
under contract to 
NASA Headquarters 
(HQN- 10417)
. 
. 
Brief 69-10460	 Category 01


Optimizing solar-cell grid geometry

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server