Solar cell assembly current-voltage characteristics, thermal-optical properties, and power performance were determined. Solar cell cover glass thermal radiation, optical properties, confidence limits, and temperature intensity effects on maximum power were discussed

Cleland, E. L.

Jaworski, W.

Ross, R. G., Jr.

Wen, L.

Yasui, R. K.

English

NASA Technical Reports Server

December 1972
	 B72-10188 
•	 NASA TECH BRIEF 
NASA Pasadena Office	 4r 
NASA Tech Briefs announce now technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Performance of Silicon Solar Cell Assemblies 
PJ
The results of a comprehensive investigation of the 
actual performance of solar panels have been com-
piled in report form. The program of investigation 
was designed to assess the performance of three solar 
panel design approaches suitable for use at high solar 
intensities (Venus-Mercury flyby), but voluminous 
data in the report is of value to all users of solar cells, 
especially for design of terrestrial standby power sys-
tems which employ flat panels. 
Six types of solar cells and nine types of coverglass 
assemblies were selected for study of their electrical 
and thermal-optical properties. The solar cells were 
arranged in two major groups: (1) standard 2- and 10-
ohm-cm production cells, (2) experimental 2- and 10-
ohm-cm wide-grid cells with enlarged grid lines de-
signed to serve as second-surface mirrors. The cover 
glasses were arranged in three groups: (1) standard 
blue and blue-red interference filters and antireflective 
coatings on fused silica flats; (2) experimental selec-
tive-bandpass interference filters on fused silica; (3) 
experimental partially-mirrored coverglasses with blue 
filters and antireflective coatings. Assmblies were 
fabricated by cementing the glass covers to the cells 
with room-temperature-vulcanizable adhesive of the 
kind used in earlier space missions. 
The current-voltage characteristics of fourteen sil-
icon cell—cover glass combinations were determined 
at 25 temperature—incident energy combinations 
ranging from 40° to 160°C (in 20-degree incre-
ments) and 140 to 850 mW/cm 2; the high temper-
atures were used with high fluxes of incident energy 
to simulate conditions of operation when solar panels 
are within 0.4 AU of the sun. The short-circuit current, 
open-circuit voltage, and maximum power point were
extracted and reduced with the aid of a computer 
programmed to average the data for each cell assem-
bly type. In addition, the standard deviations and 95% 
confidence limits were determined. For each cell type, 
plots are given in the report to show the dependence 
of cell efficiency on temperature and intensity of il-
lumination and a curve shape factor which expresses 
the "squareness" of the current-voltage (I-V) curve as 
a function of temperature and intensity. 
The functions of p (T) and c (S), which represent 
the dependence of cell efficiency on temperature T 
and intensity S, respectively, were determined by 
minimizing, in a weighted least squares sense, the 
difference between the maximum power measure-
ments and the power defined by the function: 
P(S,T) =P(1 sun, 60°C) 0 (T)j(S)S. 
This procedure results in uncoupling the effects of 
temperature and intensity on maximum power and 
allows them to be examined separately. Thus, char-
acteristics such as a decrease in cell efficiency at high 
solar intensity due to a high series resistance are 
clearly displayed. 
The curve shape factor which depicts the "square-
ness" of the IN curve is defined as the ratio of max-
imum power to the product of short-circuit current 
and open-circuit voltage. Ideally, with a rectangular 
IN curve, the curve shape factor will be one. Thus, 
the extent to which the curve shape factor is less than 
one indicates the degree of rounding of the knee of 
the IN curve. 
The thermal radiation properties of solar cell-cover-
glass combinations and solar cell modules were also 
measured to obtain data useful for correlation of ob-
served performance and as design data for thermal 
(continued overleaf) 
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.
C]
https://ntrs.nasa.gov/search.jsp?R=19720000186 2020-03-17T03:32:48+00:00Z
control of spacecraft solar panels. The effects of 
ultraviolet and particulate irradiation (predominantly 
protons with a mixture of alpha particles) were also 
determined in 500- and 2400-hour tests. The results 
of a brief study of adhesives for solar cell fabrication 
are included in the report. 
Note: 
The following documentation may be obtained 
from:
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95)
Reference: 
JPL Technical Memorandum 33-473 (N71-
23780), Measured Performance of Silicon 
Solar Cell Assemblies Designed for Use at 
High Solar Intensities. 	 — 
Source: Ronald C. Ross, Jr., Robert K. Yasui, 
Wiktor Jaworski, Liang-Chi Wen, and 
Edward L. Cleland of	 — 
Caltech/JPL 
under contract to 
NASA Pasadena Office 
(NPO-11847)
. 
. 
B72-10186	 Category 01


Performance of silicon solar cell assemblies

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