Product = Solar Cell |
Remarks |
"Bulk" Solar
Cells |
General definition |
The light absorbing part is relatively thick (> 100 µm); no
substrate for mechanical stability is needed. Nearly all solar cells on roof
tops now (= 2007) fall into this category; and they are practically
always made from Si. |
Single crystalline Si |
Best Mass product in terms of solar cell efficiency (about 21 % by
now) |
"Multi"crystalline Si |
Slightly worse and somewhat cheaper than single crystalline Si, but
market leader |
GaAs solar cell |
Very good . And very expensive. Some space applications |
|
Thin film Solar Cells |
General definition |
Typically (0.5 - 30) µm film on substrate. |
Amorphous Si |
The classic thin film cell; found in most small-scale applications
(watches, pocket calculators, ...). Major performance problems even after >
20 a R&D |
Nanocrsytalline Si |
The solar cell of the future? Not yet in production |
CuInxGa1-xSeyS1-y |
So-called "CIGS" solar cells. Mass
production has started. |
CdTe |
Some production; future unclear |
Organic semiconductors |
Max. efficiency at present (2007) around 5 %. We shall
see. |
|
Specialities |
TiO2 plus .... |
The so-called "Grätzel Cell". Sintered
TiO2 nanoparticles coated with organic molecules absorb the
light; carrier transport occurs via the TiO2 and a Redox
electrolyte |
Tandem cells |
Several thin layers of semiconductor with different band gaps on top of
each other. Very high efficiency and price. |
Concentrator cells |
"Small" high-efficiency cell mounted in the focus of a parabolic
mirror. Saves on (expensive) semiconductor on the expense of mirror and
positioning device, Only usable in countries with lots of direct sun light (not
in S.-H.). Gets hot! |