Silicon-based solar cells Characteristics and production processes ...

Silicon-based solar cells – characteristics and production processes
Fig. 4. Provided by the producer, original pack of 125 items of six-inch mono-crystalline
silicon wafers Cz-Si (a) and poly-crystalline silicon plates mc-Si (b), 200 µm thick, used in the
solar cell production. Fragment of a silicon Cz-Si roller made with the Czochralski process (c)
and the cut-out plate used in the IC (Integrated Circuit) sector (d), next to a four-inch single
mc-Si silicon plate, after the elimination of the defected layer, resulting from the block
sawing (e).
Tab. 4. Value of the global production of crystalline silicon for electronics (sector IC) and
photovoltaics (sector PV) up to 2008, and the forecast value for the years 2009 and 2010, as
well as the average mass value of a crystalline silicon plate, used in the production of 1 Watt
of a solar cell capacity – SSC [10].
Year Si Production [tonne/year] SSC
Cell production
Sector IC Sector PV
[g/W p ]
[MW p ]
2004 18500 14300 13 1100
2005 19500 16300 11 1800
2006 20400 18850 10 2400
2007 21400 29300 9.0 4100
2008 22500 67500 8.5 6900
2009 23600 86250 8.0 9300
2010 24700 97800 7.5 13000
The development of the PV sector is connected with the significant growth of the
crystalline silicon production and the systematic drop of the SI cells’ thickness, which
at the beginning of the decade equaled 300 µm, and now has been reduced to 200
µm, although there are already producers who offer 175 µm thick cells. A further
thickness reduction, down to the level of 100 ÷ 120 µm, is also possible with the use
of new construction concepts for the cells with the back contact points made by
means of a laser radiation beam, type LFC (Laser Fired Contact), the cells with MWT
(Metallization Wrap Through) or the cells with IBC (Interdigitated Back Contact).
In order to obtain a crystalline silicon plate, ready for the cell production, it is
necessary to apply numerous processes, whose implementation is basically possible
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