Fronius IG 300 - Manual (Page 14)

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The amount of solar energy radiated worldwide amounts to approx.
1,540,000,000,000,000,000 kWh per year (1,540 peta kWh / year). This is 15,000 times
more than the total electricity consumed. We would like to congratulate you on your
decision to make active use of the world’s largest energy pool. Incidentally, the photovol-
taic effect was originally discovered in 1839 by the French physicist Alexandre-Edmond
Bequerel. The term ‘photovoltaic’ comes from the driving force behind this technology,
the light beam. The light beam consists of unimaginably small particles called photons. General
How a photovoltaic system works
For simplicity, our starting point will be an explanation of a pure silicon solar cell. If we
think back to our physics lessons at school we might recall that in its outer electron
sheath, silicon has four electrons around its atomic nucleus. These four electrons are
known as the ‘valency electrons’. The photons, i.e. the sunlight, penetrate the solar cells
and strengthen the valency electrons by adding energy. The electron finally detaches
itself from the silicon atom, leaving behind a positively-charged atom.
To ensure that the detached electrons all flow in the same direction to form a current, the
front and rear sides of the cell must have opposite polarities.
The silicon atoms on the front side are displaced by a small number of phosphorus
atoms with their extra valency electron. On the rear side of the cell, on the other hand, in
addition to the silicon atoms, boron atoms (which have only three valency electrons) are
also built up.
The resulting imbalance between the positive and negative poles causes the electrons to
flow, thus producing an electrical current.
When a number of these solar cells are packed together behind a pane of glass, they
form one of your solar modules.
Current is gene-
rated on the roof