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When certain materials called semi-conductors are exposed to sunlight, the photons can convey their energy to the semi-conductor's valence electrons, freeing the latter from the bond that ties them to their respective atoms.
The physical structure of semi-conductors creates an electric field that establishes a path for the released electrons, thereby generating an electric current. Once the current is generated, operation is the same as in conventional electricity generation: the direct current produced is conveyed to the inverters where it is converted into alternating current; from there it passes through a transformer that raises the voltage to the level required for coupling to the 15-kilovolt grid to which the plant is connected.
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The
electrons released - one per broken bond - circulate within the solid.
The space left by each freed electron, called a vacancies, also "move"
from one atom to the next within the solid as a result of the movement
of the respective electrons. Vacancies behave in many respects like
particles with a positive charge of the same absolute value as the electron's
negative charge.