Photovoltaic System - Viessmann Vitovolt 200 Technical Manual

1.3 Photovoltaic system

Solar cell Solar panel
A
A Solar cell
Sectional view of a solar cell
A
VITOVOLT
Solar generator
B
B Solar panel
A Negative electrode
B Boundary layer
C n doped silicone
D p doped silicone
E Positive electrode
B
C
D
E
C
C Solar generator
1.3 Photovoltaic system
The solar cell is the smallest component
of a photovoltaic system. A great number
of solar cells are linked to form a single
panel. A common photovoltaic system
comprises several solar panels, the
so−called solar generator.
The highly pure silicone is deliberately
contaminated with boron (p−doped) at the
point of manufacture. Phosphorous
atoms are inserted on the side facing the
sun (n−doped). In the boundary layer (p−n
junction) an electrical field is created that
has its negative pole p−doped and its
positive pole n−doped. After this
separation, electrons will be taken off the
silicone atoms in an n−doped direction.
The resulting fault (hole) migrates in a
reverse direction.
The p−n junction provides the electrical
activity through an electron surplus on
the side facing the sun and an electron
shortage at the back.
If a consumer is connected to these poles,
a current flows. The electrons released by
the photons migrate from the negative to
the positive pole, i.e. there is a current
from the positive to the negative pole.
Contrary to mechanical power
generation, e.g. by a bicycle dynamo,
there are no mechanical moving parts in a
solar cell, which theoretically provides an
unlimited service life.
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