knjiga solarna energija dobra

THE HISTORY OF SPACE SOLAR CELLS 415
cells providing over 10 kW of power. The 1970s also saw the first use of shallow junction
silicon cells for increased blue response and current output, the use of the back surface
field, the low–high junction theory for increased silicon cell voltage output, and the
development of wraparound contacts for high efficiency silicon (HES) cells to enable
automated array assembly and to reduce costs.
In the 1980s, the gap between theoretical efficiencies and experimental efficiencies
for silicon, gallium arsenide, and indium phosphide became almost nonexistent (see
Figure 10.1) [12]. New thin-film cells of amorphous silicon and CuInGaSe 2 brought the
possibility of higher thin-film efficiencies and flexible, lightweight substrates that excited
the space community. However, silicon still provided the majority of the power for space
and eventually the solar arrays for the International Space Station (ISS) (see Figure 10.2).
35
30
25
20
15
10
Ge
Si
CIGS
CIS
InP
Best confirmed efficiency under AM1.5
standard conditions (T = 25°C)
GaAs
Cu 2 S CuInS 2
CdTe
a-Si:H
CuGaSe 2
Black-body limit
AM0
AM1.5
CdS
5
0.5 1.0 1.5 2.0 2.5
Band gap
[eV]
Figure 10.1 Comparison of measured cell efficiencies to the theoretical limits as a function of
band gap [12]
(a)
(b)
Figure 10.2 (a) Current status of International Space Station (ISS) and (b) planned configuration
of ISS by 2004. (Pictures courtesy of NASA)