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

Silicon-based solar cells – characteristics and production processes
electrode on the front side and a positive one on the back side. The cells are
connected with thin copper strips, 2 mm wide and 0.15 mm thick, coated with the
Sn62%Pb36%Ag2% tin alloy.
Fig. 37. Techniques of connecting solar cells; the initial values of the current intensity at the
point of maximum power (I m ) and of the voltage at the point of maximum power (V m ) for a
series and parallel sequence of several single mc-Si cells with the surface area of 100 cm 2 .
As single solar cells are electron devices of a very fragile construction, the cells
connected in series or in parallel are hermetized in the process of lamination into
photovoltaic modules. Only the module is an element which can be applied as
a practical and useful source of direct current, under all kinds of atmospheric and
terrain conditions. Most of the industrial mc-Si and Cz-Si modules are manufactured
out of 36 or 72 solar cells connected in series, in such a way so that the module’s
voltage V m is higher than the rated voltage required to charge a typical 12 or 24 volt
accumulator. The cells for the given module are selected according to the value of I m ,
yet one should also take into account the value of R sh [73]. The construction of
a typical PV module is a sequence of component layers, which is presented in Fig. 38.
Fig. 38. Construction layers of a crystalline silicon-based photovoltaic module.
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